TY - GEN
T1 - Broadband absorption enhancement in thin film solar cells using inverse optimization of light trapping mechanisms
AU - Hajimirza, Shima
AU - Heltzel, Alex
AU - Howell, John
PY - 2012
Y1 - 2012
N2 - In this paper, global optimization techniques are used to design broadband solar absorption enhancement in thin film amorphous silicon (a-Si) solar cells, using periodic nanostructures on the top and bottom surfaces of the cell. Considering a combination of silver rectangular gratings and indium tin oxide (ITO) coatings on both surfaces of the a-Si, numerical optimization techniques such as Simulated Annealing and a local constrained Quasi-Newton algorithm are used to optimize the surface texture patterns. Numerical results indicate that, unlike the case of metallic gratings on the front surface, a periodic silver grating structure on the back surface results in a modification of the absorption spectrum largely independent of the effect of anti-reflection ITO coatings on the front of the cell. Furthermore, additional improvement can be obtained by using a thin rear surface ITO layers. Therefore, using a combination of metallic gratings and ITO coatings on both sides, a wideband absorption spectrum enhancement is achievable. Simulations predict integrated enhancement factors as high as 2.0 (100% improvement) for the case of metallic grating on the back surface and ITO layers on the front, and as high as 2.2 (120% improvement) when a combination of grating and ITO coatings on both sides is used. Such noteworthy improvements are made possible by efficient multi-parameter optimization supplanting an intractable exhaustive search.
AB - In this paper, global optimization techniques are used to design broadband solar absorption enhancement in thin film amorphous silicon (a-Si) solar cells, using periodic nanostructures on the top and bottom surfaces of the cell. Considering a combination of silver rectangular gratings and indium tin oxide (ITO) coatings on both surfaces of the a-Si, numerical optimization techniques such as Simulated Annealing and a local constrained Quasi-Newton algorithm are used to optimize the surface texture patterns. Numerical results indicate that, unlike the case of metallic gratings on the front surface, a periodic silver grating structure on the back surface results in a modification of the absorption spectrum largely independent of the effect of anti-reflection ITO coatings on the front of the cell. Furthermore, additional improvement can be obtained by using a thin rear surface ITO layers. Therefore, using a combination of metallic gratings and ITO coatings on both sides, a wideband absorption spectrum enhancement is achievable. Simulations predict integrated enhancement factors as high as 2.0 (100% improvement) for the case of metallic grating on the back surface and ITO layers on the front, and as high as 2.2 (120% improvement) when a combination of grating and ITO coatings on both sides is used. Such noteworthy improvements are made possible by efficient multi-parameter optimization supplanting an intractable exhaustive search.
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U2 - 10.1115/MNHMT2012-75065
DO - 10.1115/MNHMT2012-75065
M3 - Conference contribution
AN - SCOPUS:84882445934
SN - 9780791854778
T3 - ASME 2012 3rd International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2012
SP - 559
EP - 567
BT - ASME 2012 3rd International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2012
T2 - ASME 2012 3rd International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2012
Y2 - 3 March 2012 through 6 March 2012
ER -