2D/1D PbI₂/Sb₂S₃ van der Waals heterojunction for highly sensitive and broadband photodetectors

Broadband photodetectors have received significant scientific interest due to their high optical gain with low energy consumption. PbI2 is an important 2D semiconductor material for electronic and optoelectronic devices. However, its limited detection capability towards visible light hinders its wide applications in the optoelectronic field. Herein, we report a novel van der Waals (vdW) 2D/1D PbI2/Sb2S3 heterojunction photodetector exhibiting broadband spectral response from 400 to 750 nm. In comparison to individual PbI2 and Sb2S3 devices, the heterojunction photodetector manifests much higher responsivity (156.3 and 120.4 A W-1), external quantum efficiency (4.4 x 10(4)% and 2.1 x 10(4)%), and detectivity (3.16 x 10(13) and 2.45 x 10(12) Jones) under 445 and 730 nm illumination, respectively. Experimental characterizations and theoretical calculations reveal the significantly enhanced photoelectric properties can be primarily ascribed to the effective separation of photogenerated electron/hole pairs facilitated by the type-II vdW heterojunction mediated by defect states. This work can provide some new insights into the fabrication of novel hybrid van der Waals heterojunctions and their applications in the optoelectronic fields.