Promoting the Hole Extraction with Co3O4 Nanomaterials for Efficient Carbon-Based CsPbI2Br Perovskite Solar Cells

Carbon-based perovskite solar cells (PSCs) have gathered much attention due to their excellent thermal stability and low cost. However, the typically used hole-conductor-free PSCs based on carbon electrodes show the worst performance due to the serious charge recombination at the perovskite/carbon interface. In this work, the efficient and stable carbon-based CsPbI 2 Br PSCs using Co 3 O 4 as the hole transport material (HTM) are fabricated and their photoelectric properties are systematically investigated. It is found that the Co 3 O 4 inorganic HTM effectively promotes photo-generated charges separation and extraction, and suppresses charge recombination at the CsPbI 2 Br/carbon electrode interface, resulting in the improved photovoltaic performance. At the optimal Co 3 O 4 concentration, the carbon-based CsPbI 2 Br PSCs achieve the maximum efficiency of 11.21% with a negligible J – V hysteresis. This work provides a novel strategy to fabricate efficient and stable all-inorganic PSCs.