Mitigating Defect States of All-Inorganic CsPbI₂Br Perovskite via Multifunctional 2-Amino-5-Nitrothiazole Additive for an Efficient Air-Processed Outdoor/Indoor Photovoltaics

All-inorganic CsPbI2Br mixed halide perovskites show promise as wide-bandgap photoabsorbers in photovoltaics. However, the rapid crystal growth observed in solution-processed CsPbI2Br often leads to morphologies plagued by pinholes and defects, which limit device performance. This study introduces 2-Amino-5-nitrothiazole (ANT), an innovative precursor additive, to enhance film quality. ANT's selective interactions with the perovskite precursor moderate the crystal growth, resulting in a dense, flawless CsPbI2Br film characterized by superior crystallinity and coverage. Furthermore, the -NH2 group in ANT coordinates with Pb octahedra, effectively mitigating charge defects through NH= I/Br bonds. Simultaneously, S= C-N sites interact with uncoordinated Pb2+ ions, reducing defect states and nonradiative recombination. This innovation achieves an impressive device efficiency of 17.13% with a fill factor (FF) of 83.41%, surpassing the control's efficiency of 15.21% (FF of 80.45%). Notably, the champion device maintains an efficiency of 29.47% under indoor light-emitting diode lighting at 1000 lux. Additionally, the optimized perovskite solar cell demonstrates remarkable stability, retaining approximate to 90% of its efficiency for over 720 h at 85 C-degrees in air, even without encapsulation.