Improved photodetection performance enabled by gradient alloyed quantum dots

Hybrids composed of two-dimensional (2D) and zero-dimensional (0D) materials have demonstrated great application potentials in electronics and optoelectronics. The CdSe@Zn1−XCdXS (CSZCS) quantum dots (QDs) possess unique gradient band structure with a continuously increasing energy level along the radial direction from the center to the surface, which is favorable for light-harvesting, photocarrier transfer and promising for photovoltaic and photodetection applications. Here, the gradient alloyed CSZCS QDs, acting as a photosensitive layer, have been first integrated with 2D InSe as a carrier transport layer. The new 2D–0D hybrids exhibit a 300-fold improvement in responsivity compared with that of pristine InSe, which is much more superior to hybrids composed of core–shell CdSe@ZnS QDs/InSe. Thanks to the low dark current and large photo-gain induced by the photo-gating effect, the responsivity and detectivity of the CSZCS QDs/InSe photodetector can reach up to 30.16 A/W and 1.69 × 1012 Jones, respectively. This work provides a new kind of promising QDs with the gradient alloyed structure that can be explored into 2D–0D hybrids for further development of high-performance photodetectors.