Enhancing the optical properties using hemisphere TiO₂ photonic crystal as the electron acceptor for perovskite solar cell

The loss of light in a solar cell is a matter of concern for the scientific community. We report on the nanostructure and dynamics of electron transport and recombination in perovskite solar cell incorporating oriented hemisphere TiO₂ arrays. The structure of the hemisphere TiO₂, which was prepared from nano-imprint technique, was characterized by SEM and AFM. By adjusting the size of polystyrene bead in imprinting process, the size of hemisphere pattern were selectively controlled to 300 nm, 700 nm, 1100 nm and 1400 nm. Hemisphere TiO₂ photonic crystals as electron transport layer lead to light scattering effect in perovskite solar cell. The 1400 nm sized of hemisphere pattern using 1600 nm polystyrene bead provided the highest light-utilization efficiency among those in the visible range, in addition recombination rate of electron transport layer was also decreased. As a result, the power conversion efficiency of perovskite solar cell was improved from 10.5 to 15.2%.