Concurrent efficiency and stability gains in inverted perovskite solar cells enabled by termination-engineered MXene interfaces

Inverted perovskite solar cells are strongly affected by buried-interface losses at the hole-selective contact. Here, we report a UV–ozone-assisted surface-engineering strategy to tune the surface terminations of Ti 3 C 2 T x MXene for inverted perovskite solar cells. Mild UV–ozone treatment enriches Ti–O–Ti species while reducing Ti–OH groups on the MXene surface. This termination modulation adjusts the electronic structure of Ti 3 C 2 T x , increasing its work function and narrowing the energy-level offset with the perovskite valence band at the buried hole-selective contact. The resulting Ti 3 C 2 T x /MeO-2PACz self-assembled monolayer (SAM) buried interface promotes interfacial hole extraction and suppresses nonradiative recombination, lowering the trap density. As a result, devices incorporating UV-treated Ti 3 C 2 T x achieve a champion power conversion efficiency of 22.46%, compared with 19.97% for devices based on untreated Ti 3 C 2 T x . The optimized devices also show improved durability, retaining 81% and 80% of their initial efficiencies after 168 h under thermal stress and ambient storage, respectively. These results demonstrate that surface-termination engineering of MXene provides an effective route to simultaneously improve interfacial energetics, charge transport, and stability in inverted perovskite solar cells.