Ternary Ag-Te-S colloidal quantum dots for shortwave infrared photodetectors

Abstract

Ecofriendly silver telluride (Ag2Te) colloidal quantum dots (QDs) are promising for shortwave infrared (SWIR) photodetectors. However, the performances of the devices–especially beyond 1.5 μm–remain constrained photoelectric conversion efficiency due to inefficient charge extraction. Here, we develop a ternary Ag-Te-S QDs via sulfur (S) pre-injection strategy. The incorporation of S atoms in Ag2Te crystal lattice suppresses the particle fusion, improves structural uniformity, and prolongs the exciton dynamics. By integrating the ternary Ag-Te-S QDs into SWIR photodiodes, the devices achieve a state-of-the-art external quantum efficiency (EQE) of 26% beyond 1.5 mm under 0 V bias at room temperature. We finally demonstrate SWIR fluorescence imaging by using the Ag-Te-S QD photodiodes. This work establishes a practical polynary alloy design to overcome charge-extraction bottlenecks in colloidal QD photoactive layers for eco-friendly high-performance SWIR photodetection.