Solution-Processed, High-Performance, Transparent Near-Infrared Photodetectors Based on Ag x Te Colloidal Quantum Dot–Decorated SnO2 Channels

In this study, high-performance near-infrared (NIR) phototransistors were developed based on tin dioxide (SnO2) thin films decorated with AgxTe colloidal quantum dots (CQDs). The hybrid SnO2/AgxTe architecture was designed to overcome the intrinsic limitations imposed by the wide bandgap of SnO2, enabling NIR photodetection beyond its native absorption range. Structural and morphological characterizations confirmed the formation of polycrystalline SnO2 and the homogeneous dispersion of AgxTe CQDs across the film surface. Optical analyses revealed a significant reduction in the effective optical bandgap to ∼1.3 eV upon AgxTe CQD incorporation, accompanied by enhanced NIR absorption. Electrical measurements demonstrated that devices decorated with 0.3 and 0.5 wt % AgxTe CQDs exhibited strong NIR photoresponses. Notably, the device containing 0.3 wt % AgxTe achieved comparable or, for some metrics, superior performance, including detectivity (∼3.77 × 1011 Jones), responsivity, and photosensitivity, despite its lower CQD loading. The AgxTe CQDs were well distributed on the SnO2 films, occupying a relatively small surface area fraction. These findings indicate that optimized NIR photodetection can be achieved with a minimal quantum dot content, offering a promising route toward cost-effective, transparent, and high-performance phototransistor applications without compromising visible-range transparency.