Photovoltaic (PV) technology is considered a potential candidate for generating clean and renewable energy to fulfill the ever-increasing world energy demand. Among the different generations of PV technology, dye-sensitized solar cells (DSSCs) have attracted considerable focus due to their favorable factors like flexible and user-friendly design, environment-friendly nature, and operatable at dim light conditions. A typical DSSC consists of dye sensitized mesoporous TiO₂ photoanode, redox electrolyte and counter electrode (CE). Most commonly used Pt CE consumes around half of the total cost of DSSCs, and also it reacts with iodine-based electrolytes and decomposes to PtI₄, thus affecting its long-term stability and commercialization. Hence, the exploration of Pt-free materials has been the focus of current researchers worldwide. In this direction, two-dimensional transitional metal carbides, MXene, with unique optoelectronic properties, have recently received worldwide attention due to their easily modifiable functional groups, and are being researched in a variety of energy storage and conversion applications.

In the present work, thin films of MXene (Ti₃C₂T_X) were produced on fluorine-doped tin oxide (FTO) substrates using its various concentrations in isopropyl alcohol (10, 30, 50 mg/ml), named M10, M30, and M50. The samples have been characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Raman spectroscopy to investigate their structural, and optical characteristics. MXene films were then employed as a CE in the fabrication of low-cost DSSCs without the usage of highly expensive Pt material. It has been observed that MXene based CE in DSSCs with a 30 mg/ml concentration have a higher power conversion efficiency (PCE) as compared with other concentrations, which can be related to their uniform and homogenous surface. In addition, the photovoltaic performance of optimized MXene-based DSSC is nearly the same as that of ordinary Pt-based DSSCs. It is attributed to the dramatic decrease in the charge transfer resistance at the CE-electrolyte interface, which arises due to the presence of a large number of active sites for reduction and oxidation reactions to take place, resulting in faster oxidation and reduction reactions in DSSCs. It further lowers the recombination reaction rate and is confirmed from the Nyquist plots obtained from electrochemical impedance spectroscopy (EIS). The results demonstrated the merits of optimization of MXene concentration for generating efficient interfacial charge transfer processes and enrichment of the electrocatalytic activity of MXene for DSSCs.