Amorphous Metal Oxide Blocking Layers for Highly Efficient Low-Temperature Brookite TiO₂-Based Perovskite Solar Cells

Abstract

A fully low-temperature-processed perovskite solar cell was fabricated with an ultrathin amorphous TiO_x hole-blocking layer in combination with brookite TiO₂ prepared at temperature <150 °C. Structured with TiO_x/brookite TiO₂ bilayer electron collector, the perovskite solar cells exhibit high efficiency up to 21.6% being supported by high open-circuit voltage and fill factor up to 1.18 V and 0.83, respectively. Compared to SnO_x hole-blocking layer, TiO_x has better electron band alignment with brookite TiO₂ and hence, results in higher efficiency.