Facile synthesis of simple arylamine-substituted naphthalene derivatives as hole-transporting materials for efficient and stable perovskite solar cells

Massive efforts are devoted to exploring alternative hole-transporting materials for efficient and stable perovskite solar cells. As one typical polycyclic aromatic hydrocarbon, naphthalene group endows a favorable planar conformation and further extended pi-conjugation, both of which accelerate the process of hole extraction and transport. In this work, two small molecule hole-transporting materials based on naphthalene core and arylamine terminal groups, termed NH-2,6 and NH-2,7, are prepared via facile synthesis from commercial precursors with a low synthetic cost. NH-2,6, which incorporates particular 2,6-substituted naphthalene core and arylamine terminal, exhibits a deeper highest occupied molecular orbital and a higher hole mobility ascribing to the discriminating structural substitution position effect and better electronic delocalization extent between naphthalene core and arylamine terminal. Thus with NH-2,6, impressive efficiency of 18.7%, which is associated with excellent reproducibility and reasonable stability, is afforded based on the optimized mixed cation perovskite solar cells. These results not only highlights that the properties of hole-transporting materials can be tuned to some extent through the substitution position effect, but also provides the significative insights into the molecule design for facile synthesis, low-cost and efficient hole-transporting materials.