Improving Harsh Environmental Stability of Few‐Layer Black Phosphorus by Local Charge Transfer

Abstract Few‐layer black phosphorus (FL‐BP) is a promising high‐mobility semiconductor with thickness‐dependent direct bandgap varying from visible to mid‐infrared region. The poor stability under harsh environment, stemming from irreversible oxidization of P atoms with lone pair electrons, restricts its practical applications. Herein, an electrochemical intercalation and in situ electrochemical deposition (EI&ED) approach to produce scalable Au nanoparticles/FL‐BP crystals with enhanced stability in harsh environment is developed. In this approach, the chemical reactivity of BP is significantly suppressed via the efficient local charge transfer from FL‐BP to electrochemically deposited Au nanoparticles. Thus obtained Au/FL‐BP based nano‐devices show good stability under harsh environment, including i) high humidity of 95%, ii) immersibility in organic agents for as long as 45 days, and iii) annealing at 573 K for 9 h. In addition, compared to bare FL‐BP crystals, Au/FL‐BP based photodetectors present 50‐ and 36‐fold improvement of photoresponsivity at 1550 and 1850 nm via the surface plasmonic enhancement effect. This EI&ED method can produce ultra‐stable FL‐BP crystals at large‐scale, which resolves the crucial barriers in using FL‐BP in large‐scale electronic and optoelectronic devices.