Cation-Exchange Synthesized CdTe/HgTe Core/Shell Quantum Dots as Hole Transport Layers for HgTe Quantum Dot Photodetectors

HgTe colloidal quantum dots (CQDs) possess an ultra-broad spectral response, good air stability, and tunable surface chemistry, making them a promising candidate material for next-generation infrared photodetectors. However, the development of HgTe CQD infrared photodetectors has been hindered by the limited availability of favorable hole transport layers (HTLs). Herein, we report high-quality HTLs based on CdTe/HgTe core/shell CQDs. The CdTe/HgTe CQDs were synthesized via a facile cation exchange strategy using CdTe CQDs. Based on the CdTe/HgTe CQD HTL, a p-on-n structure HgTe CQD photodiode was fabricated. An external quantum efficiency of 50.5% and a specific detectivity D* of 1.73 × 1012 Jones at a wavelength of 1600 nm were achieved. Subsequently, the device was successfully employed for infrared imaging. This study identifies a facile approach for the fabrication of high-quality HTLs for HgTe CQD photodiodes.