The Polymer Society of Korea

Abstract

Ag₂Te colloidal quantum dots (CQDs) are of great interest in shortwave infrared (SWIR) optoelectronic applications owing to their size-tunable bandgaps with high optical properties. We present a synthesis method for Ag₂Te CQDs that controls their crystal size and bandgap through chemical reactivity. This involves controlling the concentration and type of ligands, as well as the precursor ratio. The rapid termination of the reaction in this method prevents Ag₂Te CQD decomposition, yielding monodisperse CQDs with absorption and emission in the 1100−1600 nm range. We also present core/shell-type Ag₂Te/Ag₂S CQDs, which improve their chemical stability and optical properties including photoluminescence (PL) intensity. Consequently, the Ag₂Te/Ag₂S CQD-based SWIR photodetector exhibits a high external quantum efficiency of 8.4% and a specific detectivity of 1.1 × 10¹¹ Jones at 1550 nm, with a fast response time of 38 ns.