Enhanced Stability and Bendability of Perovskite Solar Cells by Dual Interlayer Passivation

Abstract Engineering at interface between perovskite and charge transport layers is crucial for improving operational stability. In inverted perovskite solar cells (PSCs) with a core configuration of HTL/perovskite/ETL/HBL (HTL = hole transporting layer; ETL = electron transporting layer; HBL = hole blocking layer), the interfaces at ETL based on phenyl‐C 61 ‐butyric acid methyl ester (PCBM) are more defective due to its molecular geometry, leading to imperfect adhesion. We introduce the dual interlayer passivation at perovskite/PCBM and PCBM/HBL to enhance the adhesion and passivate interlayers. Materials for engineering the dual interfaces require different functional groups, where carbamylcholine chloride at the perovskite/PCBM interface results in a more compact PCBM layer, while γ‐butyrobetaine hydrochloride is suitable for passivating the interface between PCBM and HBL, leading to reduction in charge accumulation and improving electron transport. The dual interlayer passivation minimizes the device degradation induced by continuous light exposure and mechanical stress. As a consequence, the target device retains over 80% of its initial performance after 500 hours of maximum power point tracking (MPPT) under one sun illumination, and over 95% after 10 000 bending cycles at 5 mm radius. Both conditions exhibit more than 7‐fold enhancement in light‐soaking and bending stability than the unpassivated control devices.