High-Performance Inverted Near-infrared Organic Photodetectors Enabled by Interface Passivation and Optical Engineering

Abstract

A dual interfacial–optical engineering approach has been developed for high-performance, transparent inverted near-infrared (NIR) organic photodetectors (OPDs) tailored for imaging sensors. Surface defects of the zinc oxide (ZnO) electron-transporting layer (ETL) were passivated with a thin noroxylin interlayer, resulting in significant suppression of dark current through reduced trap-assisted recombination and improved interfacial energetics, which facilitated efficient charge extraction. Concurrently, NIR absorption enhancement was realized by incorporating an upper transparent electrode integrated with an optical coupling layer, designed via transfer-matrix simulations for optimal spectral response in the NIR region. The synergistic combination of these strategies yielded transparent inverted NIR OPDs with a specific detectivity of 5.08 × 1012 Jones at 835 nm under –1.0 V, representing a 4-fold improvement over control devices utilizing a pristine ZnO ETL. Integration of the optimized OPDs with a 64 × 64 Si-based thin-film transistor array (pixel size: 500 × 500 μm) enabled highly sensitive and clear real-time NIR imaging, demonstrating the practical potential of this approach for applications in advanced NIR image sensors.