Controlling the Formation Process of Methylammonium‐Free Halide Perovskite Films for a Homogeneous Incorporation of Alkali Metal Cations Beneficial to Solar Cell Performance

• DOI: 10.1002/aenm.202103618
• Publication Date: 2022-02-16T04:22:24Z
• Authors: Daming Zheng; Tao Zhu; Yanfa Yan; Thierry Pauporté
• Keywords: Formamidinium; Triiodide; Perovskite solar cell

Abstract Incorporating multiple cations of the 1A alkali metal column periodic table (K + /Rb /Cs ) to prepare perovskite films is promising for boosting photovoltaic properties but requires a uniform distribution. The effects NH 4 Cl additives and on one‐step formation process methylammonium‐free, formamidinium‐based, iodide are analyzed in step‐by‐step manner. improves solubility PbI 2 solution by forming an intermediate then favors phase formation. Moreover, during annealing process, this additive shown increase grain size, improve crystallinity suppress K at low concentration always homogeneously distributed across film thickness. On other hand, Cs more concentrated surface Rb depths pristine films. With additives, these two metals because slows down movement , it changes growth direction film, making overall crystallization quality improved distribution uniform. It results with large monolithic grains. Combined treatment n‐propylammonium iodide, high stabilized power conversion efficiency 22.04% reached.