Comparison of Prolonged Light Soaking of Single and Stacked Junction A-SI:H Solar Cells

1989 ◽  
Vol 149 ◽  
Author(s):  
P. Lechner ◽  
B. Scheppat ◽  
R. Geyer ◽  
H. Rübel ◽  
M. Gorn ◽  
...  

ABSTRACTLight-induced degradation of a-Si solar cells is dependent on their design. The degradation rate for single cells increases with i-layer thickness. Very thin i-layer devices (d < 100 nm) exhibit a delayed onset of degradation which is accompanied by a severe loss of open circuit voltage at prolonged exposure times. By extrapolating i-layer thickness to zero and therefore separating bulk and interface effects, the latter may account for a substantial loss of stability. The introduction of a SiC buffer layer at the p/i interface results in a considerable higher degradation mainly caused by a loss in fill factor.Double stacked cells, as compared to single cells having similar initial efficiences, show higher stability. The instability at extended exposure times of very thin single cells as used in a tandem configuration did not influence the stacked device.

2014 ◽  
Vol 665 ◽  
pp. 111-114 ◽  
Author(s):  
Ying Huang ◽  
Xiao Ming Shen ◽  
Xiao Feng Wei

In this paper, InAlN/Si single-heterojunction solar cells have been theoretically simulated based on wxAMPS software. The photovoltaic parameters, such as open circuit voltage, short circuit current, fill factor and conversion efficiency were investigated with changing the indium content and thickness of n-InAlN layer. Simulation results show that the optimum efficiency of InAlN/Si solar cells is 23.1% under AM 1.5G spectral illuminations, with the indium content and thickness of n-InAlN layer are 0.65 and 600nm, respectively. The simulation would contribute to design and fabricate high efficiency InAlN/Si solar cells in experiment.


1986 ◽  
Vol 70 ◽  
Author(s):  
F. R. Jeffrey ◽  
G. D. Vernstrom ◽  
M. Weber ◽  
K. A. Epstein

ABSTRACTwe have studied the effects of intrinsic layer dopant profiles on the open circuit voltage and fill factor of p-i-n and n-i-p solar cells. Data is presented showing that boron profiling into the i-layer is responsible for the commonly observed difference in open circuit voltage between p-i-n and n-i-p devices. As only a shallow profile is required to produce this effect, it is proposed that the lower Voc samples are being limited by surface recombination at the p/i interface and that the boron profile reduces this recombination current. The fill factor for devices illuminated through the n+ layer is shown to be very sensitive to the depth of a boron profile, yet not so sensitive to the profile concentration. A maximum occurs for a profile penetrating slightly more than half way through the cell. Spectral response data clearly shows a shifting of high collection from the back to the front of the cell.


2003 ◽  
Vol 762 ◽  
Author(s):  
Jianhua Zhu ◽  
Vikram L. Dalal

AbstractWe report on the growth and properties of microcrystalline Si:H and (Si,Ge):H solar cells on stainless steel substrates. The solar cells were grown using a remote, low pressure ECR plasma system. In order to crystallize (Si,Ge), much higher hydrogen dilution (∼40:1) had to be used compared to the case for mc-Si:H, where a dilution of 10:1 was adequate for crystallization. The solar cell structure was of the p+nn+ type, with light entering the p+ layer. It was found that it was advantageous to use a thin a-Si:H buffer layer at the back of the cells in order to reduce shunt density and improve the performance of the cells. A graded gap buffer layer was used at the p+n interface so as to improve the open-circuit voltage and fill factor. The open circuit voltage and fill factor decreased as the Ge content increased. Quantum efficiency measurements indicated that the device was indeed microcrystalline and followed the absorption characteristics of crystalline ( Si,Ge). As the Ge content increased, quantum efficiency in the infrared increased. X-ray measurements of films indicated grain sizes of ∼ 10nm. EDAX measurements were used to measure the Ge content in the films and devices. Capacitance measurements at low frequencies ( ~100 Hz and 1 kHz) indicated that the base layer was indeed behaving as a crystalline material, with classical C(V) curves. The defect density varied between 1x1016 to 2x1017/cm3, with higher defects indicated as the Ge concentration increased.


2013 ◽  
Vol 117 (39) ◽  
pp. 19866-19874 ◽  
Author(s):  
James W. Ryan ◽  
Thomas Kirchartz ◽  
Aurélien Viterisi ◽  
Jenny Nelson ◽  
Emilio Palomares

2000 ◽  
Vol 609 ◽  
Author(s):  
T. Brammer ◽  
H. Stiebig ◽  
A. Lambertz ◽  
W. Reetz ◽  
H. Wagner

ABSTRACTThe optoelectronic behavior of diodes deposited by plasma enhanced chemical vapor deposition was investigated for a series of different silane concentrations in the gas phase. The purpose of this work was to correlate device characteristics with inherent properties of microcrystalline silicon by experiments and numerical simulations. Dark diode characteristics and, therefore, the open circuit voltage behavior of this series were dominated by the bulk properties of the i-layer (equilibrium carrier concentration) as shown by numerical modeling. Measurement of the solar cell output parameters as a function of the temperature showed that the fill factor of solar cells with small silane concentrations is dominated by the dark diode characteristics. This is in contrast to the temperature dependent fill factor of solar cells with large silane concentration which is limited by the extraction efficiency of the photogenerated carriers. Interface effects dominated the temperature dependent blue response. The gain in blue response increased with temperature and silane concentration by up to 200 % which revealed transport limiting material properties in the vicinity of the p/i-interface. This behavior was attributed to the nucleation region.


2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Marcel M. Said ◽  
Yadong Zhang ◽  
Raghunath R. Dasari ◽  
Dalaver H. Anjum ◽  
Rahim Munir ◽  
...  

AbstractPoly(3-hexylthiophene) (P3HT) films and P3HT / fullerene photovoltaic cells have been p-doped with very low levels (< 1 wt. %) of molybdenum tris[1-(trifluoromethylcarbonyl)- 2-(trifluoromethyl)-ethane-1,2-dithiolene]. The dopants are inhomogenously distributed within doped P3HT films, both laterally and as a function of depth, and appear to aggregate in some instances. Doping also results in subtle changes in the local and long range order of the P3HT film. These effects likely contribute to the complexity of the observed evolutions in conductivity, mobility and work function with doping levels. They also negatively affect the open-circuit voltage and fill factor of solar cells in unexpected ways, indicating that dopant aggregation and non-uniform distribution can harm device performance.


1998 ◽  
Vol 507 ◽  
Author(s):  
Frank Siebke ◽  
Shigeo Yata ◽  
Yoshihiro Hishikawa ◽  
Makoto Tanaka

ABSTRACTWe investigated p-i-n solar cells with microcrystalline absorber but amorphous contact layers. Fill factor and open circuit voltage depend sensitively on the p/i interface. Using an optimized design of the p/i interface, cells with fill factors up to 65% and open circuit voltages of 0.45 V were deposited on amorphous p-layers. They are comparable to cells on micro- crystalline p-layers. A further increase of the open circuit voltage was achieved by variation of the p/i interface treatment but up to now it was accompanied by a decrease of the fill factor. We attribute this effect to a thin undoped amorphous layer at the p/i interface. Under non-optimized deposition conditions an amorphous instead of a microcrystalline silicon layer is grown at the p/i interface which can be detected by Raman measurements on cell structures. While the proper design of the p/i interface is crucial for the cell performance we did not observe significant differences between cells with amorphous and microcrystalline n-layers. The results reveal that the open circuit voltage is limited by the bulk properties of the undoped microcrystalline silicon.


2021 ◽  
Author(s):  
Bablu K. Ghosh ◽  
Ismail Saad ◽  
Khairul A Mahmood

Abstract CdTe thin film (TF) solar cells are most promising in commercial stage photovoltaic (PV) technologies. Cell contacts and interface defects related opto-electrical losses are still vital to limit its further technological benefit. Thin film PV cells voltage and fill factor loss lessening purpose carrier selective back contact selection with band matching interface layers are essential. Beside that buffer and active layer thickness selection is vital for field assisted selective carrier collection. The suitable emitter or buffer layer thickness and band gap matching to the active layer is potential to lessen parasitic absorption and shallow recombination loss. In this purpose SCAPS software based ZnO and SnO2 TCO as well as CdS and CdSe buffer impact are numerically analyzed. The TCO, emitter, back surface field layer and metal contacts effects on electrical performance is studied. In the model, TCO and back contact barrier thickness is shown significant to progress electrical performance. Eventually, open circuit voltage Voc = 0.9757 V and 19.92% efficiency is achieved for 90 nm of ZnTe BSF with ZnO TCO and CdS emitter layer of optimized thickness.


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