Discrete Iron(III) Oxide Nanoislands for Efficient and Photostable Perovskite Solar Cells

Perovskite solar cells typically use TiO2 as charge extracting materials, which reduce the photostability of perovskite solar cells under illumination (including ultraviolet light). Simultaneously realizing the high efficiency and photostability, it is demonstrated that the rationally designed iron(III) oxide nanoisland electrodes consisting of discrete nanoislands in situ growth on the compact underlayer can be used as compatible and excellent electron extraction materials for perovskite solar cells. The uniquely designed iron(III) oxide electron extraction layer satisfies the good light transmittance and sufficient electron extraction ability, resulting in a promising power conversion efficiency of 18.2%. Most importantly, perovskite solar cells fabricated with iron(III) oxide show a significantly improved UV light and long-term operation stabilities compared with the widely used TiO2-based electron extraction material, owing to the low photocatalytic activity of iron(III) oxide. This study highlights the potential of incorporating new charge extraction materials in achieving photostable and high efficiency perovskite photovoltaic devices.