Carbon-Based All-Inorganic CsPbI2Br Perovskite Solar Cells Using TiO2 Nanorod Arrays: Interface Modification and the Enhanced Photovoltaic Performance

Recently, carbon-based all-inorganic perovskite solar cells (PSCs) caught the attention of photovoltaic researchers due to their remarkable stability. Herein, we report a carbon-based all-inorganic CsPbI2Br PSC using TiO2 nanorod arrays (TiO2 NRAs) as an electron transporting layer. The method of using TiO2 NRAs as an electron pathway has the advantage of increasing the electron–hole separation effectively and enables a thicker active perovskite layer to obtain a stronger absorbance. In addition, a water–alcohol soluble CsCl was used to modify the interface between TiO2 NRAs and the CsPbI2Br active layer to reduce interfacial recombination of charge carriers in the cells, and the CsCl interface-modified device showed a 10.6% increase in the open-circuit voltage. An optimized power conversion efficiency of 11.45% has been obtained, which is one of the superior performances reported for the carbon-based pure CsPbI2Br PSCs to date.