Self-powered and broadband CuSCN/Si heterojunction photodetector for multi-color imaging based on diffuse reflection mode.

Copper thiocyanate (CuSCN) has been widely used in photodetectors (PDs). However, the reported CuSCN-based PDs are suffered from narrow operating wavelength range and relatively low photodetection performance. Here, we fabricate an CuSCN/Si heterojunction PD by a simple low-temperature solution spin-coating method achieving excellent performance. Our designed CuSCN/Si PD exhibits a broadband response range covering ultraviolet-visible-infrared, a high detectivity of 2.26×1012 Jones coming from an ultralow dark current of 23 pA, and a decent responsivity of 11 mA/W, a high linear dynamic range of 122 dB, and short response time of 25/150 μs (rise and decay time). Moreover, we demonstrate multi-color imaging across the wide wavelength range, indicating the CuSCN/Si PD has a promising potential in the imaging field. This work may pave the way for fabricating low-cost, nontoxicity, and high-performance CuSCN-based PD and broadening its applications.