Bismuth sulfide quantum dots-CsPbBr3 perovskite nanocrystals heterojunction for enhanced broadband photodetection

Abstract

Colloidal semiconductor nanocrystals (NCs) or quantum dots (QDs) have shown great potential for solution-processable photodetector due to their exceptional optical and electronic properties. However, broadband and sensitive photodetection from single QDs- based devices is quite challenging. Nano-heterojunction with proper band alignment based on two different materials offers significant advantages for developing broadband photodetector. Herein, we report ultraviolet–visible (UV–Vis) to near-infrared (NIR) light-responsive photodetector based on solution-processed nano-heterojunction of visible light absorber CsPbBr3 perovskite NCs and wide absorption range, environment-friendly Bi2S3 QDs. Our results demonstrate that the CsPbBr3–Bi2S3 nano-heterojunction-based photodetector has higher responsivity (380 μA/W at a wavelength of 532 nm) and higher specific detectivity (1.02 × 105 Jones), as compared to the individual CsPbBr3 or Bi2S3 QDs based devices. Interestingly, the detection wavelength range of our heterojunction device is further extended to the near-infrared region (1064 nm) due to the broadband absorption range of Bi2S3 QDs, which is not observed in the visible light absorber CsPbBr3 devices. Remarkably, the responsivity of the heterojunction device is 90 μA W−1. The enhanced specific detectivity and the broadband response of hybrid devices are attributed to the improved charge carrier generation, efficient charge separation and transfer at the interface between CsPbBr3 and Bi2S3 QDs.