CuS/WS2 and CuS/MoS2 heterostructures for high performance counter electrodes in dye-sensitized solar cells

In this work, we demonstrated CuS/WS2 and CuS/MoS2 heterostructures via a sputtering-CVD process for dye sensitized solar cells (DSSCs) as a counter electrode (CE) to replace the currently preferred expensive platinum (Pt). The cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel curve studies revealed that the unique CuS/WS2 and CuS/MoS2 heterostructures were beneficial in achieving high electrocatalytic activity, low charge-transfer resistance at the CE/electrolyte interface, and fast reaction kinetics for the reduction of triiodide to iodide at the CE. The constructed DSSCs using these CuS/WS2 and CuS/MoS2 CEs exhibited high-power conversion efficiencies (PCEs) of 8.21% and 7.12%, respectively, which are comparable to conventional Pt CE (8.74%) and pristine WS2, MoS2, and CuS CEs (6.0%, 6.3% and 6.4%). This novel sulfur based heterostructure opens up opportunities for a variety of optoelectronic and photoelectrochemical applications.