Highly stable perovskite solar cells in humid and hot environment

An organic-inorganic perovskite solar cell (PSC) is a very promising candidate for a next-generation photovoltaic system. For the last three years, the power conversion efficiency (PCE) of PSCs has been dramatically improved from 9.7% to 22.1%; however, a poor long-term stability still limits the commercialization of PSCs. In this study, we explore the effect of poly(methyl methacrylate) (PMMA)/reduced graphene oxide (rGO) composite (PRC) passivation layer on the chemical and thermal stability of PSCs. The PRC passivation layer shows superior protection performance due to improved hydrophobicity and increased complexity of the O-2 or H2O diffusion pathway. Moreover, the excellent thermal conductivity of rGO facilitates heat dissipation through the PRC layer. When the PRC layer is coated, the aging of PSCs is significantly prevented even under extreme conditions of humidity (>75%) and temperature (similar to 85 degrees C). Consequently, the PCE of PRC-passivated PSCs exhibits a negligible change in air, temperature of 35 degrees C, and humidity of 40% for 1000 h. Our study offers a simple and robust way to fabricate long-term stable and highly efficient PSCs, thus providing a path to PSC commercialization.