Applying BaTiO3-coated TiO2 core-shell nanoparticles films as scaffold layers to optimize interfaces for better-performing perovskite solar cells

In this paper, we replaced mesoporous TiO2 nanoparticles scaffold layers by BaTiO3-coated TiO2 core-shell nanoparticles films which obtained by treating pure mesoporous TiO2 layers with 1.0wt% barium nitrate solution, successfully realized the aim of optimizing interfaces bonding at TiO2/CH3NH3PbI3. Ultrathin BaTiO3 shell layer can combine better with CH3NH3PbI3 layer so as to reduce the existence of carrier recombination centers. Moreover, better optical absorption and larger fill factor were obtained in this manner by the reason of larger CH3NH3PbI3 grain size and fewer crystal boundaries. Furthermore, photoluminescence spectra and electrochemical impedance spectroscopy verified that our core-shell scaffold material contributes to accelerate carrier separation and retard carrier recombination. As a result, average power conversion efficiency enhanced from 11.20 to 13.76% under ambient conditions, which realized almost a quarter improvement than the devices based on pure mesoporous TiO2 layers. Such results have a certain guiding effect on solving interface defects and carrier recombination.