Ultrafast Response (

Abstract Benefiting from the rapid development on chloride incorporated perovskite materials, nowadays, novel device fabricating techniques have sparked a new vision of ultraviolet photodetectors (UVPDs), which is moving toward higher precision, lower energy consumption, and greater miniaturization. Nevertheless, the natural poor solubility of chloride precursors for perovskites has limited their processability for achieving high‐performance self‐driven photovoltaic‐type UVPDs. Herein, a ball‐milling pretreated single‐source vapor deposition strategy is presented, which can facilely fabricate a pure‐phase CsPbCl3 perovskite film with supermicrometer crystal size and no grain boundaries in the vertical direction. Based on this excellent quality UV harvesting perovskite layer, an optimized self‐driven visible‐blind UVPD exhibits outstanding detection properties, including a superior peak responsivity of 118 mA W−1, a maximum specific detectivity of 6.62 × 1012 Jones, and a wide linear dynamic range of 136 dB, coupled with >1000 h operational durability in air ambient. Most notably, a recorded ultrafast rise/fall response time of 120/820 ns is realized as the fastest responsive perovskite UVPDs to date. In addition, this CsPbCl3 UVPD offers adequate visible‐transparency (>50% average visible transmittance) for a glazing integration by using a transparent back electrode, providing a promising pathway to realize a transparent sensor system for future smart window applications.