화학과

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 (MWIR) tunable Ag₂Te colloidal quantum dot (CQD) through a post-growth method starting from short-wavelength infrared Ag₂Te CQDs. Using the synthesized MWIR Ag₂Te CQDs, we successfully fabricated a MWIR photodetector covering the full MWIR 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^-3 A/W at 0.02 V to 1.1 A/W at 0.5 V, depending on the applied bias, and the specific detectivity (D^*) we measured from the device is 1.2 × 10⁹ Jones at 0.02 V. The measured noise-equivalent temperature difference (NETD) of 0.3 K enables us to reliably distinguish temperature variations between 37 ℃ and 40 ℃, directly enabling the diagnosis of fever-level body temperatures.

https://doi.org/10.1038/s41467-026-71374-3