Buried interface management for FAPbI₃-based perovskite solar cells via multifunctional benzothiadiazole derivatives

Attaining high efficiency in perovskite solar cells (PSCs) often necessitates effective interfacial passivation, which poses challenges, especially concerning the buried interface due to the dissolution of passivation agents during perovskite deposition. In this work, we report a multifunctional modification strategy by introducing the variations of benzothiadiazole (BTD) derivatives to function as interface-modified layers in PSCs. This buried interface modification mitigates oxygen vacancies on the SnO₂ surface and fine-tunes the energy level of the electron transport layer, resulting in an improved alignment with the FAPbI₃ layer. Furthermore, the introduced BTD derivatives led to the improved crystallinity of FAPbI₃ films as well as suppressed the non-radiative recombination losses through passivating the interfacial defects. Consequently, a device with modified SnO₂ exhibited an enhanced power conversion efficiency (PCE) of 25.04% along with an improved long-term device stability.