Nonideal Effects Limit the Efficiency Gain for Angle-Restricted Solar Cells

Journal Article · 27 October 2015 · IEEE Journal of Photovoltaics

DOI: https://doi.org/10.1109/JPHOTOV.2015.2480227 · OSTI ID:1579862

Khan, M. Ryyan ^[1]; Wang, Xufeng ^[2]; Alam, Muhammad A. ^[2]

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1. Purdue Univ., West Lafayette, IN (United States); Purdue university
2. Purdue Univ., West Lafayette, IN (United States)

We report that performance of a conventional solar cell at 1 sun is limited to ~31%, defined by the Shockley–Queisser (SQ) limit. The thermodynamic limit can be improved to ~41% by reducing the angle mismatch between incident light and emitted rays. This can be achieved either by increasing the range of incident angles (as in a concentrator cell; CPV) or by reducing the emission angle from the device (angle-restricted photovoltaics; APVs). The equivalence is exact in the radiative limit. However, the gains of angle-restricted cells may erode rapidly once nonradiative recombination and other optical losses are accounted for, suggesting the need for quantitative/careful design. Here, we report a detailed self-consistent absorption-emission-transport study to 1) define the limiting efficiency of APV scheme and 2) explain the efficiency loss due to practical constraints, such as Shockley–Read–Hall (SRH) and Auger recombination, and mirror reflectivity. Our analysis reflects a growing consensus in the field that any imperfection of the mirror quickly diminishes the advantages of angle restriction. Finally, we conclude that a 50-nm angle-restricted cell with moderate material quality, but with nearly perfect mirror and Lambertian trapping, may be ~36–37% efficient.

• Research Organization: Stanford Univ., CA (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: AC36-08GO28308; EE0004946
• OSTI ID: 1579862
• Journal Information: IEEE Journal of Photovoltaics, Journal Name: IEEE Journal of Photovoltaics Journal Issue: 1 Vol. 6; ISSN 2156-3381
• Publisher: IEEECopyright Statement
• Country of Publication: United States
• Language: English