Ag Nanowire/Mo2CTx Transparent Electrodes with Chemically Tunable Work Function for Near- and Shortwave-Infrared Photodetectors

Abstract

Transparent electrodes that simultaneously combine low sheet resistance, broadband infrared transparency, and tunable interfacial energetics are critically needed for emerging infrared optoelectronics, yet are rarely achieved within a single solution-processable architecture. Here, we report a hybrid transparent electrode composed of a percolative Ag nanowire network overcoated with Mo2CTx MXene nanosheets (Ag/MX). In this architecture, Ag nanowires provide an efficient conductive scaffold, while the Mo2CTx overlayer bridges interwire junctions, smooths the surface, and governs the device-facing interfacial electronic structure. The resulting electrodes exhibit a low sheet resistance of 18.84 Ω/sq together with a transmittance of 82% at 1550 nm and an average transmittance of 80.84% over 1500–2500 nm. More importantly, two distinct surface-modification routes enable chemically tunable work-function states: polyethyleneimine lowers the work function through interfacial dipole formation, whereas UV/Ozone treatment raises it through oxygen-enriched surface termination and mild surface oxidation of the Mo2CTx overlayer. These chemically distinct low and high work function states allow the common AgNW/Mo2CTx (Ag/MX) electrode architecture to meet different carrier-selective requirements in quantum dot short-wave-infrared and organic near-infrared photodetectors. This work establishes a chemically tunable transparent-electrode platform for cross-material infrared photodetection and provides a strategy for integrating infrared transparency, electrical transport, and carrier-selective interfacial energetics within a common electrode architecture.