Molecularly tailorable metal oxide clusters ensured robust interfacial connection in inverted perovskite solar cells.

Interfacial recombination and ion migration between perovskite and electron-transporting materials have been the persisting challenges in further improving the efficiency and stability of perovskite solar cells (PVSCs). Here, we design a series of molecularly tailorable clusters as an interlayer that can simultaneously enhance the interaction with C₆₀ and perovskite. These clusters have precisely controlled structures, decent charge carrier mobility, considerable solubility, suitable energy levels, and functional ligands, which can help passivate perovskite surface defects, form a uniform capping net to immobilize C₆₀, and build a robust coupling between perovskite and C₆₀. The target inverted PVSCs achieve an impressive power conversion efficiency (PCE) of 25.6% without the need for additional surface passivation. Crucially, the unencapsulated device displays excellent stability under light, heat, and bias, maintaining 98% of its initial PCE after 1500 hours of maximum power point tracking. These results show great promise in the development of advanced interfacial materials for highly efficient perovskite photovoltaics.