Facile, substrate-scale growth of mono- and few-layer homogeneous MoS₂ films on Mo foils with enhanced catalytic activity as counter electrodes in DSSCs

The growth of MoS₂ films by sulfurization of Mo foils at atmospheric pressure is reported. The growth procedure provides, in a controlled way, mono- and few-layer thick MoS₂ films with substrate-scale uniformity across square-centimeter area on commercial foils without any pre- or post-treatment. The prepared few-layer MoS₂ films are investigated as counter electrodes for dye-sensitized solar cells (DSSCs) by assessing their ability to catalyse the reduction of I₃ ^– to I^– in triiodide redox shuttles. The dependence of the MoS₂ catalytic activity on the number of monolayers is explored down to the bilayer thickness, showing performance similar to that of, and stability against corrosion better than, Pt-based nanostructured film. The DSSC with the MoS₂–Mo counter electrode yields a photovoltaic energy conversion efficiency of 8.4%, very close to that of the Pt–FTO-based DSSC, i.e. 8.7%. The current results disclose a facile, cost-effective and green method for the fabrication of mechanically robust and chemically stable, few-layer MoS₂ on flexible Mo substrates and further demonstrate that efficient counter electrodes for DSSCs can be prepared at thicknesses down to the 1–2 nm scale. (paper)