Crystallization Regulation and Lead Leakage Prevention Simultaneously for High-Performance CsPbI<sub>2</sub>Br Perovskite Solar Cells
Yanqiang Hu, Yifan Zhou, Zhi Wang, Qing‐Lin Chen, Hao Xu, Tongming Sun, Yanfeng Tang
Abstract
All-inorganic CsPbI 2 Br perovskite is striking as a result of the reasonable band gap and thermal stability. However, the notorious air instability, unsatisfactory conversion efficiencies, and toxic water-soluble Pb 2+ ions have greatly limited the further development of CsPbI 2 Br-based devices. Herein, a facile strategy is developed to prepare efficient and air-stable CsPbI 2 Br-based perovskite solar cells (PSCs) with in situ lead leakage protection. With the introduction of 2,2′-dihydroxy-4,4′-dimethoxy-5,5′-disulfobenzophenone disodium salt (BP-9) into the CsPbI 2 Br precursor solution, the crystallization of perovskite can be regulated at a reduced trap density, the uncoordinated Pb 2+ ions and electron-rich defects in the structure can be passivated to suppress non-radiative recombination, and the energy level arrangement can be optimized to improve charge carrier transport. Consequently, the optimized PSC achieved a championship efficiency of 17.11%, accompanied by negligible J – V hysteresis and remarkably improved air stability. More importantly, the strong chelation of BP-9 with water-soluble Pb 2+ ions minimizes the leakage of toxic lead in the perovskite structure.