Regulating the microscopic structure of solutions to synthesize centimeter-sized low-dimensional Cs m Sb n Cl m +3 n perovskite single crystals for visible-blind ultraviolet photodetectors

Chlorine-based all-inorganic lead-free halide perovskites exhibit excellent properties in visible-blind ultraviolet detectors. However, the quality and size of these solution-grown single crystals are still far from meeting commercial standards due to their low solubility, and a fundamental understanding of the underlying causes of low solubility is still lacking. Herein, the effects of the microscopic structure of solutions on the solubility have been systematically investigated, and it has been demonstrated that a hybrid solvent consisting of dimethyl sulfoxide and hydrochloric acid can significantly improve the solubility of the raw materials of Cs m Sb n Cl m +3 n (SbCl 3 and CsCl). Centimeter-sized high-quality α-Cs 3 Sb 2 Cl 9 and Cs 5 Sb 2 Cl 11 single crystals are grown by the effective hybrid solvent. The low dark current density (91 pA cm −2 ), excellent wavelength selectivity ( R 360 / R 480 = 150), and fast response speed ( t r = 21.7 ms, t d = 104.4 ms) of the photodetector based on the Au/α-Cs 3 Sb 2 Cl 9 /Au structure powerfully demonstrate the great potential of Cs m Sb n Cl m +3 n in ultraviolet applications. Furthermore, the method of using hybrid solvents to increase solubility can be extended to the growth of all inorganic chloride perovskite single crystals, thereby driving the exploration of their future optoelectronic applications.