Research on Double-layer Anti-reflection Structures of Silicon Heterojunction Solar Cells with 95% High Bifaciality

In this paper, the photogenerated current density and absorbance of silicon heterojunction（SHJ） solar cells with different wafer thickness from 50 μm to 200 μm were simulated by PV Lighthouse. It is found that the limitation of photogenerated current of flexible SHJ solar cells is caused by decreased substrate absorbance. Thus, the anti-reflection（AR） structures including TCO/MgF₂ and TCO/SiO₂ with different film thickness were simulated to obtain the best photogenerated current density. In experimental methods, MgF₂ thin film was prepared by thermal evaporation and SiO₂ thin film was deposited by RF magnetron sputtering. The MgF₂/SiO₂ AR structure with high transmittance（92.56%） was fabricated, which can reduce the reflectance of the SHJ substrate from 6.70% to 5.46%. In addition, the MgF₂/SiO₂ AR structure was applied on the rear side of SHJ solar cell and single MgF₂ or SiO₂ film for front side. The short circuit current density(J_SC) when illumination from rear side improved obviously above 1.10 mA/cm² due to the rear EQE was significantly increased by 2.35%. Moreover, the bifaciality of SHJ solar cell has been achieved 95.16% in this work, which is of great importance to enhance power generation of glass-glass photovoltaic modules.