Passivating Charged Defects with 1,6-Hexamethylenediamine To Realize Efficient and Stable Tin-Based Perovskite Solar Cells
Ben Ma, Junwen Chen, Minghao Wang, Xin Xu, Jie Qian, Yao Lu, Wenzhu Zhang, Pengfei Xia, Minchao Qin, Wenjing Zhu, Liuquan Zhang, Shufen Chen, Xinhui Lu, Wei Huang
Abstract
An organic cationic salt, hexamethylenediamine diiodide (HDADI), is introduced into formamidinium tin iodide (FASnI3) perovskite solar cells (PSCs) by consideration of amino group passivation of HDA2+ to iodide of SnI64– and assisted links of amino groups at both ends of HDA2+ to the perovskite unit cell to form the Dion–Jacobson (DJ) layered two-dimensional (2D) perovskite. X-ray diffraction and grazing-incidence wide-angle X-ray scattering characteristics exclude the formation of the DJ layered 2D perovskite. A decent power conversion efficiency (PCE) and stability are derived from the high-quality perovskite films with large coverage, high crystallinity, and disappeared pinholes as well as increased radiative recombination and a prolonged carrier lifetime, which are associated with the interaction of NH3+ and SnI64– octahedra via a hydrogen bond. The interaction not only neutralizes charged defects or dangling bonds of perovskites but also forms a shield to retard the oxidation of Sn2+ to Sn4+ and reduce Sn vacancies. Applications of the HDADI-treated FASnI3 films into PSCs acquire a champion PCE of 7.6% and an outstanding long-term stability of over 550 h to retain 80% of the initial efficiency in a glovebox with a N2 environment. This work may guide the design of highly stable and efficient Sn-based PSCs.