Multiple-Function Surface Engineering of SnO Nanoparticles to Achieve Efficient Perovskite Solar Cells.

The mismatched energy-level alignment and interface defects of the SnO nanoparticles' electron transport layer (ETL) and perovskite layer worsen the efficiency of the perovskite solar cell. Herein, we devise a multiple-function surface engineering of SnO nanoparticles. TBA ions improve the dispersion and stability of colloidal T-SnO nanoparticles and act as a bridge between the ETL and perovskite layer through the electrostatic interaction with anions, thus suppressing the charge recombination and reducing the energy loss. I ions passivate oxygen vacancies of SnO nanoparticles but also halide vacancies of the perovskite layer. Furthermore, the conduction band edge of T-SnO is enhanced to match the energy alignment with the perovskite, which reduces the energy offset for electron transfer. As a result, the champion solar cell based on T-SnO presented a power conversion efficiency of 21.71% with a of 1.15 V and negligible hysteresis, which are much higher than those of the reference device.