Large area growth of MoTe₂ films as high performance counter electrodes for dye-sensitized solar cells

A cost effective and efficient alternative counter electrode (CE) to replace commercially existing platinum (Pt)-based CEs for dye-sensitized solar cells (DSSCs) is necessary to make DSSCs competitive. Herein, we report the large-Area growth of molybdenum telluride (MoTe₂) thin films by sputtering-chemical vapor deposition (CVD) on conductive glass substrates for Pt-free CEs of DSSCs. Cyclic voltammetry (CV), Tafel curve analysis, and electrochemical impedance spectroscopy (EIS) results showed that the as-synthesized MoTe₂ exhibited good electrocatalytic properties and a low charge transfer resistance at the electrolyte-electrode interface. The optimized MoTe₂ CE revealed a high power conversion efficiency of 7.25% under a simulated solar illumination of 100 mW cm^-2 (AM 1.5), which was comparable to the 8.15% observed for a DSSC with a Pt CE. The low cost and good electrocatalytic properties of MoTe₂ thin films make them as an alternative CE for DSSCs.