Optical Losses in Amorphous Silicon Solar Cells due to Back Reflectors

1997 ◽  
Vol 467 ◽  
Author(s):  
B. L. Sopori ◽  
J. Madjdpour ◽  
B. Von Roedern ◽  
W. Chen ◽  
S. S. Hegedus
Keyword(s):  
Solar Cells ◽  
Numerical Model ◽  
Amorphous Silicon ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Silicon Solar Cells ◽  
Optical Losses ◽  
Back Reflectors ◽  
Current Densities ◽  
Initial Results

ABSTRACTWe have used a new numerical model and here present initial results on how texturing and backreflectors affect the maximum achievable short-circuit current densities in amorphous silicon solar cells.

Thermodynamic limits of nanophotonic light trapping in thin film silicon solar cells

2014 ◽  
Vol 92 (7/8) ◽  
pp. 909-912 ◽  
Author(s):  
Brian R. Maynard ◽  
E.A. Schiff
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Light Trapping ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Silicon Solar Cells ◽  
Thin Film Silicon ◽  
Solar Tracking ◽  
Current Densities ◽  
Thermodynamic Limits

We have extended an earlier thermodynamic treatment of light-trapping in lattice-textured solar cells to higher absorptances. This treatment is used to calculate the quantum efficiency spectra and short-circuit current densities JSC for thin-film silicon solar cells with ideal lattice textures. An optimal triangular lattice period of 900 nm yields a calculated JSC that is 2 mA/cm2 larger than for ideal random textures in a 1000 nm thick cell. We compare the calculations to recent experiments with periodically textured cells. While the experimental cells give JSC values that are comparable to the best cells with conventional textures, they do not show the features associated with the prediction of higher JSC. We discuss the role of imperfections in the periodic texturing, and suggest that cells used with solar tracking may realize the predicted JSC improvement.

Photonic Crystal Back Reflectors for Enhanced Absorption in Amorphous Silicon Solar Cells

2010 ◽  
Vol 1245 ◽  
Author(s):  
Benjamin Curtin ◽  
Rana Biswas ◽  
Vikram Dalal
Keyword(s):  
Solar Cells ◽  
Photonic Crystal ◽  
Amorphous Silicon ◽  
Light Absorption ◽  
Short Circuit ◽  
Silicon Solar Cells ◽  
Etch Depth ◽  
Enhanced Absorption ◽  
Back Reflectors ◽  
Back Reflector

AbstractPhotonic crystal back reflectors offer enhanced optical absorption in thin-film solar cells, without undesirable losses. Rigorous simulations of photonic crystal back reflectors predicted maximized light absorption in amorphous silicon solar cells for a pitch of 700-800 nm. Simulations also predict that for typical 250 nm i-layer cells, the periodic photonic crystal back reflector can improve absorption over the ideal randomly roughened back reflector (or the ‘4n2classical limit') at wavelengths near the band edge. The PC back reflector provides even higher enhancement than roughened back reflectors for cells with even thinner i-layers. Using these simulated designs, we fabricated metallic photonic crystal back reflectors with different etch depths and i-layer thicknesses. The photonic crystals had a pitch of 760 nm and triangular lattice symmetry. The average light absorption increased with the PC back reflectors, but the greatest improvement (7-8%) in short circuit current was found for thinner i-layers. We have studied the dependence of cell performance on the etch depth of the photonic crystal. The photonic crystal back reflector strongly diffracts light and increases optical path lengths of solar photons.

High efficiency p+-n-n+ back-surface field silicon solar cells with very large short-circuit current densities

Solar Cells ◽  
1982 ◽  
Vol 7 (3) ◽  
pp. 331-336 ◽  
Author(s):  
J. Nijs ◽  
J. Van Meerbergen ◽  
F. D'Hoore ◽  
R. Mertens ◽  
R. Van Overstraeten
Keyword(s):  
Solar Cells ◽  
High Efficiency ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Silicon Solar Cells ◽  
Back Surface ◽  
Back Surface Field ◽  
Surface Field ◽  
Current Densities

scholarly journals Reflectance Improvement by Thermal Annealing of Sputtered Ag/ZnO Back Reflectors in a-Si:H Thin Film Silicon Solar Cells

2011 ◽  
Vol 1321 ◽  
Author(s):  
Karin Söderström ◽  
Franz-Josef Haug ◽  
Céline Pahud ◽  
Rémi Biron ◽  
Jordi Escarré ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Thermal Annealing ◽  
Short Circuit ◽  
Flexible Substrate ◽  
Short Circuit Current ◽  
Silicon Solar Cells ◽  
Polyethylene Naphthalate ◽  
Thin Film Silicon ◽  
Back Reflectors

ABSTRACTSilver can be used as the back contact and reflector in thin film silicon solar cells. When deposited on textured substrates, silver films often exhibit reduced reflectance due to absorption losses by the excitation of surface plasmon resonances. We show that thermal annealing of the silver back reflector increases its reflectance drastically. The process is performed at low temperature (150°C) to allow the use of plastic sheets such as polyethylene naphthalate and increases the efficiency of single junction amorphous solar cells dramatically. We present the best result obtained on a flexible substrate: a cell with 9.9% initial efficiency and 15.82 mA/cm2 in short circuit current is realized in n-i-p configuration.

Energy Dependence of Defects in a-Si:H Solar Cells During Degradation and Annealing Processes

1997 ◽  
Vol 467 ◽  
Author(s):  
Domenico Caputo ◽  
Francesco Lemmi ◽  
Fabrizio Palma
Keyword(s):  
Solar Cells ◽  
Amorphous Silicon ◽  
Recovery Rate ◽  
Short Circuit ◽  
Forward Bias ◽  
Short Circuit Current ◽  
Silicon Solar Cells ◽  
Capacitance Measurements ◽  
Current Voltage ◽  
Induced Changes

ABSTRACTIn this work we report on the effect of current-induced degradation and annealing on p-i-n amorphous silicon solar cells. Current-voltage curves and capacitance measurements under forward bias have been used to monitor the current-induced changes as a function of time. We found that the recovery rate increases with the annealing current, while the stabilized value of efficiency decreases. Comparison of short circuit current and capacitance evolution suggests that defect kinetics in the electronic gap occurs in a different way during degradation and annealing. This behavior can be modeled assuming a faster annealing of defects closest to the extended band and a slower annealing of mid-gap defects.

A Carrier Lifetime Model for the Optical Degradation of Amorphous Silicon Solar Cells

1985 ◽  
Vol 49 ◽  
Author(s):  
Z E. Smith ◽  
S. Wagner
Keyword(s):  
Solar Cells ◽  
Amorphous Silicon ◽  
Carrier Lifetime ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Silicon Solar Cells ◽  
Carrier Lifetimes ◽  
Bond Density ◽  
Degradation Data

AbstractThe light-induced performance degradation of amorphous silicon solar cells is described well by a model in which the carrier lifetimes are determined by the dangling bond density. The kinetics of the defect generation follow the model in which band-to-band recombination provides the energy for the creation of dangling bonds, which in turn introduce gap states that reduce carrier lifetime. Degradation will be slower in solar cells operating at lower excess carrier concentrations. This is documented with a comparison of degradation data for cells of different i-layer thickness, cells operating at open circuit vs. load, and for single vs. cascade cells. The model also correctly predicts the relation between short circuit current and fill factor degradation. At sufficiently long times, the efficiency will decrease at approximately the same rate for all cell structures and dimensions, with an offset in time between different device types which can be calculated.

Technologies to Reduce Optical Losses of Silicon Solar Cells

2014 ◽  
Vol 953-954 ◽  
pp. 91-94
Author(s):  
Yu Qin Gu ◽  
Chun Rong Xue ◽  
Ming Liang Zheng
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Light Trapping ◽  
Short Circuit ◽  
Surface Texturing ◽  
Short Circuit Current ◽  
Optical Path Length ◽  
Silicon Solar Cells ◽  
Optical Losses ◽  
Top Contact

Optical losses chiefly effect the power from a solar cell by lowering the short-circuit current. There are a number of ways to reduce the optical losses, which includes top contact coverage of the cell surface can be minimized, anti-reflection coatings can be used on the top surface of the cell, reflection can be reduced by surface texturing, and the optical path length in the solar cell may be increased by a combination of surface texturing and light trapping. This work discusses all of the methods to reduce optical losses of silicon solar cells. Surface texturing, either in combination with an anti-reflection coating or by itself, can be used to minimize reflection, but the large reflection loss can be reduced significantly via a suitable anti-reflecting coatings. Significant improvement of the short circuit current after light trapping design was observed. In addition to these methods, top contact design of silicon solar cells is important. The design of the top contact involves the minimization of the finger and busbar resistance, and the overall reduction of losses associated with the top contact.

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