Extended\nShort-Wavelength Infrared Ink by Surface-Tuned\nSilver Telluride Colloidal Quantum Dots and Their Infrared Photodetection

Wavelength-tunable infrared materials, particularly those\nexcluding\nregulated substances, are essential for next-generation optoelectronics.\nSilver telluride (Ag<sub>2</sub>Te) colloidal quantum dots (CQDs)\ncan be a promising alternative to traditional Pb- or Cd-based narrow-band\ngap semiconductors due to their low toxicity. However, the strong\nbinding affinity of thiol ligands has limited the broader use of Ag<sub>2</sub>Te CQDs, necessitating more versatile surface chemistries.\nHere, we synthesized Ag<sub>2</sub>Te CQDs passivated with oleylamine,\nwhich facilitated various ligand passivation strategies. The weak\nbonding strength allows the preparation of X-Ag<sub>2</sub>Te CQD\n(X = Cl, Br, or I ligands) inks, sensitive to 1.1–2.7 μm\ninfrared radiation. Using the CQD inks, we fabricated extended short-wavelength\ninfrared (eSWIR) CQD photodiodes with two different sizes of CQDs.\nThe resulting Ag<sub>2</sub>Te CQD ink-based eSWIR photodiodes exhibited\nan external quantum efficiency of 16% at 1.7 μm at room temperature,\nrepresenting the highest value achieved for nontoxic CQD IR detectors\nat the wavelength.