Anchoring CuS nanoparticles on accordion-like Ti3C2 as high electrocatalytic activity counter electrodes for QDSSCs

Abstract

A Ti₃C₂/CuS composite has been fabricated as a counter electrode for quantum dot-sensitized solar cells by anchoring CuS nanoparticles on Ti₃C₂via a facile ion-exchange method at room temperature. The accordion-like Ti₃C₂ is well intercalated and coated with CuS nanoparticles at the optimized ratio of Ti₃C₂ to CuS. Both electrochemical impedance spectroscopy and Tafel polarization measurements indicate that the composite exhibits a significantly faster electrocatalytic rate towards the polysulfide reduction than pure CuS. The quantum dot-sensitized solar cell-based composite counter electrode displays an overall power conversion efficiency of 5.11% which is 1.5 times that obtained from the CuS counter electrode. The higher power conversion efficiency benefits from the improved short-circuit current density (20.86 mA cm⁻²), open-circuit voltage (0.56 V) and fill factor (0.45). The enhancement of photovoltaic performance is mainly attributed to the combined advantages of the excellent conductivity of the Ti₃C₂ skeleton and the abundant catalytically active sites of CuS nanoparticles.