Constructing liquid metal/semiconductor interface for self-powered photoelectrochemical-type visible light photodetectors

Directly growing oxides on the surface of liquid metal (LM) offers a novel strategy to effectively integrate flexible conductive substrate with semiconductive layer for functional devices including photodetectors. Gallium-based liquid metal with native oxides surface typically demonstrates such LM/semiconductor construction with attractive photoelectric responsivity, however, the relevant photo-electrode lacking efficient response to visible light due to the wide band-gap of Ga-oxides. This paper presents a straightforward fabrication route containing printing and in-situ reaction growing for the preparation of liquid metal functionalized with narrow-band gap semiconductor ( e.g. , Cu 2 O). The resulting LM/metal-oxides heterostructure exhibits a well-matched liquid–solid contact and good interfacial charge transfer between the soft conductive substrate and active surface components. Characterizations including scanning electron microscopy (SEM), Raman spectroscopy, and UV–visible absorption spectroscopy confirm the successful preparation of the Cu 2 O thin layer with an expanded absorption spectrum range. The as-fabricated photoelectrode consisted of LM-Cu 2 O, through photoelectrochemical (PEC) tests, presents fast photo-responsibility under the simulated sunlight illumination and self-powered capability. Specifically, the LM-Cu 2 O based PEC photodetector shows maximum photoresponsivity of − 70 μA/W and photocurrent density of − 9.5 μA/cm 2 at a bias voltage of 0 V. Our results provide a general method for the design and manufacture of novel photodetectors.