Anatase TiO2 nanorod arrays as high-performance electron transport layers for perovskite solar cells

Abstract

One-dimensional nanorod arrays show great potential as electron transport layers of perovskite solar cells due to their unique characteristic of oriented electron transport. Herein, anatase phase TiO2 nanorod arrays are successfully grown on FTO conductive glass by a facile hydrothermal method using tetrabutyl titanate as precursor. By regulating the concentration of tetrabutyl titanate, TiO2 nanorods with the length of 50, 200, 300 and 1000 nm are synthesized. XRD and Raman spectra show that the nanorods are pure anatase phase, while SEM and TEM images reveal that they are polycrystalline structure. The anatase TiO2 nanorod array films have homogeneous surface morphologies, which are beneficial to deposit compact and pinhole-free perovskite films. The light absorption, photoluminescence quenching and trap densities of the films are systematically investigated. Consequently, the perovskite solar cells based on 50 nm anatase TiO2 nanorod arrays show the best photoelectric conversion efficiency of 15.3%, and those based on 200, 300, 1000 nm nanorod arrays achieve the photoelectric conversion efficiencies of 14.5%, 13.8% and 12.1%, respectively.