Spontaneously Healing Buried Interfaces in n-i-p Halide Perovskite Photovoltaics

Accumulated halide defects on the buried interfaces of halide perovskite layers have exacerbated undesirable nonradiative recombination in the n-i-p perovskite photovoltaics, but are challenging to be passivated-the commonly used passivation molecules at buried interfaces of perovskite layers would be inevitably eroded in the solution processes of perovskite deposition. Regarding the solvent incompatibility, herein, the ZnO-EA/SnO2-Cl electron transfer layers (ETLs) terminated with functional sites (i.e., ethanolamine (EA) ligands on ZnO and Cl- ions on SnO2) to spontaneously heal the buried interfaces of perovskite layers are customized. The specialties of ZnO-EA/SnO2-Cl for defect passivation are revealed: 1) formation of ZnO-EA-Pb2+ coherent interlayers at the EA-terminated ZnO-perovskite interfaces effectively offsets the I vacancy defects of perovskites; and 2) spontaneous halide exchange between Cl--terminated SnO2 and unstable I--terminated perovskites enables the formation of FA(2)Sn(ICl)(6)-like coherent interlayers. Thus, the customized termination of ETLs' surface reduces the halide-defect-triggered nonradiative recombination at the buried surfaces of perovskite, enabling the fabricated n-i-p planar modules (6 x 6 cm(2)) with power conversion efficiencies approaching 18% and elevated stability. These findings provide desirable guidelines for interfacial carrier transport between perovskites and ETLs.