Solution‐Processed Visible‐Blind Ultraviolet Photodetectors with Nanosecond Response Time and High Detectivity

Abstract Ultrafast, high‐sensitivity, visible‐blind ultraviolet (UV) photodetectors are crucial for practical applications, including: optical communication, environmental ozone hole monitoring, and combustion and chemical detection. However, commercial visible‐blind UV photodetectors based on traditional inorganic semiconductor materials involve expensive production processes, while the currently solution‐processed detectors still suffer from issues of low sensitivity or slow response speed. Herein, high‐performance visible‐blind UV photodetectors with simultaneously ultrafast response speed and high detectivity are achieved from solution‐processed micrometer‐thick methylammonium lead trichloride perovskite thin single crystals, grown in high quality with smooth surfaces by judiciously designing the substrate's wettability. The as‐fabricated UV photodetectors exhibit a low noise of 6.5 fA Hz^−1/2, a low detection limit of 8.5 pW cm⁻², and high specific detectivity of ≈6 × 10¹² Jones. A fast response time of 15 ns and a large bandwidth of 25 MHz are obtained when decreasing the crystal thickness to 1 µm. The nanosecond response speed is several orders of magnitude faster than the best ever reported solution‐processed visible‐blind UV photodetectors and is comparable to reported UV photodetectors based on traditional (high‐temperature processed) inorganic semiconductors. The high performance combined with low‐cost fabrication makes these visible‐blind UV photodetectors highly attractive for applications in optical communication and ultrafast detection.