Synergistic enhancement of DSSC performance via Ti3C2 MXene-modified copper redox electrolytes: Mechanistic insights into charge transfer and recombination

Abstract

Abstract

The incorporation of Ti3C2 MXene micro-nano sheets into a copper complex redox mediator electrolyte resulted in significant improvements in charge transport and recombination suppression for dye-sensitized solar cells (DSSCs). The device fabricated using the incorporation of Ti3C2 MXene at an optimized loading of 0.5 wt% in the copper complex redox mediator electrolyte reached a champion power conversion efficiency (PCE) of 7.45 % under 1-Sun illumination. This performance enhancement is attributed to MXene's high electrical conductivity and its effective passivation of trap states, which collectively bolster charge transport and dye regeneration in DSSCs. These findings underscore the transformative potential of well-dispersed MXene micro-nanosheets to synergistically improve ionic conductivity and reduce recombination losses in copper complex redox mediators. X-ray diffraction analysis proved that Cu complex engagement with MXene also enhances the layering structure of MXenes. Mechanistic studies via electrochemical impedance spectroscopy and intensity-modulated spectroscopies indicate that the MXene-modified electrolyte reduces back-recombination losses by 14.20 % and extends carrier lifetimes. Under 10 % sunlight, the device maintains a PCE of 12.51 %, underscoring its potential for low-light Internet-of-Things (IoT) applications. These findings open a pathway for engineering MXenes in advanced electrolytes to achieve synergistic improvements in the stability and performance of DSSCs.