HI hydrolysis-derived intermediate as booster for CsPbI3 perovskite: from crystal structure, film fabrication to device performance

Nowadays, inorganic CsPbI3 perovskite solar cells (PSCs) have become one of the most attractive research hotspots in photovoltaic field for its superior chemical stability and excellent photo-electronic properties. Since the first independent report in 2015, the power conversion efficiency (PCE) of CsPbI3 based PSCs has sharply increased from 3.9% to 19.03%. Importantly, during the developing process of CsPbI3 PSCs, HI hydrolysis-derived intermediate plays an important role: from stabilizing the crystal structure, optimizing the fabricated film to boosting the device performance. In this review, the different crystal and electronic structures of CsPbI3 are introduced. We then trace the history and disputes of HI hydrolysis-derived intermediate to make this review more logical. Meanwhile, we highlight the functions of HI hydrolysis-derived intermediate, and systematically summarize the advanced works on CsPbI3 PSCs. Finally, the bottlenecks and prospects are revealed to further increase the CsPbI3 PSCs performance.