Heterostructure engineering of MXene/PEDOT:PSS/MnO2 for high-performance transparent supercapacitors

Abstract

Achieving high charge-storage capability while maintaining optical transparency remains a major challenge for transparent supercapacitors. Herein, an ultrathin interface-engineered MXene/PEDOT:PSS/MnO2 heterostructured electrode is developed, where PEDOT:PSS acts as an interfacial modulation layer to regulate MXene nanosheet stacking and construct a homogeneous conductive network, while vertically aligned MnO2 nanosheets provide abundant Faradaic active sites and efficient ion-transport pathways. Density functional theory calculations reveal strong interfacial interactions between the PEDOT backbone and Ti3C2 MXene, supporting the role of PEDOT:PSS in stabilizing the MXene framework and facilitating charge transport. The optimized composite electrode exhibits an ultrathin architecture (∼340 nm), achieving a transmittance of 78.5% at 550 nm and an areal capacitance of 6.09 mF/cm2 at 10 mV/s. The assembled symmetric transparent supercapacitor exhibits a transmittance of 68.8%, an energy density of 0.46 μWh/cm2 at a power density of 236.57 μW/cm2, and 75% capacitance retention after 3000 cycles with a Coulombic efficiency of 98%. This work demonstrates that rational regulation of film uniformity and interfacial structure through a theoretically supported interface-engineering strategy provides an effective approach for balancing optical transparency and charge-storage performance in transparent supercapacitors.