High coordination-solvent bathing for efficient crystallization of MA-free triple halide perovskite solar cells

Many high-performance perovskite solar cells (PSCs) rely heavily on halogenated antisolvent methods, hampering their potential commercialization. In this work, the industry-compatible dimethyl sulfide (DMS) solvent, which coordinates strongly with the metal cation, is used in a bathing approach to investigate the crystallization of triple halide perovskites. The resulting thin films are more uniform exhibiting preferential crystal growth in the (001) direction (perpendicular to the substrate) and large grains of 444 ± 122 nm compared to 421 ± 147 nm for the reference films. Moreover, the electron diffusion length and lifetimes are enhanced from 1 to 3 μm and from 551 to 1050 ns, respectively, compared to the reference film. The champion solar cell based on our approach exhibits a power conversion efficiency (PCE) of 20.6%, comparable to the conventional lab-scale counterpart at 21.4%. Additionally, the long-term stability of our devices shows that 88% (similar to the reference at 93%) of the initial performance is retained after 60 days at room temperature with 60% relative humidity.