Non-toxic silver telluride colloidal quantum dot mid-infrared photodetector.

Eom, So Young; Lee, Jin Hyeok; Song, Haemin; Son, Suheon; Jeong, Kwang Seob · Nat Commun · 2026

basic_science · Level V

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Abstract

As demand for sustainable and biocompatible technologies grows, low-toxicity mid-infrared materials, such as silver chalcogenides, have attracted significant interest. Herein, we report mid-wavelength infrared tunable Ag<sub>2</sub>Te colloidal quantum dots through a post-growth method starting from short-wavelength infrared Ag<sub>2</sub>Te colloidal quantum dots. Using the synthesized Ag<sub>2</sub>Te colloidal quantum dots, we successfully fabricate a photodetector covering the full mid-wavelength infrared spectral range (3-5 μm) with an onset wavelength extending to 6.9 μm. At 78 K, the photodetectors exhibit a photoresponse time of 230 ns (rise) and 576 ns (fall). Responsivity varies from 1.9 × 10<sup>-3 </sup>A W<sup>-1</sup> at 0.02 V to 1.1 A W<sup>-1</sup> at 0.5 V, depending on the applied bias, and the specific detectivity of the device is 1.2 × 10<sup>9</sup> Jones at 0.02 V. The measured noise-equivalent temperature difference of 0.3 K enables us to reliably distinguish temperature variations between 37 °C and 40 °C, directly enabling the diagnosis of fever-level body temperatures.