High‐Quality Perovskite Single Crystal Fabrication via Self‐Assembled Microvesicles Assisted Localized Precursor Release

The supersaturation degree of perovskite precursors is hardly controllable, usually leading to explosive nucleation, which is a great challenge for the solution growth of large-scale single crystals. In this work, a straightforward strategy is developed to simultaneously achieve precise nucleation control and significant growth acceleration of diverse perovskite single crystals through self-assembled propyl methacrylate-polyhedral oligomeric silsesquioxane (PMA-POSS) microvesicles. The microvesicles encapsulate high concentrations of perovskite precursors and achieve localized release via thermal polymerization-induced rupture. As the precursor concentration locally surges in the micro-region, the nucleation number is conspicuously suppressed and the crystal growth rate is expedited almost threefold. More importantly, the as-fabricated MAPbI₃ single crystal possesses superior crystal quality in comparison with the routinely grown counterpart, which demonstrates a remarkably low trap density of 8.76 × 10⁸ cm^-3 and an impressive X-ray response sensitivity of 2.67 × 10⁵ µC Gy_air ^-1 cm^-2. This work provides an effective and universal methodology for high-quality perovskite single crystal fabrication.