A novel CdHgTe electron transport layer for high-performance HgTe colloidal quantum dot infrared photodetectors

HgTe colloidal quantum dots (CQDs) photodetectors, owing to their advantages of low cost and facile integration, are anticipated to be the optimal choice for the next-generation of short-wave infrared (SWIR) detection technology. However, narrow-bandgap HgTe CQDs exhibit a very high electron affinity, resulting in the conduction band energy level being excessively low. The energy levels of most electron transport layers (ETLs) are difficult to align, leading to a decrease in charge extraction efficiency. To address this issue, we developed a novel CdHgTe CQDs ETL film for the first time by utilizing the cation exchange strategy of CdTe CQDs. The exchange reaction of partly substituting Cd 2+ with Hg 2+ within the thin film can reduces the surface potential, increase its work function, and thereby facilitates favorable energy level matching with the HgTe CQDs layer, enabling the fabrication of a n-i-p HgTe CQDs SWIR photodetector with ultra-low dark current density characteristics, reaching as low as 9.45 × 10 −5 mA/cm 2 at −1.0 V bias, and a specific detectivity of 7.41 × 10 11 Jones at 1560 nm. Finally, we integrated it into a 64 × 64 SWIR imager and demonstrated its object recognition applications in various scenarios, thereby establishing a robust foundation for enriching the design of HgTe-based infrared detector devices and broadening their application scope.