A novel asymmetric phthalocyanine-based hole transporting material for perovskite solar cells with an open-circuit voltage above 1.0 V

The hole transporting materials for perovskite solar cells to increase power conversion efficiency ( PCE ) and improve the stability have been studied in recent years. In this paper, a novel asymmetric 2,9,16-triphenoxy-23-nitrophthalocyaninatocobalt (CoPcNO 2 -OPh) is synthesized, which can be employed as a promising hole transporting material in solid state perovskite solar cells. The three phenoxy groups introduced into phthalocyanine complex improved the solubility and inhibit the aggregation effectively. This material shows strong absorption and high thermal stability. The density functional theory (DFT) method of frontier molecular orbitals shows that the introduction of phenoxy and nitro can adjust the energy levels of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) to −5.14   eV and −3.05   eV respectively, indicating that CoPcNO 2 -OPh can be used as an hole transporting material. The optimized devices achieved a high open-circuit voltage of 1.04   V with a maximum power conversion efficiency of 8.24% under AM1.5   G standard conditions. The introduction of this new HTM offers a new and effective tool towards engineering the stability for large-scale applications.