Pressure-induced enhancement of optoelectronic properties in PtS2**Project supported by the National Key Research and Development Program of China (Grant Nos. 2018YFA0305700 and 2016YFA0401804), the National Natural Science Foundation of China (Grant Nos. 11574323, 11704387, U1632275, 11304321, 11604340, and 61774136), the Natural Science Foundation of Anhui Province, China (Grant No. 1708085QA19), and the Director’s Fund of Hefei Institutes of Physical Science,

Abstract

PtS2, which is one of the group-10 transition metal dichalcogenides, attracts increasing attention due to its extraordinary properties under external modulations as predicted by theory, such as tunable bandgap and indirect-to-direct gap transition under strain; however, these properties have not been verified experimentally. Here we report the first experimental exploration of its optoelectronic properties under external pressure. We find that the photocurrent is weakly pressure-dependent below 3 GPa but increases significantly in the pressure range of 3 GPa–4 GPa, with a maximum ∼ 6 times higher than that at ambient pressure. X-ray diffraction data shows that no structural phase transition can be observed up to 26.8 GPa, which indicates a stable lattice structure of PtS2 under high pressure. This is further supported by our Raman measurements with an observation of linear blue-shifts of the two Raman-active modes to 6.4 GPa. The pressure-enhanced photocurrent is related to the indirect-to-direct/quasi-direct bandgap transition under pressure, resembling the gap behavior under compression strain as predicted theoretically.