Continuous monomer supply for highly monodisperse Ag2Te colloidal quantum dots for SWIR photodetectors

Abstract

Silver telluride (Ag2Te) colloidal quantum dots (CQDs) are promising semiconducting materials for infrared applications due to their narrow band gap and low toxicity. However, synthesizing large-sized Ag2Te CQDs with a uniform size distribution in the short-wave infrared (SWIR, 900-1700 nm) range remains a challenge. Here, we present a continuous monomer supply strategy that achieves homogeneous, large-sized CQDs with precise control over the growth phase. The continuous monomer supply prevents the monomer concentration from reaching the equilibrium point at which Ostwald ripening becomes the dominant growth mechanism. At an optimal balance between monomer supply and consumption, the CQDs exhibit controlled growth from 2.5 to 4.6 nm, corresponding to first excitonic peaks between 900 and 1718 nm, while the half-width at half-maximum decreases from 143 to 62 meV. SWIR photodetectors fabricated with these CQDs demonstrate a responsivity of 2.0 mA W-1 under 1550 nm laser irradiation.