α-Fe2O3/SnO2 electron transport bilayer for efficient and stable perovskite solar cells

The hybrid metal halide perovskite solar cells (PSCs) have drawn substantial interest owing to their high absorption coefficient and affordable fabrication techniques. Outstanding photovoltaic efficiency has been attained by PSCs based on the SnO2 electron transport layer (ETL). Nevertheless, there are several issues with the commercial SnO2 ETLs. An efficient approach to overcome the inherent constraints of a single-layer electron transport layer (ETL) in the fabrication of PSC is to develop a bilayer architecture by combining two distinct types of ETLs with complementary advantages. In order to inhibit interfacial recombination, we present an effective interlayer of hematite (alpha-Fe2O3) between SnO2 and the metal electrode in this work. It is possible to successfully reduce the defects of the alpha-Fe2O3 layer alone by using the alpha-Fe2O3/SnO2 electron transport bilayer. With a negligible hysteresis index of 0.03, the optimized alpha-Fe2O3/SnO2 bilayer ETL in PSC demonstrated outstanding power conversion efficiency (PCE) of 18.24%, J(SC) of 21.29 mA.cm(-2), and FF of 75.13%. Additionally, the best device demonstrated exceptional stability, holding onto 91% of the original PCE after 30 days affirming the impeccable insertion of the alpha-Fe2O3/SnO2 bilayer. Improved electron transfer efficiency, reduced interfacial recombination, and smooth surface morphology contributed towards the enhanced photovoltaic performance of the alpha-Fe2O3/SnO2 bilayer ETL-based-PSC. The path toward novel ETLs for the fabrication of effective and photo-stable PSCs is provided in this study.