Inclined-aligned ZnO nanorod array for self-powered all-scenario underwater weak light detection and optical communication

Abstract

Underwater optoelectronic devices are core components for marine exploration and development. Photoelectrochemical-type (PEC) photodetectors, with electrolyte dependency and self-powered characteristics, are promising candidates for harsh underwater applications. Severe underwater light attenuation requires photoelectrodes to efficiently utilize photons by maximizing optical absorption and carrier separation. Herein, novel ZnO inclined nanorod arrays (INRA)-based PEC photodetectors for weak ultraviolet (UV) detection in various harsh underwater environments with different pH levels and temperatures are demonstrated. ZnO INRA was fabricated via a facile hydrothermal process without a seed layer. The ZnO INRA-based self-powered PEC photodetectors show excellent photoresponse for weak UV (365 nm, 0.089 mW/cm2), encompassing an ultrahigh responsivity of 279.8 mA/W, excellent stability (2% attenuation after 2 months storage), and outstanding spectral selectivity, which surpasses various vertical-aligned ZnO nanostructures and wide bandgap semiconductors. Enhanced performance is attributed to efficient light absorption and the large specific surface area of ZnO INRA. Moreover, the devices exhibit high, fast, and stable photoresponse in various harsh environments, including strong alkaline and acidic solutions over a broad temperature range (5 - 45 °C). Furthermore, ZnO INRA successfully transmits optical information in different underwater environments. This work validates that ZnO INRA can be applied for future multi-scenario underwater optoelectronic devices.