Solvent racing crystallization: Low-solvation dispersion cosolvents for high-quality halide perovskites in photovoltaics

The solvation capacity of dispersion solvents plays a crucial role in the solution processing of metal halide perovskites. For instance, N,N-dimethylformamide (DMF), a widely used dispersion solvent, possesses high solvation capacity but often generates suboptimal film quality due to slow crystallization kinetics. We propose using low-solvation binary cosolvents (nitrile- and ether-type solvents) to achieve a balance between solvation (i.e., sufficient solubility of precursors) and desolvation (i.e., rapid crystallization of films) processes during perovskite synthesis. The polarity and hydrogen-bonding property of these cosolvents synergistically enhance their solvation capacity, facilitating perovskite precursor dissolution. Moreover, the low-solvation cosolvents accelerate the crystallization of well-defined intermediate films, yielding higher-quality perovskites than those synthesized with DMF. The optimized modules achieved an active-area efficiency of 22.27%, with a certified aperture-area efficiency of 16.10% and corresponding active-area efficiency of 20.75%. This research on solvation regulation provides universal guidelines for innovatively preparing high-quality halide perovskites.