Design and optimization of nanostructure antireflection film for thin GaAs solar cells based on the photoelectrical coupling model

Anti-reflection film (ARF) with nanostructure plays an important role in reducing surface reflectance and improving power generation performance of solar cells. However, the reduction of reflectance is over-concerned during the design process of ARF, while the actual electrical performance of solar cells caused by structure changes of ARF tends to be ignored. In present study, a two-dimension photo-electric coupling model of thin GaAs cell with moth-eye nanostructured ARF was established, and its optical and electrical performance were investigated. Firstly, the optical and electrical performance of GaAs cells with and without ARF were compared to illustrate the importance of ARF for GaAs cell. Then, the effects of nanostructure parameters of ARF on optical and electrical performance were investigated, and a significant variation of the maximum efficiency (Δηmax = 1.35%) was observed. After that, the energy transmission process of two randomly sampled cases were comparatively analyzed to demonstrate that only taking the reflectance as evaluation index during the design process of ARF is unreasonable. The maximum electrical power output (Pmax) or efficiency (ηmax) was recommended as the appropriate evaluation index. Finally, based on the proposed evaluation index, a multi-parameters optimization was performed for moth-eye structure ARF, and the optimal case was derived with h = 100 nm, W = 100 nm, f = 0.453 and d = 50 nm. The corresponding maximum efficiency is 25.31%, which is 4.82% higher than that of GaAs cell without ARF, and is even 0.22% higher than the maximum ηmax in samples.