Structural and optical properties of 1T-MoS2/MoO3 thin films prepared by spray pyrolysis method

Abstract

Electrical properties of the devices based on two dimensional (2D) transition metal dichalcogenids thin films, is highly depended to their producing method and preparation conditions. In the present work structural and optical properties of MoS2/MoO3 nano-heterostructure films prepared by spray pyrolysis technique were studied. X-ray diffraction analysis revealed a phase transformation from hexagonal semiconducting 2H–MoS2 to octahedral metallic 1T-MoS2 phase by decreasing the molarity of ammonium molybdate as the precursor solution. The controllable phase transition provides a degree of freedom to pave the way for more novel devices. UV–Vis absorption spectra and photoluminescence (PL) spectroscopy confirm the presence of monolayer MoS2 with a direct band gap of ∼1.84 eV, related to a peak position at 674 nm in the composite. A change in the sample's band gap by annealing treatment on the hybrid films is, here reported. We found three different band gap of 1.7, 2.1 and 2.25 eV for the three composite samples and discussed the case. The highest PL quantum yield (QY) of the 1T-MoS2 based composite make it as a better candidate for photocatalysis applications. A brief discussion of the Raman spectra analysis from a prepared MoS2/MoO3 sample is also included. The present work illustrates the potential use of composite based heterostructures in electrical devises where higher conductivity of the metallic phase of MoS2 nanostructures is needed.