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

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.