Interface Engineering of High-Performance Perovskite Photodetectors Based on PVP/SnO₂ Electron Transport Layer

Hybrid organic-inorganic perovskites have attracted intensive interest as active materials for high-performance photodetectors. However, studies on the electron transport layer (ETL) and its influence on the response time of photodetectors remain limited. Herein, we compare the performances of perovskite photodetectors with TiO₂ and SnO₂ ETLs, especially on the response time. Both photodetectors exhibit a high on/off current ratio of 10⁵, a large detectivity around 10¹² Jones, and a linear dynamic range over 80 dB. The SnO₂-based perovskite photodiodes show ultrahigh response rates of 3 and 6 μs for the rise and decay times, respectively. However, photodetectors with TiO₂ ETLs have low responsivity and long response time at low driving voltage, which is attributed to the electron extraction barrier at the TiO₂/perovskite interface and the charge traps in the TiO₂ layer. Furthermore, the dark current of SnO₂-based perovskite photodiodes is effectively suppressed by inserting a poly(vinylpyrrolidone) interlayer, and then the on/off current ratio increases to 1.2 × 10⁶, corresponding to an improvement of 1 order of magnitude. Such low-cost, solution-processable perovskite photodetectors with high performance show promising potential for future optoelectronic applications.