Structural effects of the SnO2 electron transport layer on the reliability of perovskite solar cells

Abstract

The electron transport layer (ETL) in perovskite solar cells (PSCs) acts both as a functional layer and a substrate for perovskite crystallization, which exerts a profound influence on interfacial quality and overall device performance. Although colloidal dispersions of tin oxide (SnO₂) offer facile processing, the complex composition of these dispersions inevitably introduces defects within the ETL. In this work, we explore sputtering as a deposition method for SnO₂ ETLs and systematically investigate the distinct mechanisms governing interfacial dynamics relative to conventional solution-based processes. Complementary characterization experiments were conducted to elucidate the underlying physicochemical origins of these differences. Notably, the optimized sputtered SnO₂-based devices achieved a power conversion efficiency (PCE) of 21.41%, despite the formation of small-grained perovskite films atop sputtered SnO₂. We find that the poor interfacial characteristics of sputtered SnO₂ ETLs compromise the long-term stability of the resultant devices. Thus, substrate modification or sublayer engineering strategies are proposed as promising avenues for further performance optimization of sputtered SnO₂-based PSCs.