Abstract Ultraviolet band C photodetectors (UVC PDs), which can convert the UVC light (200–280 nm) signals into detectable signals, have received tremendous attention due to their wide applications in bio‐medicine, communications, and imaging fields. However, current research primarily focuses on either the conversion of UVC light into electrical signals or its conversion into visible light signals. Here, a flexible dual‐detectable UVC PD based on Ca 2 Nb 3 O 10 nanosheets and CsCu 2 I 3 film is reported, which can simultaneously convert UVC light into visible light and electrical signals, achieving the visual detection for invisible UVC light. The PD exhibits exceptional self‐powered UVC light (270 nm; 1.87 mW cm −2 ) detection abilities with a high responsivity (R) of 16.7 mA W −1 , an impressive detectivity of 6.1 × 10 11 Jones, a high on/off ratio of 3789, and an ultra‐high UVC/UVA (R 270 /R 360 ) rejection ratio of 2.1 × 10 5 . The dual‐detectable PD shows great application potential for safety communication and real‐time imaging. This work proposes a new type of flexible PD through material selection and structural design, thereby inspiring novel ideas to enhance the convenience and practicality of UVC photodetection.
