Complementary interface formation toward high-efficiency all-back-contact perovskite solar cells

Summary All-back-contact (ABC) architectures for perovskite photovoltaics represent untapped potential for higher efficiency and enhanced durability compared to conventional planar architectures. Interface engineering can be more complex in ABC designs, because both the electron and hole transport layers (ETLs/HTLs) are simultaneously exposed during processing. Herein, we fabricate ABC perovskite solar cells with a non-stabilized current-voltage scan power conversion efficiency >10% by developing complementary interface processing. UV-ozone exposure followed by annealing increases the work function and reduces the defect density of the NiOx HTL and removed contamination from the TiO2 ETL, which increases voltage and current collection. We measure the chemical composition of each transport layer interface using photoelectron spectroscopy and then use the resulting trends to inform a two-dimensional drift-diffusion model. The model suggests that further reduction of charged interface defect density, increase in the hole selective contact work function, and passivation of the front surface will enable >20% of ABC devices.