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

Abstract 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, MAPbI3 (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 perovskites (FAxMA1‐xPbI3‐xBrx and FAxMA1‐xPbI3) 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 FAxMA1‐xPbI3 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.