All-inorganic CsPbCl 3 perovskite in ultraviolet (UV) detection is drawing increasing interest owing to its UVmatchable optical band gap, ultrahigh UV stability, and superior inherent optoelectronic properties. Almost all of the reported CsPbCl 3 photodetectors employ CsPbCl 3 nano-or microstructures as sensitive components, while CsPbCl 3 polycrystalline filmbased self-powered photodetectors are rarely studied on account of the terrible precursor solubility. Herein, a novel sequential vapordeposition technique is demonstrated to fabricate CsPbCl 3 polycrystalline film for the first time. High-quality CsPbCl 3 films with excellent optical, electronic, and morphological features are obtained. A self-powered photodetector based on the CsPbCl 3 film is constructed without any charge transport layer, showing a high UV detection performance. A thin p-type PbS buffer layer is further introduced to passivate the surface defects of the CsPbCl 3 layer and decrease the interfacial energy barrier by forming a type-II heterojunction, contributing to a faster hole extraction rate and a suppressed dark current level. The best-performing device achieves an ultrafast response time of 1.92 μs, an ultrahigh on/off ratio of 2.22 × 10 5 , and a responsivity of 0.22 A/W upon 375 nm UV illumination at 0 V bias. This comprehensive performance is the best among all of the CsPbCl 3 photodetectors reported to date. The as-prepared photodetectors also present an eminent UV irradiation and long-term durability in ambient air. Furthermore, a largearea and uniform 625-pixel UV image sensor is fabricated and attains a prominent imaging capability. Our work opens a new avenue for the scalable production of CsPbCl 3 -based optoelectronics.

Researchers have focused on perovskite-based ultraviolet photodetectors due to their significance in fundamental scientific and practical applications. However, toxicity and instability hold back their mass production and commercialization. The lead-free Cs 2 AgBiBr 6 double perovskite, promised to be an alternative, is fabricated mostly by spin coating, which restricts the practical application in high-resolution image sensors. Herein, we demonstrate a sequential vacuum evaporation method for the fabrication of the Cs 2 AgBiBr 6 film. A self-powered ultraviolet photodetector based on the evaporated Cs 2 AgBiBr 6 thin film is further constructed without any carrier-transport layers, for the first time. The best-performing device has a high on/off ratio of 6.6 × 10 3 , and its response time is fast, less than 6.13 μs. Moreover, the as-prepared devices exhibit salient stability under harsh operational conditions (continuous illumination, high temperature, and humidity). In addition, the pixelated image sensor containing a 25 × 25 Cs 2 AgBiBr 6 photodetector array achieves a proof-of-concept special pattern recognition. Our work paves the way for new-generation ultraviolet image sensors composed of environmentally friendly and high-performance perovskite photodetector arrays.

Hybrid perovskite photodetectors generally exhibit brilliant performance for photodetecting in the visible spectrum but poor detectability in the solarblind ultraviolet (UV) region. To break through the bottleneck, we demonstrate a novel strategy to broaden the spectral response of perovskite photodetectors to the solar-blind UV region through phosphor encapsulation. The high photoluminescence quantum yield trichromatic phosphor capping layer achieves an extended spectral response to the solar-blind UV region through effectively down-converting the incident UV light into visible light. In addition, an external quantum efficiency of up to 12.13%@265 nm is achieved without bias voltage, while the initial value is near zero. The corresponding spectral responsivity and detectivity are 0.0269 A/W and 7.52 × 10 11 Jones, respectively. Thus, the photodetectors show a high photocurrent and on/off ratio, increasing by roughly 2 orders of magnitude. Moreover, the photodetectors exhibit a large linear dynamic range of 105 dB, fast response times of 50.16/51.99 μs, and excellent stability. The practical applications for flame detection and UV-based communication are further explored. This work provides a new way to achieve UV light detection based on perovskite photodetectors. Perhaps, it may also be a promising alternative for wide-band gap semiconductors to realize the urgent pursuit of UV detection.

Although a variety of MoS 2 -based photodetectors have been reported over the last few years, the controlled fabrication of large-area photodetector array for photoimaging remains a major challenge due to the low yield and poor quality of MoS 2 film. Herein, a high-performance inkjet-printed flexible photodetector array based on stacked MoS 2 nanosheets is demonstrated for the first time. The 2H phase MoS 2 nanosheets is obtained by intercalating quaternary ammonium cation into MoS 2 bulk. The inkjet-printed photodetector achieves excellent performance with a highest responsivity of 552.5 A W À1 , detectivity of 1.19 Â 10 12 Jones, and fast response and recovery time of 23 and 26 ms, respectively, at room temperature. Furthermore, a photodetector array with 85 pixels per inch is successfully constructed, and the letter of "T" is clearly recognized. These results indicate that electrochemical exfoliation coupled with inkjet printing has great prospect for application in high-performance photodetector array. Besides, the electrochemical exfoliation is also successfully applied to obtain the ink of In 2 Se 3 , black phosphorus (BP), and MoTe 2 . It is believed that this work paves the way for various potential printable optoelectronics based on 2D materials.

CsPbCl3 has gained enormous attention since appearing and showed great potential in ultraviolet photodetectors over the past few years. Processing CsPbCl3¬¬ film through traditional solution methods hits a bottleneck due...