Vertical Nb2O5 micro-petal array photoelectrochemical deep-UV photodetectors for underwater weak-light photodetection

Abstract

Photoelectrochemical solar-blind ultraviolet photodetectors (PEC SBUV PDs) are particularly well-suited for marine environments. However, two critical factors are often overlooked when applying PEC SBUV PDs in natural marine environments: weak light intensity and temperature variability in the ocean. Therefore, designing high-performance PEC SBUV PDs for weak light detection under varying environmental conditions is attractive. Herein, Nb₂O₅ micro-petal arrays (MPAs) on FTO glasses were obtained by a simple hydrothermal method, followed by an annealing process. The self-powered Nb₂O₅ MPA PEC SBUV PDs in simulated seawater exhibit a high responsivity of 146.44 mA W⁻¹ under weak 254 nm light irradiation (19.9 μW cm⁻²), a fast response speed of 80/90 ms, an ultrahigh solar-blind/visible blind rejection ratio of 22 306, and excellent multicycle stability with only a 0.7% decay after 1000 cycles. In addition, Nb₂O₅ MPA PEC SBUV PDs exhibit strong long-term stability, maintaining a responsivity of 109.02 mA W⁻¹ even after 150 days of storage. Moreover, Nb₂O₅ MPAs exhibited good UV photoresponse in harsh environments across a broad range of temperatures (5, 25, and 45 °C), including acidic electrolyte (0.1 M H₂SO₄), alkaline electrolyte (0.1 M KOH), and simulated seawater, highlighting their potential for applications in underwater optoelectronic devices.