Stable and efficient air-processed perovskite solar cells employing low-temperature processed compact In2O3 thin films as electron transport materials

Perovskite solar cells (PSCs) have achieved remarkable power conversion efficiencies (PCEs) owing to their extraordinary optoelectronic properties. Electron transporting layer (ETL) has been proved to have a significant influence on the photovoltaic performance and stability of cell devices. Herein, for the first time, we prepare a low-temperature processed compact In2O3 film derived from a highly stable modified indium precursor solution as a promising ETL for stable and efficient air-processed PSCs. The addition of acetylacetone as a chelation ligand in the solution effectively inhibits the hydrolysis reactions by chelating In3+, thus contributing to the formation of compact In2O3 film at a low temperature of 200 °C. Dense CH3NH3PbI3 perovskite films with many microns-scale grains are fabricated using a scalable doctor-blade method under a harsh ambient condition (relative humidity of 40–50%). Using the proposed compact In2O3 film as ETL, the electron extraction and charge transport at the ETL/perovskite interface are significantly improved. As a result, the air-processed PSC based on compact In2O3 film delivers a champion PCE of 13.97%, greatly outperforming the device with a pristine In2O3 film (9.81%). In addition to high efficiency, the PSC incorporating proposed compact In2O3 film exhibits an excellent long-term stability, maintaining 94% of its initial PCE after stored in air for 31 days. This study demonstrates the feasibility of fabricating stable and efficient air-processed PSCs using low-temperature processed In2O3 ETL, which is expected to have a positive impact in the manufacturing community of solution-processed In2O3 film as well as air-processed PSCs.