Room‐Temperature Solvent Evaporation Induced Crystallization: A General Strategy for Growth of Halide Perovskite Single Crystals by Applying the Le Chatelier's Principle

The growth of high‐quality halide perovskite single crystals is imperative to study their intrinsic physical properties and to realize high‐performance optoelectronic devices. Here, a room‐temperature solvent evaporation‐induced crystallization (RTSEIC) method is reported based on Le Chatelier's principle, which provides a general strategy to grow halide perovskite single crystals including 3D, 2D, 1D, and 0D, and either hybrid or all‐inorganic halide perovskites. Taking 2D n‐BA2PbBr4 (n‐BA = butylammonium) as an example, the room‐temperature crystallization kinetics is demonstrated. The centimeter‐sized n‐BA2PbBr4 single crystals exhibit an extremely small full width at half maximum (FWHM) of 0.024° in (0 0 2) plane rocking curve and a small trap density of 2.74 × 1010 cm−3. The superior crystalline quality endows the n‐BA2PbBr4 single crystal ultraviolet photodetectors with recorded performance among reported n‐BA2PbBr4 ultraviolet photodetectors, demonstrating a detectivity reaching 1.8 × 1013 Jones, a fast response time of 55 µs and a high on‐off ratio of 104. The low‐cost, simple, general, and efficient RTSEIC method is anticipated to promote the blossoming of halide perovskites single crystals. Perovskite single crystals with different dimensions and compositions are grown by the room‐temperature solvent evaporation‐induced crystallization method. The fast reaction between evaporated acid solvent and solid KOH breaks the evaporation‐condensation balance and leads to a lower real pressure than the saturated value. Continue solvent evaporation driven by the pressure difference induces solution concentration increase and crystallization.