A new binaphthol based hole-transporting materials for perovskite solar cells

A novel hole-transporting material (Q221) is synthesized by introducing benzyl groups onto the 1,1′-bi-2-naphthol central core as edge chains and bis(4-methoxyphenyl)amine-substituted 9H-carbazole as donor groups. A reference molecule (Q222) is prepared with hexyl edge chains. The introduction of edge chains influences their molecular orbital energy levels. Q221-based CH₃NH₃PbI₃ perovskite solar cells with carbon counter electrode exhibit the highest power conversion efficiency of 10.37% at a low doping level of Li-TFSI/TBP (15 mM/100 mM), and that of Q222-based cells is 8.87%. Q221-based cells doping with Li-TFSI/TBP of 15 mM/100 mM shows much better photovoltaic parameters compared to those doping with Li-TFSI/TBP of 30 mM/200 mM, when aged in ambient air of 30% RH without encapsulation. The new binaphthol based hole-transporting materials shows a great potential in fabricating effective perovskite solar cells.