Formation of transition metal dichalcogenides thin films with liquid phase exfoliation technique and photovoltaic applications

We report on the production of transition metal dichalcogenides (TMDCs) dispersion with high-concentration mixed-solvent strategy. The MoS2 and WS2 thin films are processed by liquid exfoliation which has advantages for residue-free, large-scale, and low-cost in TMDCs film fabrication. Various thicknesses of TMDCs films are prepared and controlled by a centrifuge process for the photovoltaic applications (5 x 5 mm scale) with gold/TMDCs/silicon/indium geometry. Based on ultraviolet photoelectron spectroscopy measurement results, the energy band diagram of the devices using MoS2 and WS2 films can be constructed. The external quantum efficiency and power conversion efficiency (PCE) of MoS2 and WS2 devices are measured with different film thicknesses. The 126-nm-thick MoS2 and 132-nm-thick WS2 film devices show the maximum PCEs of 3.55% and 2.98%, respectively, under 100 mW cm(-2) solar illumination. Thus, we demonstrate potential of MoS2 and WS2 films in photovoltaic applications.