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

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 CsPbBr 3 perovskite NCs and wide absorption range, environment-friendly Bi 2 S 3 QDs. Our results demonstrate that the CsPbBr 3 –Bi 2 S 3 nano-heterojunction-based photodetector has higher responsivity (380 μ A/W at a wavelength of 532 nm) and higher specific detectivity (1.02 × 10 5 Jones), as compared to the individual CsPbBr 3 or Bi 2 S 3 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 Bi 2 S 3 QDs, which is not observed in the visible light absorber CsPbBr 3 devices. Remarkably, the responsivity of the heterojunction device is 90 μ A 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 CsPbBr 3 and Bi 2 S 3 QDs.