13.7 % Efficient Graphene/Si Heterojunction Solar Cells with One‐Step Transferred Polymer Anti‐Reflection Layer for Enhanced Light Absorption and Device Durability

Graphene/Silicon (Gr/Si) heterojunction shows great potential as high-efficiency, cost-effective solar cells compared to traditional Si solar cells. However, the high optical loss of c-Si, mainly originating from abrupt change of refractive index at air/Si interface, and the unsatisfactory conductivity of practically prepared graphene layer, still hinder their extensive applications. Herein, we report the performance improved Gr/Si solar cells by depositing a polymathic methacrylate (PMMA) anti-reflection coating (ARC) layer through a one-step transferred method. The graphene and PMMA ARC with specific thickness were transferred on n-type Si wafer at the same time, which reduces production steps and obtains high-quality graphene layer. By tuning the thickness of the PMMA layer, the reflection can be reduced obviously. Companying with the HNO₃ vapor doping for graphene, the Gr/Si heterojunction solar cell with a high power conversion efficiency (PCE) of 13.7 % was achieved. In addition, the durability of the device is improved under HNO₃ doping. Considering the easy and cost-effective solution processed capability of the one-step transferred graphene and PMMA ARC layer, we believed that PMMA/Gr/Si is a feasible low-temperature technique for high-efficiency Si solar cells.