Single‐step post‐production treatment of lead acetate precursor‐based perovskite using alkylamine salts for reduced grain‐boundary related film defects

Powered by the worldwide efforts of research groups experienced in dye-sensitized, and thin-film solar cells, perovskite solar cells (PSCs) reached a power conversion efficiency of 25.7% within 10 years. However, the presence of defects and trap density within the active layer’s grain boundaries commonly operates as non-radiative recombination centers. Hence, intensive efforts have been reported to passivate the inevitable bulk and interface defects of the active layer using additives or post-treatment processing to enhance the efficiency and stability of PSCs. Herein, a facile post-treatment strategy based on wet processing methylammonium lead triiodide, MAPbI 3 (prepared from lead acetate and methylammonium iodide precursors) films with organic amine salts (FABr and FAI) is demonstrated. As a result, high-quality films of mixed per-ovskites (FA x MA 1-x PbI 3-x Br x and FA x MA 1-x PbI 3 ) were obtained. The surface treatment has efficiently passivate the defects in the host film, suppressing the non-radiative carrier recombination. Compared to the control device, the increased open-circuit voltage (from 0.5 V to 1 V) and fill factor (FF) values of the optimized device based on FA x MA 1-x PbI 3 showed a PCE of 16.13%. And our findings revealed that post-treatment is possible on wet perovskite film aged for a few minutes prior to its post-treatment, which saved the energy used for pre-annealing.