W₁₈O₄₉ Nanowire Arrays for Plasmonic Photodetector with Electromediated Broadband Photoresponse

Plasmonic semiconductors offer significant advantages for the development of photodetectors with a tunable wide spectral response. Herein, we developed a plasmonic semiconductor photodetector based on the W 18 O 49 nanowire array (NWA) to achieve a tunable broadband photodetector by adjusting the plasmonic absorption intensity of the W 18 O 49 NWA. The plasmonic absorption intensity could be mediated through adjusting the free electron density of the W 18 O 49 NWA by applying the external voltage on the W 18 O 49 NWA-loaded electrode in HCl electrolyte. When the applied voltage decreased from +2 to −2 V, the plasmonic absorption intensity of the W 18 O 49 NWA gradually enhanced due to the increased electron density. As a result, the responsivity and detectivity of the W 18 O 49 NWA-based photodetector in the visible–NIR region were dramatically increased. Especially, upon 940 nm illumination, the responsivity and detectivity could reach ∼47.2 mA W –1 and ∼8.22 × 10 9 Jones, respectively, which is much higher than the corresponding values (∼2.9 mA W –1 and ∼4.53 × 10 9 Jones) obtained by the W 18 O 49 NWA-based photodetector with a low plasmonic absorption. This work proposes a promising strategy to construct broadband-tunable photodetectors by using low-cost nonmetallic plasmonic nanostructures.