Poly(vinylpyrrolidone)-doped SnO2 as an electron transport layer for perovskite solar cells with improved performance

Abstract

Thin film tin oxide (SnO₂) is a good electron transport layer (ETL) for perovskite solar cells (PVSCs) with its excellent optical and electrical properties as well as facile accessibility. However, for high-performance PVSCs, the electron mobility of SnO₂ should be further improved by optimizing its film quality. Herein, we report a poly(vinylpyrrolidone) (PVP)-doped SnO₂ (P-SnO₂) as an ETL for PVSCs with increased efficiencies and improved stability. The P-SnO₂ film exhibits improved electron transport over the control SnO₂. At the same time, the perovskite grown on P-SnO₂ shows more uniform crystalline grains, higher electron mobility and lower defect density than the control sample grown on the pure SnO₂. Moreover, P-SnO₂ can efficiently extract electrons from the perovskite layer with its optimal conduction band. Therefore, the optimized device based on P-SnO₂ shows an improved power conversion efficiency (PCE) of 19.42% compared with the control PVSC based on SnO₂, which exhibits a PCE of 18.05%. Furthermore, the P-SnO₂-based devices show reduced hysteresis and better stability without any encapsulation. Our results provide a facile strategy to fabricate PVSCs with improved performance by incorporating a small amount of PVP into the SnO₂ ETL.