Synergistic Additive Engineering with Sulfur-Terminated Ti3C2Tx MXene towards Efficient and Stable Perovskite Solar Cells
Two-dimensional MXene Ti3C2Tx demonstrates great promise in perovskite solar cells (PSCs). Herein, sulfur-terminated Ti3C2Tx (S-Ti3C2Tx) is developed by modifying Ti3C2Tx via a facile hydrothermal method using thioacetamide. As a perovskite additive, S-Ti3C2Tx outperforms pristine Ti3C2Tx by (1) significantly promoting grain growth, enhancing carrier mobility, and reducing defect density; (2) optimizing energy level alignment to lower interfacial energy barriers and minimize interface non-radiative recombination; (3) stabilizing uncoordinated Pb2+ and [PbI6]4− octahedra via Pb–S bonds while alleviating bulk lattice strain, as this Pb–S interaction exerts a “tape-like” effect. Based on this synergistic mechanism, PSCs with S-Ti3C2Tx achieve a champion efficiency of 25.51%—outperforming control (23.46%) and pristine Ti3C2Tx-based devices (24.54%)—with enhanced stability. This work highlights terminal group engineering as a critical strategy for advancing high-performance PSCs and their potential for emerging photovoltaic technologies.