Overcoming Solubility Limitations in Inverse Temperature Crystallization for Universal Growth of High‐Quality Perovskite Single Crystals for X‐Ray Detection

Abstract Solubility is a fundamental property that governs the growth of perovskite single crystals (SCs). The inverse temperature crystallization (ITC) method, which relies on reduced solubility at elevated temperatures, is widely adopted for synthesizing high‐quality perovskite SCs to construct high‐performance X‐ray detectors. However, many perovskite precursors lack the property of reduced solubilities at high temperatures, exhibiting significant limitations on solvent selection. Here, a temperature‐regulated organic‐coordination (TROC) mechanism is introduced to overcome the solvent limitation for a wide range of perovskite compositions. By leveraging polyethylene glycol (PEG) as a coordination modulator, a universal solvent system combining PEG and γ‐butyrolactone (GBL) is established for ITC to synthesize perovskite SCs with different compositions. The TROC mechanism operates by dynamically modulating the coordination strength between PEG and perovskites under different temperatures. Specifically, PEG strongly coordinates with Pb 2+ ions by displacing both GBL molecules and halide ions, significantly enhancing perovskite solubilities at low temperatures. As temperatures rise, the coordination strength of PEG significantly declines, causing reductions in solubilities and precipitations of perovskite SCs. The synthesized perovskite SCs exhibit excellent qualities, which promotes the application in X‐ray detection with high performances. This work provides a new mechanism for synthesizing high‐quality perovskite SCs and advances their further applications.