Endogenous Intermediate Template Guided Crystallization for High Performance FAPbCl₃ UV Detector

Lead-chloride perovskite is a promising candidate for the active layer of UV detectors. However, due to the high ionic character of chloride compound, it is difficult to form a ligand-lead adduct that guides the crystallization of perovskite, resulting in poor film quality and device performance. Herein, an endogenous intermediate template strategy is developed to guide the crystallization of lead-chloride perovskite FAPbCl₃ (FA = formamidine). Based on the enrichment of hydrogen bonds between ligands, a low dimensional N-Pb-O adduct FAPbCl₃-DMSO (DMSO = dimethyl sulfoxide) is observed in precursor liquid. This results in the endogenous formation, not the external introduction of low dimensional FA_xPbCl_y (x>1, y>3) intermediate phase, serving as a crystallization template guiding the oriented growth of FAPbCl₃ perovskite film with large and closely packed grain. As a result, the film shows much stronger PL intensity and significantly reduced defect density. Therefore, a self-driven lead-chloride perovskite UV detector is realized with responsivity, detectivity and response time of 0.63 A W^-1, 1.3 × 10¹³ Jones, and 205/53 µs at 365 nm and zero bias. Furthermore, for the first time, a uniform 64 × 64 lead-chloride perovskite UV array detector is successfully fabricated and achieves a promising image sensing function.