Improving Photovoltaic Performance of Pb‐Less Halide Perovskite Solar Cells by Incorporating Bulky Phenylethylammonium Cations

Alloyed tin–lead (Sn–Pb) perovskite solar cells (PSCs) exhibit a broader photoresponse up to 1050 nm; however, their efficiency is inferior to that of Pb analogs. Trap‐assisted recombination associated with Sn vacancies formed through Sn2+ oxidation is a major detrimental factor, limiting their efficiency. By incorporating bulkier phenylethylammonium (PEA) cations into Sn–Pb alloyed perovskites, the nonradiative recombination by lowering the number of defects associated with Sn vacancies is reduced. Herein, the effects of PEA cations in different Sn–Pb halide perovskite compositions with a series of characterizations, such as photoluminescence, X‐ray photoelectron spectroscopy, and surface potential measurements, are investigated. As a result of the reduction of traps in PEA‐containing perovskites, a significant improvement of 40% and 15% in photovoltaic performance is observed for Sn‐rich and Pb‐rich Sn–Pb halide perovskites, respectively. Herein, various Sn–Pb halide perovskite compositions with different bandgaps have been realized by mixing FASnI3 and MAPbI3 at different ratios. Incorporation of an optimized amount of bulky aromatic cations in these Sn–Pb halide perovskites has been shown to improve the efficiency and stability of perovskite solar cells due to the passivation of defects associated with Sn oxidation.