High-sensitivity and high-stability near-ultraviolet self-powered photodetectors enabled by depolarization electric field and core-shell structured Cu@benzotriazole nanowire electrode

Abstract

Currently semiconductor-based near ultraviolet and ultraviolet self-powered photodetectors usually display low detectivity and responsivity due to weak photogenerated electron and hole separation ability and not suitable electrode. BaTiO3 possesses a high depolarization electric field throughout the bulk and wide band gap (> 3 eV), and hence is a good candidate for fabricating near-ultraviolet and ultraviolet self-powered photodetectors. Cu nanowires (NWs) have been regarded as promising transparent electrode for photodetectors because they have not only equivalent optical transparency and electrical conductivity relative to Ag NWs currently in use, but also far lower cost. But, weak resistance to oxidation in the environment of light and electricity prevents large-scale use of Cu NWs in photodetectors. Herein, an organic corrosion inhibitor, benzotriazole (BTA), is used to passivate Cu NWs, and interestingly, the passivated NW networks exhibit significantly increased resistance to oxidation. At zero field, the BaTiO3 photodetector coated with Cu@BTA NWs exhibits stable photocurrent, high responsibility of 6.45 × 10−7A/W, large detectivity of 1.97 × 108 Jones, and fast response rate (rise and decay time being 28.8 ms and 37.2 ms, respectively) at the wavelength of 405 nm, which is far better than indium-tin-oxide electrode-coated BaTiO3 photodetector. This work provides a strong guideline for large-scale fabrication of low-cost and high-stability transparent electrodes applicable in near-ultraviolet and ultraviolet photoelectric devices.