Large‐Scale, Uniform‐Patterned CsCu 2 I 3 Films for Flexible Solar‐Blind Photodetectors Array with Ultraweak Light Sensing

Abstract Cesium copper halide perovskite is one of the promising materials for solar‐blind light detection. However, most of the cesium copper halide perovskite‐based photodetectors (PDs) are focused on ultraviolet A detection and realized on the rigid substrate in the single device configuration. Here, a flexible solar‐blind PDs array (10 × 10 pixels) based on the CsCu 2 I 3 film patterns for ultraweak light sensing and light distribution imaging is reported. Large‐scale CsCu 2 I 3 film arrays are synthesized with various shapes and uniform dimensions through a simple vacuum‐heating‐assisted solution method. Benefiting from excellent air stability and superior resistance to the photodegrading of the CsCu 2 I 3 film, the array device exhibits long‐term stable photoswitching behavior for 8 h and ultralow light detection capability to resolve the light intensity of 6.1 nW cm −2 with a high responsivity of 62 A W −1 , and the array device can acquire clear images of “G”, “X”, and “U” showing the input light distribution. Moreover, the flame detection and warning system based on a curved solar‐blind PDs array is demonstrated, which can be used for multi‐flame monitoring and locating. These results can encourage potential applications of the CsCu 2 I 3 film‐based PDs array in the field of optical communication and environment monitoring.