Low-temperature SnO2-based electron selective contact for efficient and stable perovskite solar cells

Abstract

We demonstrated SnO₂ films prepared by sinter-less spin-coating processes as an electron selective contact for CH₃NH₃PbI₃-based planar-heterojunction perovskite solar cells (PSCs). A modified sequential deposition method, in which the grain size of PbI₂ precursors was controlled by an equivalent solvent vapor annealing (SVA) process, was used to prepare the perovskite layer on SnO₂. With this SVA process, the remnant PbI₂ nanocrystals can stably occur at the interface of CH₃NH₃PbI₃/SnO₂ to carry out a passivation effect. The photovoltaic performance of SnO₂-based PSCs is dependent on both the SVA time and the thickness of the perovskite layer. The optimized PSC device achieves the best power conversion efficiency of up to 13% under the AM 1.5 simulated sunlight illumination, which is highly durable over 30 days of storage time with exposure to the ambient air environment.