Heterogeneous electron transporting layer for reproducible, efficient and stable planar perovskite solar cells

Organometal-halide perovskites continue to attract a large number of solar enthusiasts due to their intrinsic properties as promising solar absorbers with relatively low processing cost. However, commercialization of perovskite solar cells remains distant, especially in the planar perovskite configuration, because of various problems such as inconsistency, poor environmental stability, and small-scale production. In this study, we present the use of complimentary electron transporting layers (ETLs) as a highly effective approach to cover the weaknesses of individual ETLs while boosting the strengths of various ETL compositions. Heterogeneous AITO/SnO₂ ETL based device demonstrates paramount efficiency of 18.90% and exhibits superior stability maintaining 93% of its initial efficiency after 25 days in the absence of encapsulation at relative humidity of 30–40%. Furthermore, the simple addition of a consistent AITO layer allows improvement in reproducibility, while the simple addition of a SnO₂ layer exhibits significant enhancement in electron mobility and reduction in recombination sites at the AITO/perovskite interface. In essence, our results suggest the use of compatible heterogeneous ETLs as an appealing method to provide synergistic enhancements in various photovoltaic parameters, device stability, and also device reproducibility of planar perovskite devices.