Enhanced Performance and Stability of Perovskite Solar Cells Through Modification of SnO₂ Electron Transport Layer with Stable Conformation Surfactant

Uncontrolled deposition of tin oxide (SnO₂) colloidal nanoparticles and perovskite precursors poses challenges for improving the efficiency and stability of perovskite solar cells (PSCs). Modifying the electron transport layer (ETL) can both enhance its own performance and influence the crystallization kinetics of the upper perovskite layer. This study incorporates chain-like surfactants with spatially opposite charges for ETL modification. It is found that molecular conformational changes induced by the flexibility of the carbon chain lead to the collapse of the urchin-like structure, impacting the passivation effect and SnO₂ deposition. Due to the more stable conformation of short-chain surfactant, the fully extended carbon chains in the SnO₂ micelles form a stable urchin-like structure, establishing a stronger aggregation barrier that ensures uniform deposition. The ordered distribution of molecules in the ETL allows functional groups to be fully exposed on the ETL surface and facilitates interlayer modification. This approach enhances passivation across layers, alleviates interfacial tensile stress, promotes interlayer contact, and extends the processing window of perovskite, thereby ensuring the high-performance PSCs. Ultimately, an optimized ETL substrate strategy increases PSC device efficiency from 22.21% to 24.12%, and greatly improves the stability of the unencapsulated device under various conditions, providing a new option for ETL modification engineering.