Synchronous Regulation Strategy of Pyrrolidinium Thiocyanate Enables Efficient Perovskite Solar Cells and Self‐Powered Photodetectors

Abstract Developing inventive approaches to control crystallization and suppress trap defects in perovskite films is crucial for achieving efficient perovskite photovoltaics. Here, a synchronous regulation strategy is developed that involves the infusion of a zwitterionic ionic liquid additive, pyrrolidinium thiocyanate (PySCN), into the perovskite precursor to optimize the subsequent crystallization and defects. PySCN modification not only orchestrates the crystallization process but also deftly addresses trap defects in perovskite films. Within this, SCN − compensates for positively charged defects, while Py + plays the role of passivating negatively charged defects. Based on the vacuum flash evaporation without anti‐solvent, the air‐processed perovskite solar cells (PSCs) with PySCN modification can achieve an extraordinary champion efficiency of 22.46% (0.1 cm 2 ) and 21.15% (1.0 cm 2 ) with exceptional stability surpassing 1200 h. Further, the self‐powered photodetector goes above and beyond, showcasing an ultra‐low dark current of 2.13 × 10 −10 A·cm −2 , a specific detection rate of 6.12 × 10 13 Jones, and an expansive linear dynamic range reaching an astonishing 122.49 dB. PySCN modification not only signifies high efficiency but also ushers in a new era for crystallization regulation, promising a transformative impact on the optoelectronic performance of perovskite‐based devices.