Quantum Efficiency[edit | edit source]

Wikipedia http://en.wikipedia.org/wiki/Quantum_efficiency

Has an interesting interaction graph which allows you to change the emitter and base collection properties to change the Jsc quantum efficiency. http://web.archive.org/web/20160911021123/http://pvcdrom.pveducation.org/CELLOPER/QUANTUM.HTM

The following 65 Papers were found using the link below.


Electroluminescence in amorphous silicon 1976[edit | edit source]

Abstract:Electroluminescence has been obtained in forward-biased p-i-n diodes, and also in Schottky barrier diodes fabricated from discharge-produced amorphous Si. The emission at 78 °K in both electroluminescence and photoluminescence peaks at 1.28±0.08 eV in a 0.2-eV broad band with an external quantum efficiency of ~10−3.

Pankove, J.I. (RCA Labs., Princeton, NJ, USA); Carlson, D.E. Source: Applied Physics Letters, v 29, n 9, p 620-22, 1 Nov. 1976 http://scitation.aip.org.proxy.queensu.ca/getabs/servlet/GetabsServlet?prog=normal&id=APPLAB000029000009000620000001&idtype=cvips&gifs=yes

10_01_22_Electroluminescence in amorphous silicon

Photoluminescence in sputtered amorphous silicon-hydrogen alloys 1980[edit | edit source]

Deep hole traps in high efficiency Schottky barrier solar cells on sputtered amorphous silicon as evidenced by spectral response and thermally stimulated current measurements

Field-dependent quantum efficiency in hydrogenated amorphous silicon 1980[edit | edit source]

Abstract:A model calculation of the electric field dependence of the quantum efficiency for electron-hole pair production in hydrogenated amorphous silicon is presented and compared with recent measurements of the electric field dependence of the solar-cell collection efficiency. The theory, based on electric field reduction of geminate recombination of the excited electron-hole pair, agrees well with experiment.

Crandall, R. (RCA Labs., Princeton, NJ, USA) Source: Applied Physics Letters, v 36, n 7, p 607-8, 1 April 1980 Database: Inspec http://scitation.aip.org.proxy.queensu.ca/getabs/servlet/GetabsServlet?prog=normal&id=APPLAB000036000007000607000001&idtype=cvips&gifs=yes

10_01_22_Field-dependent quantum efficiency in hydrogenated amorphous silicon

Development of amorphous silicon stacked cells 1980[edit | edit source]

Hanak, J.J. (RCA Labs., Princeton, NJ, USA); Faughnan, B.; Korsun, V.; Pellicane, J.P. Source: Fourteenth IEEE Photovoltaic Specialists Conference 1980, p 1209-13, 1980

On the computation of Onsager quantum efficiency 1981[edit | edit source]

Abstract:A new method of computing the Onsager quantum efficiency of photogeneration is presented. This method is shown to be much faster than and as accurate as the series method used previously. Results applicable to a-Si (dielectric constant=11.5) are given as an example.

Kwok-leung Yip (Joseph C. Wilson Center for Technol., Xerox Corp., Webster, NY, USA); Li, L.S.; Chen, I. Source: Journal of Chemical Physics, v 74, n 1, p 751-3, 1 Jan. 1981 http://scitation.aip.org.proxy.queensu.ca/getabs/servlet/GetabsServlet?prog=normal&id=JCPSA6000074000001000751000001&idtype=cvips&gifs=yes 10_01_22_On the computation of Onsager quantum efficiency

Computer model of amorphous silicon solar cell 1982[edit | edit source]

Abstract:A computer model to simulate a n+ip+ amorphous silicon solar cell was developed. This model is based on the computer simulations of solar cells by T. Chappell and the Read diode by Scharfetter and Gummel. The model is used to generate field plots, band diagrams, quantum efficiency curves, I-V characteristics, carrier density distribution plots, carrier generation, and carrier recombination plots. The simulated values of short circuit current density, open circuit voltage, fill factor, efficiency, junction quality factor, quantum efficiency, junction quality factor, quantum efficiency, slope of I-V curves at V = 0 and V = Voc are in good agreement with the measured cell values. Computer simulation shows that a major loss mechanism is the back diffusion of holes into the n+ layer which is diminished by a strong electric field provided by a high concentration of ionized donors in the n+ layer. Projection of cell performance based on the production of n+ and p+ contact layers with ionized donor and ionized acceptor concentrations in the 2×1020 cm−3 range indicates cell efficiencies greater than 10%.

Swartz, G.A. (RCA Labs., Princeton, NJ, USA) Source: Journal of Applied Physics, v 53, n 1, p 712-19, Jan. 1982 http://scitation.aip.org.proxy.queensu.ca/getabs/servlet/GetabsServlet?prog=normal&id=JAPIAU000053000001000712000001&idtype=cvips&gifs=yes 10_01_22_Computer model of amorphous silicon solar cell

Observation of electroluminescence from amorphous silicon solar cells at room temperature 1982[edit | edit source]

Abstract:Electroluminescence from a-Si pin, pi(B-doped)n, and nip solar cells was observed at room temperature (300 K) for the first time. The electroluminescence spectrum of the nip cell showed very broad with a peak at 1.31 eV or slightly less. The external quantum efficiency of the nip cell was 10-5% at 300 K. Electroluminescence intensity from this cell was stronger than that from the pin cell. It became clear that this can be attributed to the difference in the current transport mechanism of the nip and pin cells. A pin cell whose i-layer was slightly boron doped, the pi(B)n cell, gave a stronger electroluminescence intensity than a usual pin cell.

Lim, K.S. (Tokyo Inst. of Technol., Tokyo, Japan); Konagai, M.; Takahashi, K. Source: Japanese Journal of Applied Physics, Part 2 (Letters), v 21, n 8, p L473-5, Aug. 1982 http://jjap.ipap.jp.proxy.queensu.ca/link?JJAP/21/L473/

10_01_22_Observation of Electroluminescence from Amorphous Silicon Solar Cells at Room Temperature

The absolute luminescence quantum efficiency in hydrogenated amorphous silicon 1983[edit | edit source]

Jackson, W.B. (Xerox Palo Alto Res. Center, Palo Alto, CA, USA); Nemanich, R.J. Source: Journal of Non-Crystalline Solids, v 59-60, pt.1, p 353-6, Dec. 1983 Database: Inspec

Photovoltaically active p layers of amorphous silicon 1983[edit | edit source]

Abstract:Studies on amorphous silicon p-n diodes have shown that the p layers are photovoltaically active. Jsc of up to 3.4 mA/cm2 and Voc of 780 mV have been observed. Detailed quantum efficiency measurements were performed as a function of bias voltage, p-layer thickness, and boron doping. The data fit a simple depletion width model in which all photogenerated carriers created inside the depletion region are collected. An additional ``reverse barrier depletion width is assumed at the interface between the front transparent oxide electrode and the p layer to explain the results. A 10-nm-thick p layer typically used in p-i-n cells could collect up to 1 mA/cm2 if the electric field in the p layer is greater than 105 V/cm.

Faughnan, B.W. (RCA Labs., Princeton, NJ, USA); Hanak, J.J. Source: Journal of Non-Crystalline Solids, v 59-60, pt.2, p 1127-30, Dec. 1983 http://scitation.aip.org.proxy.queensu.ca/getpdf/servlet/GetPDFServlet?filetype=pdf&id=APPLAB000042000008000722000001&idtype=cvips&prog=normal 10_01_22_Photovoltaically active p layers of amorphous silicon

High quantum efficiency a-Si:H picosecond transit-time limited Schottky barrier photodetectors 1984[edit | edit source]

Abstract:Amorphous silicon films have previously been utilized to make high speed photoconductive detectors with response times ranging from 4–200 psec in microstrip transmission line structures. However, in typical devices, the low carrier mobilities resulted in poor carrier collection efficiencies resulting in quantum efficiencies in the range 0.001–0.3%. We have demonstrated photogenerated carrier sweep-out in Schottky barrier photodetectors with internal quantum efficiencies of 36% (0.18 A/W) and sampling oscilloscope limited response times of 40 psec (FWHM) using 100 nm-thick films of rf-glow discharge deposited a-Si:H in a new transmission line structure. The estimated deconvolved response time was 27 psec. These a-Si:H detectors are compared in speed and sensitivity to high mobility crystalline detectors.

Johnson, A.M. (AT&T Bell Labs., Holmdel, NJ, USA); Glass, A.M.; Olson, D.H.; Simpson, W.M.; Harbison, J.P. Source: Journal of Non-Crystalline Solids, v 66, n 1-2, p 381-6, July 1984 http://www.sciencedirect.com.proxy.queensu.ca/science?_ob=ArticleURL&_udi=B6TXM-48CXV8T-39G&_user=1025668&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050549&_version=1&_urlVersion=0&_userid=1025668&md5=a88acc135efb81d2bd2e56431adda4d3 10_01_22_High quantum efficiency a-SiH picosecond transit-time limited Schottky barrier photodetectors

High quantum efficiency amorphous silicon photodetectors with picosecond response times 1984[edit | edit source]

Abstract:Amorphous silicon Schottky barrier photodetectors with internal quantum efficiencies of 36% and sampling oscilloscope limited response times of 40 ps (full width at half-maximum) have been fabricated. Utilizing ultrathin films of rf glow discharge deposited hydrogenated amorphous silicon, carrier sweep-out was achieved in a new microstrip transmission line structure. The performance of these devices, for picosecond pulse detection, is now comparable to that of crystalline semiconductor detectors

Johnson, A.M. (Bell Labs., Holmdel, NJ, USA); Glass, A.M.; Olson, D.H.; Simpson, W.M.; Harbison, J.P. Source: Applied Physics Letters, v 44, n 4, p 450-2, 15 Feb. 1984 http://scitation.aip.org.proxy.queensu.ca/getabs/servlet/GetabsServlet?prog=normal&id=APPLAB000044000004000450000001&idtype=cvips&gifs=yes 10_01_22_High quantum efficiency amorphous silicon photodetectors with picosecond response times

Experimental observation of light trapping in hydrogenated amorphous silicon solar cells 1985[edit | edit source]

Abstract:Experimental evidence for light trapping in glass/conductive transparent oxide/p-i-n/metal hydrogenated amorphous silicon solar cell structures is presented. A short-circuit current of 17.8 mA/cm2 has previously been reported for a cell made with this structure. The light trapping is treated by a modification of the Yablonovitch–Cody (YC) statistical theory of light trapping in textured layers [E. Yablonovitch and G. D. Cody, IEEE Trans. Electron. Devices ED-29, 300 (1982)]. Reflection measurements show that 80% of the incident light is trapped. Quantum efficiency measurements made on cells with back electrode metals of different reflectivity are shown to be in agreement with the predictions of the YC theory.

Faughnan, B.W. (RCA Labs., Princeton, NJ, USA) Source: Journal of Applied Physics, v 58, n 7, p 2746-50, 1 Oct. 1985 http://scitation.aip.org.proxy.queensu.ca/getpdf/servlet/GetPDFServlet?filetype=pdf&id=JAPIAU000058000007002746000001&idtype=cvips&prog=normal 10_01_22_Experimental observation of light trapping in hydrogenated amorphous silicon solar cells

Optical properties and quantum efficiency of a-Si1-xCx:H/a-Si:H solar cells 1985[edit | edit source]

Abstract:The optical properties of all components of heterojunction solar cells based on hydrogenated amorphous silicon (a‐Si:H) have been measured individually. By combining these data with knowledge of the cell geometry, an envelope quantum efficiency curve is generated, being simply the fraction of incident photons absorbed in the i layer of the p‐i‐n cell. Resultant curves for typical cell dimensions are seen to agree remarkably well with observed values for cells with long minority‐carrier collection lengths. The model is then used as a diagnostic tool, and finally is demonstrated to have predictive value in the quest for further optimization of solar‐cell performance.

Schade, H. (RCA Labs., Princeton, NJ, USA); Smith, Z.E. Source: Journal of Applied Physics, v 57, n 2, p 568-74, 15 Jan. 1985 http://ieeexplore.ieee.org.proxy.queensu.ca/Xplore/defdeny.jsp?url=http://ieeexplore.ieee.org/stamp/stamp.jsp%3Ftp%3D%26arnumber%3D5115155&denyReason=-133&arnumber=5115155&productsMatched=null 10_01_22_Optical properties and quantum efficiency of a-Si1−xCxH a-SiH solar cells

Determination of the mobility gap in amorphous silicon from a low temperature photoconductivity measurement 1985[edit | edit source]

Abstract:Measurement of the spectral dependence of photoconductivity and quantum efficiency at liquid helium temperature is presented. The mobility gap value was found to be quite close to the Tauc optical gap value for undoped good quality material.

Vanecek, M. (Inst. of Phys., Czechoslovak Acad. of Sci., Prague, Czechoslovakia); Stuchlik, J.; Kocka, J.; Triska, A. Source: Journal of Non-Crystalline Solids, v 77-78, pt.1, p 299-302, 11 Dec. 1985 http://www.sciencedirect.com.proxy.queensu.ca/science?_ob=ArticleURL&_udi=B6TXM-48N5J8B-G9&_user=1025668&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050549&_version=1&_urlVersion=0&_userid=1025668&md5=35adac45ad89416aa83987dba3f13cb7 10_01_22_Determination of the mobility gap in amorphous silicon from a low temperature photoconductivity measurement

Optical properties of hydrogenated amorphous silicon based solar cells 1986[edit | edit source]

Ellis, F.B., Jr. (Chronar Corp., Lawrenceville, NJ, USA); Delahoy, A.E. Source: Solar Energy Materials, v 13, n 2, p 109-32, Feb.-March 1986

Status of fluorinated amorphous silicon-germanium alloys and multijunction devices 1987[edit | edit source]

Ross, R. (Energy Conversion Devices Inc., Troy, MI, USA); Mohr, R.; Fournier, J.; Yang, J. Source: Conference Record of the Nineteenth IEEE Photovoltaic Specialists Conference - 1987 (Cat. No.87CH2400-0), p 327-30, 1987 Database: Inspec

High efficiency multi-junction solar cells using amorphous silicon and amorphous silicon-germanium alloys 1988[edit | edit source]

Abstract: We have incorporated a new c e l l design and achieved a 13.7% conversion efficiency using amorphous s i l i c o n and amorphous silicon-germanium alloys i n a three-cell stacked-junction configuration. This i s the highest efficiency reported t o date f o r t h i n - f i l m solar cells. The efficiency value was measured using a t r i p l e - source solar simulator adjusted f o r global AM1.5 test conditions. This t r i p l e device has a structure of stainless steel/textured s i l v e r / zinc oxide/ni lp/ni p/ni 3p/ITO/grid. We have used an amorphous s?licon-germanium alloy with the new design i n the il layer, and amorphous s i l i c o n alloys i n the i2 and i layers The 3-V characteristic shows Jsc = 7?66 mA/cm*, VOC

2.55 Volts, FF[edit | edit source]

0.70, with an active area of
  1. 25 cm2. The quantum efficiency measurement of

t h i s device shows 60% c o l l e c t i o n a t 400 nm, 93% at the peak, 55% at 800 nm, and 21% at 850 nm. The t o t a l photocurrent density obtained by integrating the quantum efficiency enyelope with the global AM1.5 spectrum i s 23.5 mA/cm.


Yang, J. (Energy Conversion Devices Inc., Troy, MI, USA); Ross, R.; Glatfelter, T.; Mohr, R.; Hammond, G.; Bernotaitis, C.; Chen, E.; Burdick, J.; Hopson, M.; Guha, S. Source: Conference Record of the Twentieth IEEE Photovoltaic Specialists Conference - 1988 (Cat. No.88CH2527-0), p 241-6 vol.1, 1988


Performance of silicon solar cells under hot and dusty environmental conditions 1988[edit | edit source]

Bajpai, S.C. (Sokoto Energy Res. Centre, Sokoto Univ., Nigeria); Gupta, R.C. Source: Indian Journal of Pure and Applied Physics, v 26, n 5, p 364-9, May 1988

On mobility-lifetime problem and on quantum efficiency of photogeneration in amorphous silicon 1989[edit | edit source]

Abstract:Discrepancy in the value of mobility-lifetime (μ τ) product measured under different experimental conditions is elucidated with the help of steady-state and transient demarcation level concept. Experimental data on the quantum efficiency of photogeneration of free carriers presented as a function of electric field (5×103−2×105V/cm) and temperature (300-14K). For sufficiently high electric fields, η approaches unity even at very low temperature.


Vanecek, M. (Inst. of Phys., Czechoslovak Acad. of Sci., Praha, Czechoslovakia); Kocka, J.; Sipek, E.; Triska, A. Source: Journal of Non-Crystalline Solids, v 114, pt.2, p 447-9, 1989 Database: Inspec

10_01_25_On mobility - lifetime problem and on quantum efficiency of photogeneration in amorphous silicon

The effect of water vapor and oxygen in the processing environment on the properties of sputtered a-Si:H films 1989[edit | edit source]

Abstract: We show that the addition of small amounts of water vapor, or O2 into the processing ambient leads to significant improvements in the properties of a-Si:H films deposited by reactive magnetron sputtering at substrate temperatures <150°C. The relative fraction of polyhydride bonding, and defect densities are both reduced; the films show increased stability against light-soaking induced defects; while levels of oxygen in the films remain below 5×1018/cm3.


Cheng Wang (Dept. of Phys., North Carolina State Univ., Raleigh, NC, USA); Parsons, G.N.; Lucovsky, G. Source: Amorphous Silicon Technology-1989 Symposium, p 75-80, 1989

10_01_25_Effects of gas additives on the properties of a-SiH films

Effect of light soaking on the short-wavelength photoresponse in hydrogenated amorphous silicon 1990[edit | edit source]

Abstract:The spectrum of the values of µ, the product of quantum efficiency, lifetime, and mobility of photogenerated carriers, has been obtained in the wavelength range 300–900 nm, before and after light soaking. It has been shown that in the annealed state, these values are nearly independent of wavelength as well as film thickness. The values of µhave been found to decrease more drastically in the short-wavelength region after light soaking, similarly to that observed after moisture adsorption. Changes in band bending are not likely to be the cause of the decrease in response as the dark conductivity does not change on light soaking. The implications of the result are discussed.


Ghosh, S. (Energy Res. Unit, Indian Assoc. for the Cultivation of Sci., Calcutta, India); Ganguly, G. Source: Journal of Applied Physics, v 68, n 11, p 5896-8, 1 Dec. 1990

10_01_25_Effect of light soaking on the short-wavelength photoresponse in hydrogenated amorphous silicon

Effect of light induced defects on the quantum efficiency of amorphous silicon Schottky barrier solar cell structures 1991[edit | edit source]

Abstract: Changes in internal quantum efficiency (QE) of n-i- Pt Schottky barrier solar cells are directly correlated with light induced defects in the bulk a-Si:H. These short circuit QE's measured on cells 0.84 to 3.4pm thick in the annealed state and after open circuit degradation up to 650 hours with 100 mW/cm2 ENH white light were analyzed using a detailed numerical model to obtain the corresponding densities of mid-gap states and capture cross sections. The self consistent results obtained for the different thickness cell structures correlate light-induced, metastable defect creation with the degradation of the short circuit currents.


Malone, C.T. (Center for Electron. Mater. & Process., Pennsylvania State Univ., University Park, PA, USA); Nicque, J.L.; Fonash, S.J.; Wronski, C.R.; Bennett, M. Source: Conference Record of the Twenty Second IEEE Photovoltaic Specialists Conference - 1991 (Cat. No.91CH2953-8), p 1219-24 vol.2, 1991 Database: Inspec

10_01_25_Effect of light induced defects on the quantum efficiency of amorphous silicon Schottky barrier solar cell structures

Hydrogen content and the goal of stable efficient amorphous-silicon-based solar cells 1991[edit | edit source]

Fortmann, C.M. (Inst. of Energy Conversion, Delaware Univ., Newark, DE, USA); Hegedus, S.S.; Zhou, T.X.; Baron, B.N. Source: Solar Cells, v 30, n 1-4, p 255-60, May 1991

An experimental observation of photo-induced carrier multiplication in hydrogenated amorphous silicon 1991[edit | edit source]

Abstract:A photo-induced carrier multiplication in a hydrogenated amorphous silicon has been observed. A careful measurement of photo-carrier generation has been done with amorphous silicon Schottky barrier structure junctions as a function of incident photon energy in the range between 1.55eV and 6.2eV. The quantum efficiency is estimated to be multiplied by a factor of two in higher photon energy region than 5.4eV. This multiplication can be explained by an interband carrier ionization due to the energy given by a high energy photo-carrier.


Sugawa, S. (Canon Inc., Semicond. Dev. Center, Kanagawa, Japan); Ohmi, K.; Yamanobe, M.; Osada, Y. Source: Solid State Communications, v 80, n 6, p 373-6, Nov. 1991

10_01_25_ experimental observation of photo-induced carrier multiplication in hydrogenated amorphous silicon

Quantum efficiency of textured a-Si:H p-i-n solar cells after high intensity light-soaking 1992[edit | edit source]

Li, X.R. (Dept. of Electr. Eng., Princeton Univ., NJ, USA); Wagner, S.; Bennett, M.; Fonash, S.J. Source: Amorphous Silicon Technology - 1992, Symposium, p 929-33, 1992

Photocurrent multiplication in a hydrogenated amorphous silicon-based p-i-n junction with an a-SiN:H layer 1992[edit | edit source]

Abstract:Photocurrent multiplication has been observed in a hydrogenated amorphous silicon-based p-i/a-SiN:H/i-n structure junction under a reverse biased condition. A systematic investigation on the photocurrent characteristics in this junction system has been carried out. It has been shown from the analysis of the results that multiplication arises from the interband tunneling injection of valence band ``electron through the a-SiN:H barrier layer. A device modeling on the basis of the experimental data permits us to design the device structure for achieving better performances. As a preliminary optimization of device structure, an external quantum efficiency exceeding 70 has been obtained under the operation voltage 30 V in the heterojunction photodiode having an a-SiN:H (thickness of 40 nm with optical energy gap 2.1 eV) at the p a-SiC:H/i a-Si:H interface. The proposed highly sensitive photomultiplier device might have a wide variety of application fields such as a solid-state imager for high-definition televisions, etc.

Yoshimi, M. (Fac. of Eng. Sci., Osaka Univ., Toyonaka, Japan); Ishiko, T.; Hattori, K.; Okamoto, H.; Hamakawa, Y. Source: Journal of Applied Physics, v 72, n 7, p 3186-93, 1 Oct. 1992

10_01_25_Photocurrent multiplication in a hydrogenated amorphous silicon-based p-i-n junction with an a-SiNH layer

Mobility, recombination kinetics, and solar cell performance 1993[edit | edit source]

Abstract:In order to optimize the amorphous silicon structure for improved stabilized performance it is necessary to understand a great number of material parameters as they exist in the solar cell under operating conditions. Towards the goal of using the solar cells themselves for quantitative defect analysis we show that the short wavelength quantum efficiency measurement is a means to determine the total density of charged and uncharged dangling bonds in the i-layer as a function of light soaking time. The compound effect that dangling bond defects have on solar cell performance, consisting of the redistribution of the electric fields and decreased lifetimes are considered. The magnitude of the short wavelength response can be directly linked to the number of bulk defects in the solar cells. Also it is not possible to directly determine the electron mobility from solar cell characterization due to the diffusive carrier transport found in amorphous materials. Surprisingly, we do expect the electron mobility to be directly linked to the stability of the solar cells.


Fortmann, C.M. (Inst. de Microtechnol., Neuchatel Univ., Switzerland); Fischer, D. Source: Conference Record of the Twenty Third IEEE Photovoltaic Specialists Conference - 1993 (Cat. No.93CH3283-9), p 966-70, 1993


Measurement of the quantum efficiency of CsI, amorphous silicon and organometallic reflective photocathodes 1994[edit | edit source]

Measurement of the quantum efficiency of CsI, amorphous silicon and organometallic reflective photocathodes Malamud, G. (Lab de Phys. Nucl. et des Hautes Energies, Ecole Polytech., Palaiseau, France); Mine, Ph.; Vartsky, D.; Equer, B.; Besson, P.; Bourgeois, P.; Breskin, A.; Chechik, R. Source: Nuclear Instruments & Methods in Physics Research, Section A (Accelerators, Spectrometers, Detectors and Associated Equipment), v 348, n 2-3, p 275-9, 1 Sept. 1994 Database: Inspec

Fabrication of more stable materials and devices in amorphous silicon 1994[edit | edit source]

Abstract:We discuss two approaches for improving the stability of a-Si:H devices. The first approach relies on improving the stability of the material by controlling the growth chemistry. We show that when the film is subjected to a strong H atom flux during growth, its microstructure becomes very robust, with few polysilane-type chains and its stability is significantly improved. The stability is further enhanced by sub-ppm doping by diborane during growth. We speculate that diborane compensates the native oxygen donors, and changes the localized bonding environment, thereby improving stability. We have been able to obtain a very low mid-gap defect density after prolonged illumination under 10× sun intensity using the combination of H etching and compensation. We have also made devices in these materials. The devices were made on standard textured tin oxide substrates and had simple Al back reflectors. We had to use high C buffer layers to block the diffusion of B from the p into the i layer at these temperatures. The best device efficiency to-date for a device made at 375 C is 7.8%. The quantum efficiency data on the devices indicate very good µ products for holes in our materials. Stability experiments on these devices are in progress.


Dalal, V.L. (Dept. of Electr. & Comput. Eng., Iowa State Univ., Ames, IA, USA); Baldwin, G.; Ping, E.X.; Leonard, M.; Bhan, M. Source: AIP Conference Proceedings, n 303, p 460-7, 1994

couldn't dl file

Significant improvements in stability of amorphous silicon solar cells by using ECR deposition 1996[edit | edit source]

Abstract: The fabrication and stability of p-i-n amorphous Si(a-Si:H) solar cells using low pressure electron-cyclotron-resonance (ECR) discharge are reported. The cells are fabricated at high temperatures (325 to 375°C) on tin oxide substrates using a Hydrogen-ECR discharge. Problems relating to diffusion of B from the p-layer at these temperatures are solved using unique diffusion barriers. High fill factors (68%) have been achieved in these cells using 350 nm thick i-layers in a p-i-n structure. Quantum efficiency (QE) measurements show that the i-layers in these cells have low defect densities and Urbach energies. The ECR cells and companion glow discharge cells with similar initial device parameters were subjected to 200 mW/cm2 of xenon illumination for 160 h. The tests show that the ECR cells degrade significantly less than comparable glow discharge cells. Detailed measurements of quantum efficiency before and after light soaking show that the improved stability of the ECR cells is due to the more stable i-layer in these cells.


Dalal, V.L. (Microelectron. Res. Center, Iowa State Univ., Ames, IA, USA); Kaushal, S.; Knox, R.; Han, K.; Martin, F. Source: Journal of Non-Crystalline Solids, v 198-200, pt.2, p 1101-4, May 1996

10_01_25_Significant improvements in stability of amorphous silicon solar cells by using ECR deposition

An amorphous silicon alloy triple-junction solar cell with 14.6% initial and 13.0% stable efficiencies 1997[edit | edit source]

Abstract:We have achieved 14.6% initial and 13.0% stable conversion efficiencies using an amorphous silicon-based alloy in a spectrum-splitting, triple-junction structure. These efficiencies have been confirmed independently by the National Renewable Energy Laboratory. Key factors leading to this major advance include improvements made in the low band-gap amorphous silicon–germanium alloy cell, the pn tunnel junction between the component cells, and the top conducting oxide.


Yang, J. (United Solar Syst. Corp., Troy, MI, USA); Banerjee, A.; Guha, S. Source: Amorphous and Microcrystalline Silicon Technology - 1997 Symposium, p 693-8, 1997

10_01_25_Triple-junction amorphous silicon alloy solar cell with 14.6% initial and 13.0% stable conversion efficiencies

A model for quantum efficiency and detectivity of n+p and n+n−p Hg1−xCdxTe photodiodes 1997[edit | edit source]

Abstract:In this paper a model for calculating the quantum efficiency � and the specific detectivity D� of both n+p and n+n−p photodiodes, considering both frontand backside illuminated configurations, is presented. The n+n−p diode is analysed by assuming a step model for the concentration profile. The effects of the surface recombination velocities at different surfaces/interfaces of the diode, the minority carrier lifetimes and the carrier concentrations are considered. It is pointed out that the parameter to be optimized for a photodiode is D� and not the zero-bias resistance–area product R0A, although the latter combines with the quantum efficiency to determine the behaviour of D�. Based on our calculations, it is observed that the values of different parameters that maximize R0A are different from those that are optimal for high quantum efficiency. For sufficiently high R0A, � dominates D�; otherwise, both factors affect D�. The calculation of D� done here refers to the long-wavelength IR region where often R0A is low, with the result that the injection efficiency into the CCD multiplexer is decreased, which has been taken into account.

This paper has equations to model the quantum efficiency. Might be useful but I believe that the equations deal with this specific semiconductor set-up.


V Dhar and R Ashokan Solid State Physics Laboratory, Lucknow Road, Delhi 110054, India Received 9 October 1996, accepted for publication 17 January 1997 Semicond. Sci. Technol. 12 (1997) 580–588. Printed in the UK PII: S0268-1242(97)78522-5

10_01_27_A model for quantum efficiency and detectivity of n+p and n+n−p Hg1−xCdxTe photodiodes

Widegap a-Si:H films prepared at low substrate temperature 1997[edit | edit source]

Abstract:Wide bandgap hydrogenated amorphous silicon (a-Si:H) films have been prepared by the PECVD method at a low substrate temperature (80°C) controlling the incorporation of hydrogen (bonded with silicon) into the film. Optimizing the deposition parameters viz. hydrogen dilution, rf power, a-Si:H film with Eg 1.90 eV and σph ≥ 10−4 Scm−1 has been developed. This film exhibited better optoelectronic properties compared to a-SiC:H of similar optical gap. The quantum efficiency measurement on the Schottky barrier solar cell structure showed a definite enhancement of blue response. Surface reaction as well as structural relaxation under suitable deposition condition have been claimed to be responsible for the development of such material.


Saha, S.C. (Energy Res. Unit, Indian Assoc. for the Cultivation of Sci., Calcutta, India); Ghosh, S.; Ray, S. Source: Solar Energy Materials and Solar Cells, v 45, n 2, p 115-26, 25 Jan. 1997

10_01_25_Widegap a-SiH films prepared at low substrate temperature

Interfaces in a-Si:H solar cell structures 1997[edit | edit source]

Abstract:The performance of amorphous silicon based solar cells depends on the tailored properties of the various layer materials making up the cell structure as well as on the properties and on the design of the interface regions between the layers. The electronic properties related to the various interfaces are markedly influenced by the Fermi level position within these regions, and by structural properties and chemical compositions resulting from the preparation conditions. Results are presented for the p/i and the TCO/p interfaces and discussed with respect to device performance. Further examples of interface effects are described which are related to chemical reactions and hydrogen diffusion in the course of sample preparation.


Stiebig, H. (Inst. fur Schicht- und Ionentech., Forschungszentrum Julich GmbH, Germany); Siebke, F.; Beyer, W.; Beneking, C.; Rech, B.; Wagner, H. Source: Solar Energy Materials and Solar Cells, v 48, n 1-4, p 351-63, Nov. 1997

10_01_25_Interfaces in a-SiH solar cell structures

Signal, noise, and detective quantum efficiency of a-Si:H flat-panel imagers 1998[edit | edit source]

Abstract:Flat-panel imagers based upon the technology of thin-film amorphous silicon transistors and photodiodes are under investigation for a wide variety of medical imaging applications. This thesis presents quantitative empirical and theoretical investigations of the imaging performance of such imaging systems. Performance was evaluated in terms of imager signal size, spatial resolution, noise characteristics, and signal-to-noise ratio for a wide variety of imaging system configurations and exposure conditions relevant to medical imaging. A theoretical model based upon cascaded systems analysis allowed prediction of imager signal, noise, and detective quantum efficiency (DQE), and theoretical results were found to agree well with empirical measurements. The empirical and theoretical analyses yielded quantification of the performance of existing imager designs, allowed investigation of the potential performance of future flat-panel imaging systems, and provided a methodology for identifying optimal imager configurations for various applications and imaging tasks. There is every indication that flat-panel imagers could provide performance superior to that of existing clinical imaging technologies. For example, in general x-ray radiography, mammography, and radiotherapy portal imaging, such systems could provide DQE exceeding 60%, 80%, and 1.5%, respectively, approximately twice that of film-based systems. However, for applications involving very low exposures per image, e.g., real-time fluoroscopy, flat-panel imagers may suffer from reduced signal-to-noise ratio. The analyses developed in this thesis provide a general description of imager signal and noise as well as a means of identifying strategies for improved imager performance


Siewerdsen, J.H. (Dept. of Radiat. Oncology, University of Michigan, Ann Arbor, MI, USA) Source: Medical Physics, v 25, n 11, p 2250, Nov. 1998

can't dl full article

Degradation and annealing of amorphous silicon solar cells by current injection experiment and modeling 1999[edit | edit source]

Abstract:In this paper we report in detail on the effect of current injection in amorphous silicon solar cells. A set of devices has been degraded and then annealed at different current intensities. Device performances during the whole experiment have been monitored by current–voltage characteristics and quantum efficiency curves. It has been found that annealing rate increases with current intensity, while stabilized photovoltaic parameters decrease. Time evolution of efficiency and short-circuit current during degradation has been reproduced by a numerical device modeling, resulting in a pronounced increase of defects near the p–i interface. The model also demonstrated that annealing results are not well reproduced if current-induced annealing is not energy selective.


Caputo, D. (Dept. of Electron. Eng., Tor Vergata Univ., Rome, Italy) Source: Solar Energy Materials and Solar Cells, v 59, n 3, p 289-98, Oct. 1999

10_01_25_Degradation and annealing of amorphous silicon solar cells by current injection experiment and modeling

Simulation of quantum efficiency spectroscopy for amorphous silicon p-i-n junctions 1999[edit | edit source]

Estwick, R. (Dept. of Electr. Eng. & Comput. Eng., Iowa State Univ., Ames, IA, USA); Dalal, V.L. Source: Amorphous and Heterogeneous Silicon Thin Films: Fundamentals to Devices - 1999. Symposium. (Materials Research Society Symposium Proceedings Vol.557), p 37-42, 1999 Database: Inspec

Thermally enhanced quantum efficiency in hydrogenated amorphous silicon p-i-n photodiodes studied by intensity-modulated photocurrent spectroscopy 1999[edit | edit source]

Abstract: is shown that at zero bias or slightly reverse bias the photocurrent quantum yield of hydrogenated amorphous Si (a-Si: H) p+-i-n+ photodiodes increases with decreasing absorbed photon flux. The quantum yield can exceed unity. The dynamics of photogenerated charge carriers in the intrinsic layer of a-Si: H were studied by intensity-modulated photocurrent spectroscopy (IMPS). A model is proposed, which accounts for the enhanced quantum yield at low light intensities. Basically, the increase in the quantum yield is explained by thermal generation of charge carriers mediated by a one-electron defect state formed under illumination. The model is supported by the results of IMPS measurements.


Vanmaekelbergh, D. (Debye Inst., Utrecht Univ., Netherlands); van de Lagemaat, J.; Schropp, R.E.I.; Cardon, F. Source: Philosophical Magazine B (Physics of Condensed Matter: Statistical Mechanics, Electronic, Optical and Magnetic Properties, v 79, n 2, p 291-318, Feb. 1999 Database: Inspec

10_01_25_Thermally enhanced quantum efficiency in hydrogenated amorphous silicon p-i-n photodiodes studied by intensity- modulated photocurrent spectroscopy

Minority carrier properties of single- and polycrystalline silicon films formed by aluminium-induced crystallisation [solar cells] 2000[edit | edit source]

Abstract:The aluminium-induced crystallisation (AIC) of amorphous silicon is a simple low-temperature method for the growth of thin (5 0.5 pm), ptype (- 2 ~ 1 0 '~~m -s~ing)le - and polycrystalline Si films on Si wafers and foreign substrates, respectively. While previous work has shown that such Si films can be used as thin emitters of p+-n Si wafer cells, this paper investigates the minority carrier diffusion length L, of AIC-grown Si and thus determines whether these films can be used as absorber layer (i.e. base region) of c-Si solar cells. The AIC-grown Si films are made at 460°C on single-crystal n-Si wafers and glass, respectively. By means of current-voltage and quantum efficiency measurements, we show that L, in our AICgrown p'-Si films is only about 100 nm. This is far too low to enable the use of these AIC films as absorber layers in thin-film c-Si solar cells. However, as shown in a companion paper (Harder et a/.), these AIC films are excellent seeding layers on glass that can epitaxially be thickened by suitable Si deposition methods.


Neuhaus, D.H. (Photovoltaics Special Res. Centre, New South Wales Univ., Sydney, NSW, Australia); Bardos, R.; Feitknecht, L.; Puzzer, T.; Keevers, M.J.; Aberle, A.G. Source: Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036), p 65-8, 2000


Recombination mechanisms in amorphous silicon/crystalline silicon heterojunction solar cells 2000[edit | edit source]

Abstract:This article investigates limitations to the open circuit voltage of n-type amorphous silicon/p-type crystalline silicon heterojunction solar cells. The analysis of quantum efficiency and temperature dependent current/voltage characteristics identifies the dominant recombination mechanism. Depending on the electronic quality of the crystalline silicon absorber, either recombination in the neutral bulk or recombination in the space charge region prevails; recombination at the heterointerface is not relevant. Although interface recombination does not limit the open circuit voltage, recombination of photogenerated charge carriers at the heterointerface or in the amorphous silicon emitter diminishes the short circuit current of the solar cells.


Jensen, N. (Inst. fur Phys. Elektronik, Stuttgart Univ., Germany); Rau, U.; Hausner, R.M.; Uppal, S.; Oberbeck, L.; Bergmann, R.B.; Werner, J.H. Source: Journal of Applied Physics, v 87, n 5, p 2639-45, 1 March 2000 Database: Inspec

10_01_25_Recombination mechanisms in amorphous silicon crystalline silicon heterojunction solar cells

Silicon-based materials for optoelectronics: visible photoluminescence and electroluminescence from amorphous silicon 2000[edit | edit source]

Abstract:Room temperature visible photoluminescence (PL) and electroluminescence (EL) of wide band gap hydrogenated amorphous silicon thin films prepared in SiH4 microwave plasma strongly diluted with He is reported. The emission spectra are peaked at approximately 1.5 eV. Films were characterized by means of optical and IR absorption and hydrogen thermal desorption. The band gap of a-Si:H films varies within the interval 2.0-2.2 eV. The strong evidence for two distinct types of PL processes is presented: one being linked with oligosilanes and the second one attributed to electron-hole recombination in tail states. EL has been investigated in p-i-n and p + -p-n-n + structures with CrNi/ITO contacts. The EL occurs after initial forming in reverse bias only and its external quantum efficiency is approximately 10-5 percent. The shape and spectral position of EL spectra suggest that the light emission in this case is probably due to simultaneous excitation of the oligosilane units and impact ionization by hot electrons.


Dian, J. (Fac. of Math. & Phys., Charles Univ., Prague, Czech Republic); Valenta, J.; Poruba, A.; Horvath, P.; Luterova, K.; Fojtik, P.; Pelant, I. Source: Proceedings of the SPIE - The International Society for Optical Engineering, v 4016, p 472-7, 2000

10_01_25_Silicon based materials for optoelectronics visible photoluminescence and electroluminescence from amorphous silicon

Hole diffusion at the recombination junction of thin film tandem solar cells and its effect on the illuminated current-voltage characteristic 2000[edit | edit source]

Abstract:Computer simulation of experimental current density–voltage (J–V) and quantum efficiency characteristics of thin film p1-i1-n1-p2 structures and of double junction solar cells (p1-i1-n1-p2-i2-n2), has been used to understand the hole transport mechanisms near the np "tunnel" junction between two subcells of a multijunction structure. Two different types of p layers at the junction have been studied: (i) hydrogenated microcrystalline silicon (µc-Si:H) and (ii) hydrogenated amorphous silicon carbide (a-SiC:H). There is a striking difference between the experimental J–V characteristics for the p1-i1-n1-p2 structures, with case (i) having a fairly high fill factor (FF) and conversion efficiency (), as against a very low FF and in case (ii). Although the difference is much smaller for double junction cells employing these two types of materials as the p layer at the junction, the fill factor of the cell employing µc-Si:H is about 8% higher. Analysis of transport properties as a function of position by computer modeling reveals that the main difference in behavior between the two cases is due to the much higher free hole population in the p layer at the junction when it is microcrystalline; which in turn, is a direct consequence of the lower activation energy for this case. We also learn that not only tunneling and the electric field in the bottom subcell, but also diffusion, plays a major role in pushing the holes produced in it by the incident light towards the recombination layer at the junction; and thereby helps improve cell performance, especially its fill factor. We conclude that the p layer at the junction should have a high free hole density (low activation energy in the device), to attain an overall high fill factor and conversion efficiency. Another interesting inference is the fact that tunneling as transport mechanism for holes towards the junction is more important when the p layer at the junction is a-SiC:H than when it is microcrystalline, while diffusion plays a more prominent role in propelling holes towards the junction in the latter case.


Palit, N. (Energy Res. Unit, Indian Assoc. for the Cultivation of Sci., Calcutta, India); Dasgupta, A.; Ray, S.; Chatterjee, P. Source: Journal of Applied Physics, v 88, n 5, p 2853-61, 1 Sept. 2000

10_01_25_Hole diffusion at the recombination junction of thin film tandem solar cells and its effect on the illuminated current–voltage characteristic

Optical modeling of a-Si:H solar cells with rough interfaces: Effect of back contact and interface roughness 2000[edit | edit source]

Abstract:An approach to study the optical behavior of hydrogenated amorphous silicon solar cells with rough interfaces using computer modeling is presented. In this approach the descriptive haze parameters of a light scattering interface are related to the root mean square roughness of the interface. Using this approach we investigated the effect of front window contact roughness and back contact material on the optical properties of a single junction a-Si:H superstrate solar cell. The simulation results for a-Si:H solar cells with SnO2:F as a front contact and ideal Ag, ZnO/Ag, and Al/Ag as a back contact are shown. For cells with an absorber layer thickness of 150–600 nm the simulations demonstrate that the gain in photogenerated current density due to the use of a textured superstrate is around 2.3 mA cm–2 in comparison to solar cells with flat interfaces. The effect of the front and back contact roughness on the external quantum efficiency (QE) of the solar cell for different parts of the light spectrum was determined. The choice of the back contact strongly influences the QE and the absorption in the nonactive layers for the wavelengths above 650 nm. A practical Ag back contact can be successfully simulated by introducing a thin buffer layer between the n-type a-Si:H and Ag back contact, which has optical properties similar to Al, indicating that the actual reflection at the n-type a-Si:H/Ag interface is smaller than what is expected from the respective bulk optical parameters. In comparison to the practical Ag contact the QE of the cell can be strongly improved by using a ZnO layer at the Ag back contact or an ideal Ag contact. The photogenerated current densities for a solar cell with a 450 nm thick intrinsic a-Si:H layer with ZnO/Ag and ideal Ag are 16.7 and 17.3 mA cm–2, respectively, compared to 14.4 mA cm–2 for the practical Ag back contact. The effect of increasing the roughness of the contact interfaces was investigated for both superstrate and substrate types of solar cells. Increasing the roughness of the carrier electrode, i.e., the rough electrode on which the silicon cell structure is deposited, up to 35 nm leads to a strong increase in the photogenerated current density; for higher values of the interface roughness the photogenerated current density tends to saturate.


Zeman, M. (Lab. of Electron. Components, Technol. & Mater., Delft Univ. of Technol., Netherlands); van Swaaij, R.A.C.M.M.; Metselaar, J.W.; Schropp, R.E.I. Source: Journal of Applied Physics, v 88, n 11, p 6436-43, 1 Dec. 2000

10_01_25_Optical modeling of a-SiH solar cells with rough interfaces Effect of back contact and interface roughness

Detective quantum efficiency of an X-ray image intensifier chain as a benchmark for amorphous silicon flat panel detectors 2001[edit | edit source]

Abstract:Amorphous silicon flat panel x-ray detectors (A-Si FXD) are expected eventually to replace traditional x-ray image intensifier systems (XRII) in medical radiography in the long term. The advantages of FXD's are their large detection area, no distortion, no sensitivity to magnetic fields, low weight and compactness. However, they do not provide the high sensitivity of specific optimized systems based on image intensifiers, which approach the sensitivity of single x-ray photon counting in an appropriate configuration whereas the noise equivalent number of photons for an a-Si imager is typically several photons at medical energies. That is, the detective quantum efficiency of an XRII at low dose is expected to be higher.


Koch, A. (Thales Electron Devices, Moirans, France); Macherel, J.M.; Wirth, T.; de Groot, P.; Ducourant, T.; Couder, D.; Moy, J.P.; Calais, E. Source: Proceedings of the SPIE - The International Society for Optical Engineering, v 4320, p 115-20, 2001 Database: Inspec

10_01_25_Detective quantum efficiency of an x-ray image intensifier chain as a benchmark for amorphous silicon flat-panal detectors

Development of highly efficient thin film silicon solar cells on texture-etched zinc oxide-coated glass substrates 2001[edit | edit source]

Abstract:ZnO films prepared by magnetron sputtering on glass substrates and textured by post-deposition chemical etching are applied as substrates for p–i–n solar cells. Using both rf and dc sputtering, similar surface textures can be achieved upon etching. Excellent light trapping is demonstrated by high quantum efficiencies at long wavelengths for microcrystalline silicon solar cells. Applying an optimized microcrystalline/amorphous p-layer design, stacked solar cells with amorphous silicon top cells yield similarly high stabilized efficiencies on ZnO as on state-of-the-art SnO2 (9.2% for a-Si/a-Si). The efficiencies are significantly higher than on SnO2-coated float glass as used for module production.


Muller, J. (Inst. of Photovoltaics, Forschungszentrum Julich GmbH, Germany); Kluth, O.; Wieder, S.; Siekmann, H.; Schope, G.; Reetz, W.; Vetterl, O.; Lundszien, D.; Lambertz, A.; Finger, F.; Rech, B.; Wagner, H. Source: Solar Energy Materials and Solar Cells, v 66, n 1-4, p 275-81, Feb. 2001

10_01_25_Development of highly efficient thin film silicon solar cells on texture-etched zinc oxide-coated glass substrates

Modeling the optical quantum efficiency of thin film amorphous silicon solar cells 2001[edit | edit source]

Abstract:The optical quantum efficiency and spectral response of p-i-n thin film amorphous silicon (a-Si:H) solar cells have been modeled using software based on optical admittance analysis. The optical constants of a-Si:H and Indium Tin Oxide (ITO) thin film layers have been measured by Variable Angle Spectroscopic Ellipsometry (VASE) and used as inputs into the optical admittance analysis program in order to model cells constructed from these films. Amorphous silicon thin films and p-i-n assemblies have been deposited by glow discharge and reactive sputtering techniques. The optical constants of doped and intrinsic a-Si:H thin films were determined by VASE, and the film thickness verified by Scanning Electron Microscopy studies. The optical constants of commercially available transparent conducting oxide (TCO) coated substrates have also been determined by VASE. The experimental transmission spectra of p-i-n assemblies are compared with transmission spectra that have been modeled using the measured optical constants. Results of modeling different a-Si:H solar cell structures using these materials are presented, including a study of the optimal TCO layer thickness for p-i-n a-Si:H solar cells. This work shows that optical admittance modeling gives a good prediction of the optical behavior of p-i-n assemblies, but that accurate measurements of the optical constants of the component films are required in order to model effectively the optical quantum efficiency and photocurrent.

Rowlands, S.F. (Electr. & Electron. Eng., Univ. of Western Australia, Perth, WA, Australia); Livingstone, J.; Lund, C.P. Source: Amorphous and Heterogeneous Silicon Thin Films - 2000. Symposium (Materials Research Society Symposium Proceedings Vol.609), p A30.7.1-6, 2001 Database: Inspec

Can't Get.

Optical modelling of thin film solar cells with textured interfaces using the effective medium approximation[edit | edit source]

Abstract:Simple methods for increasing the maximum achievable current density of amorphous silicon (a-Si:H) solar cells include bandgap and layer thickness optimisation, and light confinement strategies. The goal of the optical modelling work presented here has been to examine the nature and potential of these effects, in particular the optical enhancement resulting from the use of finely textured transparent conducting oxides. A computer program that combines coherent and incoherent optical theory has been used as a flexible tool for simulating the performance of any general thin film solar cell structure. An effective medium approximation has been used to model the optical effects of microroughness (texturing with correlation lengths smaller than the wavelength of light). This work suggests that effective interface grading due to microroughness does have a significant effect on the optical performance of a-Si:H solar cells, and that both enhancement and deterioration in the maximum achievable current density can be the outcome. Where both effective interface grading (microroughness) and larger scale texturing (macroroughness) are fully exploited, optical yields may be increased beyond their current level. This work emphasises the importance of characterising and controlling the interface morphology to optimise the short circuit current and maintain the open circuit voltage.


10_01_25_Optical modelling of thin film solar cells with textured interfaces using the effective medium approximation

Performance of a-Si:H photodiode technology-based advanced CMOS active pixel sensor imagers 2001[edit | edit source]

Abstract:Amorphous silicon photodiode technology is a very attractive option for image array integrated circuits because it enables large die-size reduction and higher light collection efficiency than c-Si arrays. The concept behind the technology is to place the photosensing element directly above the rest of the circuit, thus eliminating the need to make areal tradeoffs between photodiode and pixel circuit. We have developed an photodiode array technology that is fully compatible with a 0.35 um CMOS process to produce image sensors arrays with 10-bit dynamic range that are 30% smaller than comparable c-Si photodiode arrays. The work presented here will discuss performance issues and solutions to lend itself to cost-effective high-volume manufacturing. The various methods of interconnection of the diode to the array and their advantages will be presented. The effect of doped layer thickness and concentration on quantum efficiency, and the effect of a-Si:H defect concentration on diode performance will be discussed. The photodiode dark leakage current density is about 80 pA/cm2, and its absolute quantum efficiency peaks about 85% at 550 nm. These sensors have 50% higher sensitivity, and 2x lower dark current when compared to bulk silicon sensors of the same design. The cell utilizes a 3 FET design, but allows for 100% photodiode area due to the elevated nature of the design. The VGA (640 X 480), array demonstrated here uses common intrinsic and p-type contact layers, and makes reliable contact to those layers by use of a monolithic transparent conductor strap tied to vias in the interconnect.

Theil, J.A. (Imaging Electron. Div., Agilent Technol., Santa Clara, CA, USA); Haddad, H.; Snyder, R.D.; Zelman, M.; Hula, D.; Lindahl, K.A. Source: Proceedings of the SPIE - The International Society for Optical Engineering, v 4435, p 206-13, 2001

10_01_26_Performance of a-SiH photodiode technology-based advanced CMOS active pixel sensor imagers

Thin-film UV detectors based on hydrogenated amorphous silicon and its alloys 2001[edit | edit source]

Abstract:Thin film ultraviolet detectors based on hydrogenated amorphous silicon alloys are realized with different diode structures (PIN, NIP, PN, and NP). The PIN and NIP detectors exhibit higher sensitivity in the ultraviolet spectrum and a significant lower dark current in comparison to the PN or NP structures. The best detector performance was achieved with a 33 nm thick PIN diode. This detector shows a maximum of quantum efficiency of 36.3% at a wavelength of 310 nm. By varying the thickness of the semi-transparent Ag front contact the selectivity of the detectors with the quantum efficiency peak at 320 nm can be adjusted. Thus, the spectral sensitivity of the detector shifts from a broad UV to a selective UV-B spectrum.


Krause, M. (Inst. fur Photovoltaik, Forschungszentrum Julich GmbH, Germany); Topic, M.; Stiebig, H.; Wagner, H. Source: Physica Status Solidi A, v 185, n 1, p 121-7, 16 May 2001

10_01_26_Thin-Film UV Detectors Based on Hydrogenated Amorphous Silicon and Its Alloys

Design considerations for a hybrid amorphous silicon/photoelectrochemical multijunction cell for hydrogen production 2003[edit | edit source]

Abstract:Triple-junction amorphous silicon (a-Si) solar cells demonstrating photovoltaic (PV) efficiencies up to 12.7% and open-circuit voltages up to 2.3V have recently been deposited onto stainless-steel foil substrates by the University of Toledo for photoelectrochemical (PEC) tests conducted by the University of Hawaii. The fundamental design strategy for producing such high efficiency in multijunction amorphous silicon devices involves careful current matching in each of the junctions by adjustment of the absorption spectra through bandgap tailoring. Integrated electrical/optical models are frequently used to aid in the optimization procedure, as well documented in the PV literature. Typically, the top nip junction in an a-Si triple-junction cell is designed to absorb most strongly in the 350-500nm range. In principle, this top cell could be replaced by a PEC junction with strong absorption in a similar range to form a water-splitting photoelectrode for hydrogen production. This photoelectrode could be fabricated on SS with the back surface catalyzed for the hydrogen evolution reaction, and the front surface deposited with an a-Si:nipnip/ITO/SC structure. The top layer semiconductor (SC), which forms the PEC junction with an electrolyte, must have appropriate conduction band alignment for the oxygen evolution reaction, and the junction must be strongly absorbing in the 350-500nm region for current matching. Possible candidate SC materials include dye-sensitized titanium dioxide (TiO2), tungsten trioxide (WO3), and iron oxide (Fe2O3). This paper discusses the specific design considerations for high solar-to-hydrogen conversion efficiency in a hybrid solid-state/PEC photoelectrode, and describes the use of integrated electrical/electrochemical/optical models developed at the University of Hawaii for the analysis of such hybrid structures. Important issues include the bias-voltage and current-matching requirements in the solid-state and electrochemical junctions, as well as fundamental quantum efficiency considerations.


Miller, E.L. (Sch. of Ocean & Earth Sci. & Technol., Hawaii Univ., Honolulu, HI, USA); Rocheleau, R.E.; Deng, X.M. Source: International Journal of Hydrogen Energy, v 28, n 6, p 615-23, June 2003

10_01_26_Design considerations for a hybrid amorphous silicon photoelectrochemical multijunction cell for hydrogen production

Quantum Efficiency[edit | edit source]

Abstract:Quantum efficiency (QE) is a figure-of-merit of a photon detector. QE is equal to the percentage of incident photons that are converted by the detector into electrons that constitute a measurable signal. QE applies to detectors spanning a wavelength range from the far infrared (IR) to gamma rays because these are all photons. A detector's QE is affected by many variables: wavelength (of radiation), surface reflectance(s), absorption coefficient(s), layer thickness(es), frequency response, bulk and surface recombination, doping level(s), device configuration, etc.

Early detectors, which were based on the photoelectric effect in metals, required a lot of energy (> workfunction) for a photon to release an electron to vacuum. The advent of semiconductors reduced the energy needed to create photoexcited charge carriers (electrons and holes) because the electrons were only excited from the valence to the conduction band. Initially, silicon (because of its high bandgap energy) allowed operation from the near ultraviolet (UV) to the near infrared (NIR). Later, new low bandgap materials enabled longer wavelength operation, out to the far infrared, and also a wide variety of detectors. Modern detectors fall into three classes: photoconductive (PC) (intrinsic, extrinsic, or quantum well), photovoltaic (PV) diodes (p-n, p-i-n, Schottky barrier, avalanche, and heterojunction), and external photoeffect (photoemissive) photocathodes.

Usually, single element detectors are used for simple detection. For imaging purposes, linear or area arrays of small detectors (size < diffusion length Ldiff) are used. Large single element detectors (size > Ldiff) are effectively infinite, and described by one-dimensional models of QE; small detectors in arrays are finite and require three-dimensional, numerical models for the QE.

This paper is quite good in explaining QE and it gives different cases such as photoconductors, schottky barrier diodes, external photoeffect diodes and quantum well infared detectors. This paper talks about ideal QE devices and how to calculated the QE for devices. However it does not explain what each part of the QE graph tells you.

TY - GEN BT - Encyclopedia of Optical Engineering PB - Taylor & Francis AU - Dhar, Vikram TI - Quantum Efficiency SN - 978-0-8247-0940-2 PY - 2003 SP - 2197 EP - 2218 UR - http://www.informaworld.com/10.1081/E-EOE-120009873


10_01_26_quantum efficiency

Effect of surface roughness of ZnO:Al films on light scattering in hydrogenated amorphous silicon solar cells 2003[edit | edit source]

Abstract:Experimental investigation combined with computer modeling is used for analysis of light scattering process in hydrogenated amorphous silicon (a-Si:H) solar cells deposited on textured glass/ZnO:Al substrates. Descriptive scattering parameters—haze and angular distribution functions (ADFs)—for the textured ZnO:Al films with different surface roughness are determined. The haze parameters of all internal interfaces in the a-Si:H solar cells are calculated using equations of scalar scattering theory calibrated on the measurements of the substrates. The ADFs determined for the substrates are modified and applied to the internal interfaces. The scattering parameters are incorporated in our optical model and used to simulate the effect of the ZnO:Al surface roughness on the quantum efficiency (QE) of the solar cells. The simulations reproduce the measured QE of all solar cells with different roughness of the substrate very well.


Krc, J. (Fac. of Electr. Eng., Ljubljana Univ., Slovenia); Zeman, M.; Kluth, O.; Smole, F.; Topic, M. Source: Thin Solid Films, v 426, n 1-2, p 296-304, 24 Feb. 2003

10_01_26_Effect of surface roughness of ZnOAl films on light scattering in hydrogenated amorphous silicon solar cells

3-dimensional optical model for thin film silicon solar cells 2003[edit | edit source]

Abstract:This paper addresses optical effects in small area thin film silicon p-i-n solar cells deposited on a glass/TCO substrate. An existing one-dimensional model was extended to three dimensions to include the effect of substrate glass thickness and lateral solar cell area. With its help we can model real laboratory cells where the cell dimensions are comparable to the glass thickness. For a quantitative evaluation we compare the external quantum efficiency of an infinitely large solar cell with small area cells. Here the modeling results show increasing differences with increasing glass thickness, decreasing cell area and improving light scattering properties of the TCO. This is explained by internal light trapping in the glass substrate, which causes loss or gain of light intensity absorbed in the cell area. Neglecting such effects can lead to about 11% error in short circuit current density calculated from quantum efficiency measurements.


Springer, J. (Inst. of Phys., Acad. of Sci. of the Czech Republic, Prague, Czech Republic); Poruba, A.; Mullerova, L.; Vanecek, M.; Reetz, W.; Muller, J. Source: Proceedings of 3rd World Conference on Photovoltaic Energy Conversion (IEEE Cat. No.03CH37497), p 1827-30 Vol.2, 2003

10_01_26_3-dimensional optical model for thin film silicon solar cells

Analysis of light scattering in amorphous Si:H solar cells by a one-dimensional semi-coherent optical model 2003[edit | edit source]

Abstract:A one-dimensional semi-coherent optical model for thin-film solar cells is presented. The optical circumstances at flat interfaces are addressed and the situation at rough interfaces in the model is described for the case of direct (coherent) incident and scattered (incoherent) incident light. After the model has been experimentally verified, analysis of the light scattering process in hydrogenated amorphous silicon (a-Si:H) p-i-n solar cells is carried out. The influence of the interface root-mean-square roughness and the effect of different angular distribution functions of diffused light on quantum efficiency and short-circuit current are investigated by the optical model.


Krc, J. (Fac. of Electr. Eng., Ljubljana Univ., Slovenia); Smole, F.; Topic, M. Source: Progress in Photovoltaics: Research and Applications, v 11, n 1, p 15-26, Jan. 2003

10_01_26_Analysis of light scattering in amorphous SiH solar cells by a one-dimensional semi-coherent optical model

Characterization of a 14" × 17" flat panel detector based on ion shower doped a-Si:H PIN diodes 2003[edit | edit source]

Abstract:In recent years it has become technically and economically feasible to use solid-state detector technology to display, store, and transfer x-ray images. In this paper we report the performance of a 33 x 41 cm2 amorphous silicon flat panel detector based on an ion shower doped P-I-N photodiode/TFT array. The p-layer of diode is formed by an ion shower doping method instead of the conventional Plasma Enhanced Chemical Vapor Deposition method. Measurements of x-ray imaging performances are reported with respect to the general imaging metrics, such as modulation transfer function, noise power spectrum, and detective quantum efficiency.


Hee Joon Kim; Gyuseong Cho Source: 2002 IEEE Nuclear Science Symposium Conference Record (IEEE Cat. No.02CH37399), p 931-5 vol.2, 2003

10_01_26_Characterization of a 14" x 17" Flat Panel

Optical modelling of thin-film silicon solar cells deposited on textured substrates 2004[edit | edit source]

Abstract:Optical modelling is used to investigate effects of light scattering in amorphous silicon and microcrystalline silicon solar cells. The role of enhanced haze parameter and different angular distribution function of scattered light is analyzed. Results of optical simulation show that enhanced haze parameter compared to that of Asahi U-type SnO2:F does not improve external quantum efficiency and short-circuit current density of amorphous silicon solar cell significantly, whereas for microcrystalline silicon solar cell the improvement is larger. Angular distribution function affects the external quantum efficiency and the short-circuit current density significantly.


Krc, J. (Fac. of Electr. Eng., Ljubljana Univ., Slovenia); Zeman, M.; Smole, F.; Topic, M. Source: Thin Solid Films, v 451-452, p 298-302, 22 March 2004

10_01_26_Optical modelling of thin-film silicon solar cells deposited on textured substrates

Improved back reflector for high efficiency hydrogenated amorphous and nanocrystalline silicon based solar cells 2005[edit | edit source]

Baojie Yan (United Solar Ovonic Corp., Troy, MI, USA); Owens, J.M.; Chun-Sheng Jiang; Yang, J.; Guha, S. Source: Amorphous and Nanocrystalline Silicon Science and Technology-2005. Symposium (Materials Research Society Symposium Proceedings Vol.862), p 603-8, 2005

Light induced degradation of microcrystalline silicon solar cells 2006[edit | edit source]

Abstract:Microcrystalline silicon solar cells with different crystalline volume fractions (Xc) of intrinsic layer were used to perform light soaking experiments under different light sources. Results showed that the higher Xc of microcrystalline silicon of intrinsic layer is, the less light induced degradation produced in solar cell. According to quantum efficiency (QE) results, the degradation only occurred in the short wavelength range which corresponds to amorphous silicon absorption. A Stabler–Wronski (SW)-like effect associated with the amorphous silicon fraction in microcrystalline silicon is responsible for this degradation.


Yan Wang (Inst. of Photo-Electron. Thin Film Devices & Technique, Nankai Univ., Tianjin, China); Xiaoyan Han; Feng Zhu; Guofu Hou; Huizhi Ren; Kunde Zhang; Junming Xue; Jian Sun; Ying Zhao; Xinhua Geng Source: Journal of Non-Crystalline Solids, v 352, n 9-20, p 1909-12, 15 June 2006

10_01_26_Light induced degradation of microcrystalline silicon solar cells

High performance hydrogenated amorphous silicon n-i-p photo-diodes on glass and plastic substrates by low-temperature fabrication process 2007[edit | edit source]

Kyung Ho Kim (Univ. of Waterloo, Waterloo, Canada); Vygranenko, Y.; Bedzyk, M.; Jeff Hsin Chang; Tsu Chiang Chuang; Striakhilev, D.; Nathan, A.; Heiler, G.; Tredwell, T. Source: Amorphous and Polycrystalline Thin-Film Silicon Science and Technology - 2007, p 481-6, 2007

Internal Quantum Efficiency for Solar Cells 2007[edit | edit source]

Abstract:The total internal quantum efficiency (IQE) of a flat-band p–n homojunction silicon solar cell and contributions of the three regions to it are numerically evaluated. It is found that both the spatial widths of the cell and the surface recombination velocities have significant impacts on the IQEs. By a linear transformation and a proper approximation, the differential equation of the minority carrier density in a textured cell becomes the same form as for the flat cell. What makes differences is that texturization slightly enhances the IQEs for photons with longer wavelengths while notably increasing external quantum efficiency. Hence it plays a good role for getting a better performance of a solar cell. It is considered that the results in the present are of universal technical importance both in designing solar cells and their surface structures.

"On the other hand, the photo-generated current strongly relates to the quantum efficiency (QE). To enhance the conversion efficiency one has to raise the QE. From theoretical aspect, the QE corresponds to the spectral response (SR) which determines the spectral distribution of the short circuit current ISC. By calculating the QE, both the SR and the contributions to the ISC of different wavelengths can be determined, helping one analyze quantum yields from the different cell regions." -paper

doi:10.1016/j.solener.2007.07.010 | How to Cite or Link Using DOI Copyright © 2007 Elsevier Ltd All rights reserved. W.J. Yang, a,, Z.Q. Maa, X. Tanga, C.B. Fenga, W.G. Zhaoa and P.P. Shia

aMicroelectronic Group, Department of Physics, Shanghai University, Shanghai 200444, PR China Received 1 September 2006; revised 10 December 2006; accepted 20 July 2007. Communicated by: Associate Editor T.M. Razykov. Available online 5 September 2007.


10_02_02_Internal Quantum Efficiency for Solar Cells

Optimization of amorphous silicon oxide buffer layer for high-efficiency p-type hydrogenated microcrystalline silicon oxide/n-type crystalline silicon heterojunction solar cells 2008[edit | edit source]

Abstract:Intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H) films deposited by very high frequency plasma-enhanced chemical vapor deposition (60MHz VHF-PECVD) at a low substrate temperature of approximately 200 �C were used as a front buffer layer in p-type hydrogenated microcrystalline silicon oxide/n-type crystalline silicon (p-mc-SiO:H/n-c-Si) heterojunction solar cells. We found that the oxygen concentration in the i-a-SiO:H buffer layer strongly affected the solar cell performance and that the short wavelength response in quantum efficiency (QE) was improved by oxygen addition. Employing a p-mc-SiO:H/i-a-SiO:H/n-Si [Czochralski (CZ), 200 mm, (100)]/i-a-Si:H/n-a-Si:H/Ag/Al configuration, we achieved an efficiency of 17.9% with Voc of 671 mV.


Sritharathikhun, J. (Dept. of Phys. Electron., Tokyo Inst. of Technol., Tokyo, Japan); Yamamoto, H.; Miyajima, S.; Yamada, A.; Konagai, M. Source: Japanese Journal of Applied Physics, v 47, n 11, p 8452-5, Nov. 2008

10_01_26_ Optimization of amorphous silicon oxide buffer layer for high-efficiency p-type hydrogenated microcrystalline silicon oxide n-type crystalline silicon heterojunction solar cells

Modeling of light-induced degradation of amorphous silicon solar cells 2008[edit | edit source]

Abstract:Light-induced degradation of hydrogenated amorphous silicon (a-Si:H) solar cells has been modeled using computer simulations. In the computer model, the creation of light-induced defects as a function of position in the solar cell was calculated using the recombination profile. In this way, a new defect profile in the solar cell was obtained and the performance was calculated again. The results of computer simulations were compared to experimental results obtained on a-Si:H solar cell with different intrinsic layer thickness. These experimental solar cells were degraded under both open- and short-circuit conditions, because the recombination profile in the solar cells could then be altered significantly. A reasonable match was obtained between the experimental and simulation results if only the mid-gap defect density was increased. To our knowledge, it is the first time that light-induced degradation of the performance and the quantum efficiency of a thickness series of a-Si:H solar cells has been modeled at once using computer simulations.


Klaver, A. (Delft Univ. of Technol., Delft, Netherlands); van Swaaij, R.A.C.M.M. Source: Solar Energy Materials and Solar Cells, v 92, n 1, p 50-60, Jan. 2008

10_01_26_Modeling of light-induced degradation of amorphous silicon solar cells

Substrate engineering for high efficiency thin film solar cells 2008[edit | edit source]

Abstract:The design considerations for a spectra modifying, light scattering layer for amorphous silicon solar cells were investigated. Efficient commercially available phosphors absorb one near IR photon and one near UV photon and emit one photon in the visible spectrum. Thereby such phosphors offer the possibility to convert two poorly utilized portions of the solar spectrum to photons that are converted to electric energy with high quantum efficiency in amorphous silicon-based solar cells. Large band gap, conductive, a-SiC:H and a-SiN:H are attractive matrices for phosphors as scattered light and emitted photons are thereby directed towards the underlying solar cell structure.


Mawyin, J.A. (Stony Brook Univ., Stony Brook, USA); Chawda, S.G.; Halada, G.P.; Clayton, C.R.; Tonucci, R.J.; Fortmann, C.M. Source: Journal of Non-Crystalline Solids, v 354, n 19-25, p 2492-4, 1 May 2008

10_01_26_Substrate engineering for high efficiency thin film solar cells

A comparison of fill factor and recombination losses in amorphous silicon solar cells on ZnO and SnO2 2009[edit | edit source]

Abstract:Effects of ZnO and SnO2 TCO (Transparent Conductive Oxide) substrate materials on hydrogenated amorphous silicon (a-Si:H) p-i-n solar cell performances and recombination kinetics have been investigated. DC and Frequency-resolved photocurrent measurements in a-Si:H p-i-n solar cells of 6 have been carried out experimentally. In particular, the I–V characteristics in the dark and light, the quantum efficiency spectra, the intensity-, bias voltage- and frequency-dependence of photocurrent were obtained. Fill factor (FF) values were determined from I–V characteristics for both types of substrate cells under various illumination levels. The exponent v in the power–law relationship, Iph α Gv, between generating flux density and photocurrent were determined at different bias voltages (DC) and modulation frequencies. High values of Voc (open-circuit voltage), FF, and DC exponent v for the a-Si:H p-i-n solar cell with SnO2 were obtained, but the integrated QE (quantum efficiency), the modulated exponent v were found to be low compared to cells prepared on ZnO substrates. Our results show that these parameters are sensitive to the ZnO and SnO2 substrate materials which act as a window layer allowing most of the incident light to pass into the i-layer of p-i-n cells.


Alkaya, A. (Dept. of Electr.-Electron. Eng., Univ. of Mersin, Mersin, Turkey); Kaplan, R.; Canbolat, H.; Hegedus, S.S. Source: Renewable Energy, v 34, n 6, p 1595-9, June 2009

10_01_26_A comparison of fill factor and recombination losses in amorphous silicon solar cells on ZnO and SnO2

2D modeling of silicon based thin film dual and triple junction solar cells 2009[edit | edit source]

Abstract:Based on Crosslight APSYS, thin film amorphous Si (a-Si:H)/microcrystalline (µc-Si) dual-junction (DJ) and a- Si:H/amorphous SiGe:H (a-SiGe:H)/µc-Si triple-junction (TJ) solar cells are modeled. Basic physical quantities like band diagrams, optical absorption and generation are obtained. Quantum efficiency and I-V curves for individual junctions are presented for current matching analyses. The whole DJ and TJ cell I-V curves are also presented and the results are discussed with respect to the top surface ZnO:Al TCO layer affinity. The interface texture effect is modeled with FDTD (finite difference time domain) module and results for top junction are presented. The modeling results give possible clues to achieve high efficiency for DJ and TJ thin film solar cells.

Xiao, Y.G. (Crosslight Software Inc., Burnaby, BC, Canada); Uehara, K.; Lestrade, M.; Li, Z.Q.; Li, Z.M.S. Source: Proceedings of the SPIE - The International Society for Optical Engineering, v 7409, p 74090F (8 pp.), 2009

10_01_26_2D modeling of silicon based thin film dual and triple junction solar cells

Quantum efficiency of light-induced defect creation in hydrogenated amorphous silicon and amorphous As2Se3 2004[edit | edit source]

Abstract:The quantum efficiency (QE) of light-induced metastable defect creation in hydrogenated amorphous silicon (a-Si: H) and amorphous As2Se3 (a-As2Se3) by bandgap and subgap illumination has been deduced from photocurrent measurements. The QE decreases with increasing number of absorbed photons. A higher QE for a-As2Se3 than for a-Si: H has been observed and this is interpreted in terms of the higher structural flexibility of a-As2Se3. We have also found that, for both materials, subgap illumination yields a higher QE than does bandgap illumination.


Shimakawa, K. (Dept. of Electr. & Electron. Eng., Gifu Univ., Japan); Meherun-Nessa; Ishida, H.; Ganjoo, A. Source: Philosophical Magazine, v 84, n 1, p 81-9, 1 Jan. 2004 Database: Inspec

10_01_26_Quantum efficiency of light-induced defect creation in hydrogenated amorphous silicon and amorphous As2Se3

Exergy[edit | edit source]

Annual exergy evaluation on photovoltaic-thermal hybrid collector 1997[edit | edit source]

Abstract: In this study, we designed and constructed a photovoltaic-thermal hybrid collector on our campus. The collector consisted of a liquid heating fiat-plate solar collector with mono-Si PV cells on substrate of non-selective aluminum absorber plate, The collector area was 1.3 x 0.5 m [1]. Since electrical and thermal energy are different in nature, it is necessary to take into account the nature of the energy in evaluating or comparing them. For this, we adopted concepts based on the exergy theory. From our annual experimental evaluation based on exergy, we are concluding that the PV/T collector can produce higher output density than a unit PV module or liquid heating fiat-plate solar collector.


Exergy Efficient Production, Storage and Distribution of Solar Energy 2003 THESIS[edit | edit source]

Abstract: Effective energy management must not only consider how much energy is needed to perform a certain task, but also what type of energy is actually required. The energy demand by application area in residential buildings in the EU countries is shown in Figure 1.1 (European Commission, 2000). Space heating and hot water represent the largest demand, and the required energy is "low quality" heat characterized by obtaining temperature differences in the range of 10 – 50 °C. In the industrialized world this demand for low temperature heat is usually covered by consuming "high quality" resources such as fossil fuels, which are both limited in abundance and have a negative effect on the global environment. Our future energy system must to a larger extent be based on renewable and clean energy resources and carriers, and, since the access to high quality energy is limited, these resources must be reserved for applications where high quality energy is actually required. Demands for low quality, low temperature heat on the other hand, can successfully be covered by utilizing correspondingly low quality energy resources.

The work presented in this thesis represents a small contribution to the ongoing research aiming to develop effective ways of utilizing thermal energy, solar heat in particular, thereby replacing the consumption of high quality resources for low quality purposes. More specifically, the thesis addresses the effectiveness at which exergy is managed through the stages of solar heat production, storage, and distribution, and investigates the integration of new technologies in an exergy efficient low temperature heating system. Exergy is a measure of the quality associated with a particular source of energy, or how much work can be withdrawn in a reversible process. A second main topic is long term storage of thermal energy as latent heat in supercooled liquids. Supercooled substances in thermal equilibrium with the surroundings experiences no further heat loss, and the stored latent heat can be retrieved on demand at a later time. A limited amount of previous work has been documented on this topic. The thesis therefore gives an overview over important factors for potential supercooling heat storage applications, while probing deeper into the issues of quantifying the heat storage capacity and also how the crystallization of a supercooled liquid can be triggered in a controlled manner.

10_04_28_Exergy Efficient Production, Storage and Distribution of solar energy.pdf

Performance of a concentrating photovoltaic/thermal solar collector 2005[edit | edit source]

Abstract: The performance of a parabolic trough photovoltaic/thermal collector with a geometric concentration ratio of 37· is described. Measured results under typical operating conditions show thermal efficiency around 58% and electrical efficiency around 11%, therefore a combined efficiency of 69%. The impact of non-uniform illumination on the solar cells is investigated using purpose built equipment that moves a calibrated solar cell along the line of the receiver and measures short circuit current. The measured illumination flux profile along the length shows significant variation, despite the mirror shape error being less than 1 mm for most of the mirror area. The impact of the illumination nonuniformities due to the shape error, receiver support post shading and gaps between the mirrors is shown to have a significant effect on the overall electrical performance. The flux profile transverse to the receiver length is also investigated. Peak flux intensities are shown to be around 100 suns. The impact on efficiency due to open circuit voltage reduction is discussed.


Performance evaluation of photovoltaic thermal solar air collector for composite climate in India 2005[edit | edit source]

Abstract:The objective of present study is to evaluate the performance of the photovoltaic (PV) module integrated with air duct for composite climate of India. In this case, thermal energy is produced along with electrical energy generated by a PV module with higher efficiency. An analytical expression for an overall efficiency (electrical and thermal) has been derived by using energy balance equation for each component. Experimental validation of thermal model of hybrid photovoltaic/thermal (PV/T) system has also been carried out. It has been observed that there is a fair agreement between theoretical and experimental observations. Further it is concluded that an overall thermal efficiency of PV/T system is significantly increased due to utilization of thermal energy in PV module.

10_04_28_Performance evaluation of photovoltaic thermal solar air collector for composite climate of India.pdf

Energy and exergy efficiencies of a hybrid photovoltaic–thermal air collector 2006[edit | edit source]

Abstract:In this communication, an attempt has been made to evaluate exergy analysis of a hybrid photovoltaic–thermal (PV/T) parallel plate air collector for cold climatic condition of India (Srinagar). The climatic data of Srinagar for the period of four years (1998–2001) has been obtained from Indian Metrological Department (IMD), Pune, India. Based on the data four climatic conditions have been defined. The performance of a hybrid PV/T parallel plate air collector has been studied for four climatic conditions and then exergy efficiencies have been carried out. It is observed that an instantaneous energy and exergy efficiency of PV/T air heater varies between 55–65 and 12–15%, respectively. These results are very close to the results predicted by Bosanac et al. [Photovoltaic/thermal solar collectors and their potential in Denmark. Final Report, EFP Project, 2003, 1713/00-0014, www.solenergi.dk/rapporter/pvtpotentialindenmark.pdf].

10_04_28_Energy and exergy efficiencies of a hybrid photovoltaic–thermal air collector.pdf

Quantifying global exergy resources 2006[edit | edit source]

Abstract:Exergy is used as a common currency to assess and compare the reservoirs of theoretically extractable work we call energy resources. Resources consist of matter or energy with properties different from the predominant conditions in the environment. These differences can be classified as physical, chemical, or nuclear exergy. This paper identifies the primary exergy reservoirs that supply exergy to the biosphere and quantifies the intensive and extensive exergy of their derivative secondary reservoirs, or resources. The interconnecting accumulations and flows among these reservoirs are illustrated to show the path of exergy through the terrestrial system from input to its eventual natural or anthropogenic destruction. The results are intended to assist in evaluation of current resource utilization, help guide fundamental research to enable promising new energy technologies, and provide a basis for comparing the resource potential of future energy options that is independent of technology and cost.


Energy, exergy, and Second Law performance criteria 2007[edit | edit source]

Abstract: Performance criteria, such as efficiencies and coefficients of performance, for energy systems, are commonly used but often without sufficient understanding and consistence. The situation becomes particularly incoherent when simultaneous energy interactions of different types, such as work, heating and cooling, take place with a system. Also, the distinction between exergy and Second Law efficiencies is not clearly recognized by many. It is attempted here to clarify the definitions and use of energy and exergy based performance criteria, and of the Second Law efficiency, with an aim at the advancement of international standardization of these important concepts.


Industrial application of PV/T solar energy systems 2007[edit | edit source]

Abstract: Hybrid photovoltaic/thermal (PV/T) systems consist of PV modules and heat extraction units mounted together. These systems can simultaneously provide electrical and thermal energy, thus achieving a higher energy conversion rate of the absorbed solar radiation than plain photovoltaics. Industries show high demand of energy for both heat and electricity and the hybrid PV/T systems could be used in order to meet this requirement. In this paper the application aspects in the industry of PV/T systems with water heat extraction is presented. The systems are analyzed with TRNSYS program for three locations Nicosia, Athens and Madison that are located at different latitudes. The system comprises 300 m2 of hybrid PV/T collectors producing both electricity and thermal energy and a 10 m3 water storage tank. The work includes the study of an industrial process heat system operated at two load supply temperatures of 60 �C and 80 �C. The results show that the electrical production of the system, employing polycrystalline solar cells, is more than the amorphous ones but the solar thermal contribution is slightly lower. A non-hybrid PV system produces about 25% more electrical energy but the present system covers also, depending on the location, a large percentage of the thermal energy requirement of the industry considered. The economic viability of the systems is proven, as positive life cycle savings are obtained in the case of hybrid systems and the savings are increased for higher load temperature applications. Additionally, although amorphous silicon panels are much less efficient than the polycrystalline ones, better economic figures are obtained due to their lower initial cost, i.e., they have better cost/benefit ratio.


Performance evaluation of a hybrid photovoltaic thermal (glass to glass) system 2008[edit | edit source]

Abstract:In this paper, an attempt is made to evaluate the thermal performance of a hybrid photovoltaic thermal (PV/T) air collector system. The two type of photovoltaic (PV) module namely PV module with glass-to-tedlar and glass-to-glass are considered for performance comparison. The results of both PV modules are compared for composite climate of New Delhi. Analytical expression for solar cell, back surface, outlet air temperatures and an overall thermal efficiency are derived for both cases. It is observed that hybrid air collector with PV module glass-to-glass gives better performance in terms of overall thermal efficiency. Parametric studies are also carried out.

10_04_28_Performance evaluation of a hybrid photovoltaic thermal (glass-to-glass) system.pdf

An experimental study on energy generation with a photovoltaic (PV)– solar thermal hybrid system 2008[edit | edit source]

Abstract: A hybrid system, composed of a photovoltaic (PV) module and a solar thermal collector is constructed and tested for energy collection at a geographic location of Cyprus. Normally, it is required to install a PV system occupying an area of about 10m2 in order to produce electrical energy; 7 kWh/day, required by a typical household. In this experimental study, we used only two PV modules of area approximately

  1. 6m2 (i.e., 1.3�0.47m2) each. PV modules absorb a considerable amount of solar radiation that

generate undesirable heat. This thermal energy, however, may be utilized in water pre-heating applications. The proposed hybrid system produces about 2.8kWh thermal energy daily. Various attachments that are placed over the hybrid modules lead to a total of 11.5% loss in electrical energy generation. This loss, however, represents only 1% of the 7kWh energy that is consumed by a typical household in northern Cyprus. The pay-back period for the modification is less than 2 years. The low investment cost and the relatively short pay-back period make this hybrid system economically attractive.


Performance characteristics and energy–exergy analysis of solar-assisted heat pump system 2008[edit | edit source]

Abstract: In this study solar-assisted heat pump (SAHP) system with flat plate collectors was investigated experimentally and tested for domestic space heating. SAHP system was located in a test room with 60m2 floor area in Firat University, Elazig (38,411N, 39,141E) Turkey. The experiments were performed in heating season of January 2003. The coefficient of performance of the SAHP system was calculated. The system COP of the SAHP was obtained as 3.08 while the exergy loss of the solar collector was found to be 1.92 kW. The second law efficiency of the compressor, condenser, evaporator and solar heat exchanger in SAHP system were evaluated 42.1%, 83.7%, 43.2% and 9.4%, respectively. The first law efficiency and exergetic efficiency of the whole system are found to be 65.6%, 30.8%, respectively. Consequently the energy and exergy loss analysis results show that the COP increase when the exergy loss of evaporator decrease.


An improved thermal and electrical model for a solar photovoltaic thermal air collector 2009[edit | edit source]

Abstract:In this paper, an attempt is made to investigate the thermal and electrical performance of a solar photovoltaic thermal (PV/T) air collector. A detailed thermal and electrical model is developed to calculate the thermal and electrical parameters of a typical PV/T air collector. The thermal and electrical parameters of a PV/T air collector include solar cell temperature, back surface temperature, outlet air temperature, open-circuit voltage, short-circuit current, maximum power point voltage, maximum power point current, etc. Some corrections are done on heat loss coefficients in order to improve the thermal model of a PV/T air collector. A better electrical model is used to increase the calculations precision of PV/T air collector electrical parameters. Unlike the conventional electrical models used in the previous literature, the electrical model presented in this paper can estimate the electrical parameters of a PV/T air collector such as open-circuit voltage, short-circuit current, maximum power point voltage, and maximum power point current. Further, an analytical expression for the overall energy efficiency of a PV/T air collector is derived in terms of thermal, electrical, design and climatic parameters. A computer simulation program is developed in order to calculate the thermal and electrical parameters of a PV/T air collector. The results of numerical simulation are in good agreement with the experimental measurements noted in the previous literature. Finally, parametric studies have been carried out. Since some corrections have been down on thermal and electrical models, it is observed that the thermal and electrical simulation results obtained in this paper is more precise than the one given by the previous literature. It is also found that the thermal efficiency, electrical efficiency and overall energy efficiency of PV/T air collector is about 17.18%, 10.01% and 45%, respectively, for a sample climatic, operating and design parameters.

10_04_28_An improved thermal and electrical model for a solar photovoltaic thermal air collector.pdf

How much exergy one can obtain from incident solar radiation? 2009[edit | edit source]

Abstract:A thermodynamic model is proposed to study the exergetic content of incident solar radiation reaching on the Earth's surface which can be used to produce work through a dually cascaded thermodynamic cycle. The "topping" cycle is an ad hoc engine created by nature that connects the outer shell of the terrestrial atmosphere �which is in equilibrium with the extraterrestrial solar radiation� to the collector of a solar heat engine operating on the Earth's surface. The work produced by the topping cycle is dissipated in form of scattering, absorption, heat, movement of air masses �wind�, etc. The "bottoming" cycle is a heat engine operating between the collector and surrounding temperatures, and delivers useful work. It is shown that the maximum work extractable from this system as exergy is obtained when both cycles operate reversibly. An expression for this maximum work, which represents the exergy of incident solar radiation on the Earth's surface, is proposed. The application of the present model is illustrated and validated by calculating the exergy of solar radiation based on some measurements. The results obtained by the present model are compared to the ones obtained through other models available in the open literature.

10_04_28_How much exergy one can obtain from incident solar radiation.pdf

Analysis of terrestrial solar radiation exergy 2009[edit | edit source]

Abstract: Based on Candau's definition of radiative exergy, the exergy of the extraterrestrial and the terrestrial solar radiation are computed and compared by using the solar spectral radiation databank developed by Gueymard. The results show that within the spectrum region from

  1. 28 to 4.0 lm, the total energy quality factor (i.e., the exergy-to-energy ratio) of extraterrestrial solar radiation is about 0.9292, and that

of the global terrestrial solar radiation is about 0.9171 under US standard atmosphere condition and zero solar zenith angle. The terrestrial solar spectral radiation exergy flux is large in the near ultraviolet and the visible light region. The reference radiation exergy spectra are obtained under atmospheric conditions consistent with ASTM standard G173-03. The effect of tilt angle on the terrestrial solar radiative exergy for inclined surface, and the effect of air mass on total energy quality factor of the terrestrial solar radiation for horizontal surface are analyzed. With the increase of tilt angle, the terrestrial solar spectral radiation exergy flux initially increases and then decreases, the total energy quality factor of the diffuse part decreases monotonically, while that of the direct part is invariant. The total energy quality factor of the direct, the diffuse and the global terrestrial solar radiation all decrease with the increase of air mass.


Energy and exergy analysis of photovoltaic–thermal collector with and without glass cover 2009[edit | edit source]

Abtract: In photovoltaic–thermal (PV/T) technology, the use of glass cover on the flat-plate hybrid solar collector is favorable to the photothermic process but not to the photovoltaic process. Because of the difference in the usefulness of electricity and thermal energy, there is often no straight forward answer on whether a glazed or unglazed collector system is more suitable for a specific application. This glazing issue was tackled in this paper from the viewpoint of thermodynamics. Based on experimental data and validated numerical models, a study of the appropriateness of glass cover on a thermosyphon-based water-heating PV/T system was carried out. The influences of six selected operating parameters were evaluated. From the first law point of view, a glazed PV/T system is found always suitable if we are to maximize the quantity of either the thermal or the overall energy output. From the exergy analysis point of view however, the increase of PV cell efficiency, packing factor, water mass to collector area ratio, and wind velocity are found favorable to go for an unglazed system, whereas the increase of on-site solar radiation and ambient temperature are favorable for a glazed system.


Exergy analysis of integrated photovoltaic thermal solar water heater under constant flow rate and constant collection temperature modes 2009[edit | edit source]

Abtract: In this communication, an analytical expression for the water temperature of an integrated photovoltaic thermal solar (IPVTS) water heater under constant flow rate hot water withdrawal has been obtained. Analysis is based on basic energy balance for hybrid flat plate collector and storage tank, respectively, in the terms of design and climatic parameters. Further, an analysis has also been extended for hot water withdrawal at constant collection temperature. Numerical computations have been carried out for the design and climatic parameters of the system used by Huang et al. [Huang BJ, Lin TH, Hung WC, Sun FS. Performance evaluation of solar photovoltaic/thermal systems. Sol Energy 2001; 70(5): 443–8]. It is observed that the daily overall thermal efficiency of IPVTS system increases with increase constant flow rate and decrease with increase of constant collection temperature. The exergy analysis of IPVTS system has also been carried out. It is further to be noted that the overall exergy and thermal efficiency of an integrated photovoltaic thermal solar system (IPVTS) is maximum at the hot water withdrawal flow rate of

  1. 006 kg/s. The hourly net electrical power available from the system has also been evaluated.


Performance analysis of photovoltaic systems: A review 2009[edit | edit source]

Abstract: In this paper, a thorough review of photovoltaic and photovoltaic thermal systems is done on the basis of its performance based on electrical as well as thermal output. Photovoltaic systems are classified according to their use, i.e., electricity production and thermal applications along with the electricity production. The application of various photovoltaic systems is also discussed in detail. The performance analysis including all aspects, e.g., electrical, thermal, energy, and exergy efficiency are also discussed. A case study for PV and PV/T system based on exergetic analysis is presented.


Thermodynamic assessment of photovoltaic systems 2009[edit | edit source]

Abstract: In this paper, an attempt is made to investigate the performance characteristics of a photovoltaic (PV) and photovoltaic-thermal (PV/ T) system based on energy and exergy efficiencies, respectively. The PV system converts solar energy into DC electrical energy where as, the PV/T system also utilizes the thermal energy of the solar radiation along with electrical energy generation. Exergy efficiency for PV and PV/T systems is developed that is useful in studying the PV and PV/T performance and possible improvements. Exergy analysis is applied to a PV system and its components, in order to evaluate the exergy flow, losses and various efficiencies namely energy, exergy and power conversion efficiency. Energy efficiency of the system is calculated based on the first law of thermodynamics and the exergy efficiency, which incorporates the second law of thermodynamics and solar irradiation exergy values, is also calculated and found that the latter is lower for the electricity generation using the considered PV system. The values of fill factor" are also determined for the system and the effect of the fill factor on the efficiencies is also evaluated. The experimental data for a typical day of March (27th March 2006) for New Delhi are used for the calculation of the energy and exergy efficiencies of the PV and PV/T systems. It is found that the energy efficiency varies from a minimum of 33% to a maximum of 45% respectively, the corresponding exergy efficiency (PV/T) varies from a minimum of 11.3% to a maximum of 16% and exergy efficiency (PV) varies from a minimum of 7.8% to a maximum of 13.8%, respectively.


A review on photovoltaic/thermal hybrid solar technology 2010[edit | edit source]

Abstract:A significant amount of research and development work on the photovoltaic/thermal (PVT) technology has been done since the 1970s. Many innovative systems and products have been put forward and their quality evaluated by academics and professionals. A range of theoretical models has been introduced and their appropriateness validated by experimental data. Important design parameters are identified. Collaborations have been underway amongst institutions or countries, helping to sort out the suitable products and systems with the best marketing potential. This article gives a review of the trend of development of the technology, in particular the advancements in recent years and the future work required.


Enhancing the performance of building integrated photovoltaics 2010[edit | edit source]

Abstract:Recent research in Building Integrated Photovoltaics (BIPV) is reviewed with the emphases on a range of key systems whose improvement would be likely to lead to improved solar energy conversion efficiency and/or economic viability. These include invertors, concentrators and thermal management systems. Advances in techniques for specific aspects of systems design, installation and operation are also discussed.


Optimizing the energy and exergy of building integrated photovoltaic thermal (BIPVT) systems under cold climatic conditions 2010[edit | edit source]

Abtract: Building integrated photovoltaic thermal (BIPVT) system has the potential to become a major source of renewable energy in the urban environment. In this paper, the system has been used as the roof top of a building to generate higher electrical energy per unit area and to produce necessary thermal energy required for space heating. One-dimensional transient model has been developed using basic heat transfer equations. On the basis of this model, an analysis has been carried in order to select an appropriate BIPVT system suitable for the cold climatic conditions of India. The PV performances, net energy gain and exergy of the building are determined. The results show that for a constant mass flow rate of air the system connected in series gives a better performance whereas for a constant velocity of air flow the system connected in parallel gives a better performance. The BIPVT system, fitted on the rooftop in an effective area of 65 m2, is capable of annually producing the net electrical and thermal exergies of 16,209 kW h and 1531 kW h, respectively, at an overall thermal efficiency of 53.7%.


Photovoltaic thermal module concepts and their performance analysis: A review 2010[edit | edit source]

Abstract: This paper presents a review of the available literature covering the latest module aspects of different photovoltaic/thermal (PV/T) collectors and their performances in terms of electrical as well as thermal output. The review covers detailed description of flat-plate and concentrating PV/T systems, using liquid or air as the working fluid, numerical model analysis, experimental work and qualitative evaluation of thermal and electrical output. Also an in-depth review on the performance parameters such as, optimum mass flow rate, PV/T dimensions, air channel geometry is presented in this study. Based on the thorough review, it is clear that PV/T modules are very promising devices and there exists lot of scope to further improve their performances. Appropriate recommendations are made which will aid PV/T systems to improve their efficiency and reducing their cost, making them more competitive in the present market.


Thermal radiation and the second law 2010[edit | edit source]

Abstract: The purpose of this paper is to collect and interrelate the fundamental concepts about second law analysis of thermal radiation. This heat transfer mode plays a leading role in solar energy utilization and in high-temperature devices, representing a significant contribution to irreversibility that is frequently omitted in engineering analysis. Entropy and exergy of thermal radiation are reviewed first. Radiative transfer processes are reviewed next, including exchange between surfaces, the presence of a participative medium, and the analysis of combined heat transfer modes. Emphasis is put on grey body radiation when treating with non-black body radiation, due to its relevance in engineering applications. The mathematical formulation of second law analysis of thermal radiation is complex, which limits its use in conventional heat transfer analysis. For this reason, numerical approaches reported to date deal with quite simple cases, leaving an open promising field of research.


Glossary[edit | edit source]

Staebler-Wronski effect: When light interacts with the amorphous silicon cell, the light changes the cell's properties by light induced metaphase changes. The damage can be reversed if the cell is heated above 150 C.

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