Position-Dependent MXene Interface Engineering Enables Efficient Charge Extraction for High-Performance Ag₂Te Colloidal Quantum Dot Infrared Photodetectors

Silver telluride (Ag₂Te) colloidal quantum dots (CQDs) are promising infrared (IR) absorbers without heavy metals due to their adjustable bandgap, environmental friendliness, and solution processability, yet photodetector performance is frequently hindered by inferior charge transport, interfacial recombination, and surface trap states. In this study, an interfacial engineering strategy utilizing Ti₃C₂T_x MXene is applied to improve the optoelectronic performance of Ag₂Te CQD IR photodetectors. By systematically incorporating Ti₃C₂T_x MXene into the device structure, its impact on charge extraction, carrier transport, and interface optimization is explored. As a result, a responsivity of 4.622 mA/W with a specific detectivity of 1.907 × 10¹⁰ Jones is obtained from the photodetector ITO/SnO₂/Ti₃C₂T_x/Ag₂Te/MoO₃/Ag under 0.177 mW/cm² 1550 nm illumination, with a rapid rise and decay time of 52.0 and 57.4 ms, respectively. Ultraviolet photoelectron spectroscopy indicates improved energy-level alignment and enhanced carrier extraction at the SnO₂/Ag₂Te interface following MXene integration. Finite-difference time-domain and OghmaNano simulations further support our experimental results by showing increased optical absorption, stronger electromagnetic field confinement, and greater photocarrier generation in the photodetector. This research underscores MXene-enabled interfacial engineering as an effective method for addressing charge transport challenges and offers a promising route toward high-performance, solution-processed, environmentally friendly IR optoelectronic devices.