Superhydrophobic SnO2 nanowire/graphene heterostructure-based ultraviolet detectors

As ultraviolet (UV) sensors are often employed in external environments, they should be able to function efficiently outdoors while remaining unaffected by liquids or changes in humidity. In this study, we developed a tin (IV) oxide nanowire (SnO2 NW)/graphene heterostructure-based UV detector that can accurately detect UV light without being affected by exposure to liquids. A (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl) phosphonic acid (HDF–PA) passivation layer was self-assembled on an SnO2 NW/graphene heterostructure sensing channel to make its surface superhydrophobic (contact angle of ∼154°). This configuration prevents UV sensing distortion due to current leakage in case the sensor is exposed to various liquids. HDF–PA, which is less than 1.5 nm thick, slightly reduces UV transmission, rendering it a suitable passivation material to repel external liquids. In addition, the heterostructure of SnO2 NWs and graphene, as a UV sensing channel, can provide higher UV sensitivity than that of pristine graphene. The proposed method can be applied to fabricate stable, sensitive, and robust optical sensors that can withstand various environmental conditions.