Solution-processed, binder-free pristine Ti3C2Tx MXene electrodes enabled by MAI passivation for high-performance, scalable perovskite solar cells

While carbon electrodes offer a cost-effective option for perovskite solar cells (PSCs), their efficiency is often compromised by the insulating polymer binders required. Addressing this limitation, we demonstrate a polymer binder-free electrode using pristine Ti₃C₂T_x MXene, applied directly onto the perovskite via a simple solution-processing technique. A major obstacle emerged: the direct interface between untreated, hydrophilic Ti₃C₂T_x and the perovskite proved unstable, causing rapid degradation. We resolved this critical issue by introducing a novel methylammonium iodide (MAI) surface treatment for Ti₃C₂T_x prior to deposition. This passivation strategy proved essential, stabilizing the interface by neutralizing reactive surface groups. PSCs utilizing these MAI-treated, binder-free Ti₃C₂T_x electrodes achieved 13.8 % power conversion efficiency, substantially exceeding carbon controls (10.7 %), primarily due to a significantly enhanced fill factor (75.2 % vs 58.2 %) and low sheet resistance. Furthermore, demonstrating practical potential, these MXene electrodes maintain performance better than carbon when the active area is scaled up. Although encapsulation is required to protect the hydrophilic MXene and ensure long-term stability (>360 h) in ambient conditions, this work charts an effective course for developing highly conductive, scalable, binder-free electrodes for advanced PSCs.