Sequential surface tailoring from colloid to solid in Ag2Te colloidal quantum dots enables high hole mobility and efficient shortwave infrared photodetection

Abstract

Silver telluride (Ag2Te) colloidal quantum dots (CQDs) are promising semiconducting materials for infrared detection due to their environmentally friendly composition and tunable optical bandgap in the shortwave infrared region. However, a limited understanding of surface chemistry in Ag2Te CQDs compared to conventional II-VI and IV-VI CQD systems has hindered advancements in device performance. In this study, we present sequential surface tailoring of Ag2Te CQDs to achieve high-mobility CQD solids. This approach involves the use of a co-ligand system during colloidal synthesis to enhance ligand density and improve surface passivation, followed by iodide solid-state ligand exchange to fabricate all-inorganic Ag2Te CQD solids. As a result, the CQD solids exhibited the highest hole mobility of 3.78 cm2 V−1 s−1 among reported CQD solids. Furthermore, the enhanced carrier mobility, combined with the reduced dark current of these CQD solids, enabled photodetectors to achieve a responsivity of 27.6 mA/W under 1550 nm irradiation. © 2025 Elsevier Ltd