Engineering Band Gap of Ternary Ag₂Te_xS_1−x Quantum Dots for Solution-Processed Near-Infrared Photodetectors

• Published in: Inorganics
• Main Authors: Zan Wang, Yunjiao Gu, Daniil Aleksandrov, Fenghua Liu, Hongbo He, Weiping Wu
• Format: Article
• Language: English
• Published: MDPI AG 2023-12-01
• Subjects: Ag₂Te_xS_1−x QDs; ternary alloying; band gap engineering; photodetectors
• Online Access: https://www.mdpi.com/2304-6740/12/1/1

Silver-based chalcogenide semiconductors exhibit low toxicity and near-infrared optical properties and are therefore extensively employed in the field of solar cells, photodetectors, and biological probes. Here, we report a facile mixture precursor hot-injection colloidal route to prepare Ag₂Te_xS_1−x ternary quantum dots (QDs) with tunable photoluminescence (PL) emissions from 950 nm to 1600 nm via alloying band gap engineering. As a proof-of-concept application, the Ag₂Te_xS_1−x QDs-based near-infrared photodetector (PD) was fabricated via solution-processes to explore their photoelectric properties. The ICP-OES results reveal the relationship between the compositions of the precursor and the samples, which is consistent with Vegard’s equation. Alloying broadened the absorption spectrum and narrowed the band gap of the Ag₂S QDs. The UPS results demonstrate the energy band alignment of the Ag₂Te_0.53S_0.47 QDs. The solution-processed Ag₂Te_xS_1−x QD-based PD exhibited a photoresponse to 1350 nm illumination. With an applied voltage of 0.5 V, the specific detectivity is 0.91 × 10¹⁰ Jones and the responsivity is 0.48 mA/W. The PD maintained a stable response under multiple optical switching cycles, with a rise time of 2.11 s and a fall time of 1.04 s, which indicate excellent optoelectronic performance.