Abstract
Redox mediators comprising I(-), Co(3+), and Ti(3)C(2)Tx MXene were applied to dye-sensitized solar cells (DSCs). In the as-prepared DSCs (I-DSCs), wherein hole conduction occurred via the redox reaction of I(-)/I(3)(-) ions, the power conversion efficiency (PCE) was not altered by the addition of Ti(3)C(2)Tx MXene. The I-DSCs were exposed to light to produce Co(2+)/Co(3+)-based cells (Co-DSCs), wherein the holes were transferred via the redox reaction of Co(2+)/Co(3+) ions. A PCE of 9.01% was achieved in a Co-DSC with Ti(3)C(2)Tx MXene (Ti(3)C(2)Tx-Co-DSC), which indicated an improvement from the PCE of a bare Co-DSC without Ti(3)C(2)Tx MXene (7.27%). It was also found that the presence of Ti(3)C(2)Tx MXene in the redox mediator increased the hole collection, dye regeneration, and electron injection efficiencies of the Ti(3)C(2)Tx-Co-DSC, leading to an improvement in both the short-circuit current and the PCE when compared with those of the bare Co-DSC without MXene.