Chemical Polishing-Assisted Surface Passivation and Repair for Robust Perovskite Photovoltaics

Defects on perovskite film surfaces are thought to be detrimental to device efficiencies and stabilities of perovskite solar cells, thereby minimizing the surface defects is critical for high performance. Here, we present a chemical polishing-assisted molecular passivation strategy to repair the perovskite surface, in which trace amounts of N,N-dimethylformamide are employed to mildly dissolve the surface and remove residual PbI₂, while 2-amino-4,6-dimethoxy-1,3,5-triazine (ADT) acts as a molecular repair agent. First-principle calculations and experiments show that amino and methoxy groups in ADT passivate defect states with different charge characteristics in perovskite via electrostatic forces, significantly reducing the defect density. Consequently, smooth and homogeneous perovskite films are obtained with released residual stress, suppressed non-radiative recombination, and superior long-term stability under both light soaking and humid conditions. The target perovskite solar cells show a power conversion efficiency of 25.05% and exhibit markedly improved stability, with the extrapolated T₈₀ exceeding 4100 h under the ISOS-D-1I protocol and the T₈₀ lifetime over 2200 h loading maximum power point tracking following the ISOS-L-1I protocol. The devices also maintain stable photocurrent under prolonged light on-off cycling. Our work offers a new and convenient strategy for perovskite surface repair to achieve efficient and robust perovskite optoelectronic devices.