Poly(3,4-ethylenedioxythiophene) decorated MXene as an alternative counter electrode for dye-sensitized solar cells

Abstract

Counter electrodes (CE) layer in dye-sensitized solar cells (DSSCs) are possibly the most exorbitant material due to the presence of scarce earth metal, platinum (Pt). The prospective substitution of a Pt-CE would effectively pave the way for broad commercialization of the DSSC technology. In this regard, this work is focused on the fabrication of poly(3,4-ethylene dioxythiophene) decorated MXene (PEDOT@Ti3C2Tx) composite electrode, and its performance as a CE in DSSC was tested for the replacement of high-cost Pt-CE. The 2D-Ti3C2Tx was initially synthesized by the selective chemical etching method, followed by the electro-polymerization of 3,4-ethylenedioxythiophene (EDOT) monomer on the Ti3C2Tx surface. Further, X-ray diffraction (XRD), Raman, high-resolution scanning electron microscopy (HR-SEM), and X-ray photoelectron spectroscopy (XPS) characterization results confirm the successful formation of the PEDOT@Ti3C2Tx composite. PEDOT@Ti3C2Tx-CE display a strong electrocatalytic activity toward the iodide/triiodide electrolyte and good charge transfer kinetics with low charge transfer resistance close to the performance of the Pt electrode, as shown by electrochemical experiments. On the other hand, further testing of the device fabricated with thermally decomposed Pt-CE DSSCs achieved an efficiency of 8.7% under simulated 1SUN light at AM1.5G, whilst the DSSC built with the as-prepared composite material had 7.12% efficiency under the same conditions. PEDOT@Ti3C2Tx-CE composite DSSC outperformed PEDOT-CE and Ti3C2Tx-CE DSSC in power conversion efficiency improvements (PCE), demonstrating that PEDOT@Ti3C2Tx composite possesses a strong catalytic activity with noticeable charge transfer and mass transport capabilities. Therefore, the as-fabricated composite film takes utilization of the conductivity and electrocatalytic capabilities of the two components, increasing the overall power conversion efficiency of DSSC. The 15-days stability investigation demonstrates that the PEDOT@Ti3C2Tx-CE-based DSSC exhibits a consistent performance and corrosion resistant toward the iodide/triiodide redox electrolyte. Therefore, overall performance level of the PEDOT@Ti3C2Tx-CE thus entices more study for the replacement of Pt in DSSC and is indeed evinced to be a prospective noble metal electrode contender.