Enhanced photoresponse behavior of Au@Bi2Te3 based photoelectrochemical-type photodetector at solid-solid-liquid joint interface

Mixed low-dimensional nanomaterials as recently reported are most likely to achieve high energy gain and photoresponsivity for its quantum confinement properties and strong light-matter interaction. In this work, we have fabricated 1% Au–Bi2Te3, 3% Au–Bi2Te3 and 5% Au–Bi2Te3 mixed low-dimensional materials by using a two-steps chemical method. Both responsivity and photoconversion efficiency of 3% Au–Bi2Te3 are much higher than that of pure Bi2Te3 or other composite materials. The responsivity of 3% Au–Bi2Te3 varies from 0.13 μA W−1 at 0.3 V to 220 μA W−1 at 1.0 V in 1 M KOH electrolyte, and nearly 2000-fold enhancement on the responsivity is induced by bias potential. Meanwhile, the mechanism of the photoelectrochemical (PEC)-enhanced photodetector has been elucidated under KOH electrolytes with different concentration as electrolyte. We found that formation of semiconductor-metal-electrolyte junction in solid-solid-liquid space charge region can broaden light absorption range and enhance photo-conversion efficiency at the meantime. It is further anticipated that the current work might provide a new insight into the construction of high performance photodetector, while the studies on the role of solid-solid-liquid space charge region and their advantages can be extended to other PEC-based devices.