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

• First successful fabrication of polymer binder-free Ti 3 C 2 T x MXene electrode directly onto a perovskite layer via simple solution-processing, without the need for polymer additives and thermal processing. • Solvent Exchange Technique: Utilized solvent exchange to deposition of Ti 3 C 2 T x on top of the perovskite layer without damaging the underlying structure. • Chemical degradation of the methylammonium lead iodide perovskite layer when in contact with Ti 3 C 2 T x MXene. • Solution Introduced: A methylammonium iodide (MAI) surface treatment that passivates the MXene surface, stabilizing the electrode–perovskite interface. • Performance Boost: Power conversion efficiency improved to 13.8 % (compared to 10.7 % with carbon electrodes). • Fill factor increased significantly: 75.2 % (vs. 58.2 %), attributed to: Elimination of resistive binders, High conductivity of Ti 3 C 2 T x MXene. • Scalability Advantage: Superior performance retention upon active area scaling, making it promising for larger, practical devices. • Stability Consideration: Due to the hydrophilic nature of Ti 3 C 2 T x , encapsulation is required for long-term ambient stability (>360 h). 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 Ti 3 C 2 T x MXene, applied directly onto the perovskite via a simple solution-processing technique. A major obstacle emerged: the direct interface between untreated, hydrophilic Ti 3 C 2 T x and the perovskite proved unstable, causing rapid degradation. We resolved this critical issue by introducing a novel methylammonium iodide (MAI) surface treatment for Ti 3 C 2 T x prior to deposition. This passivation strategy proved essential, stabilizing the interface by neutralizing reactive surface groups. PSCs utilizing these MAI-treated, binder-free Ti 3 C 2 T 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.