Fluorine-substituted benzothiadiazole-based hole transport materials for highly efficient planar perovskite solar cells with a FF exceeding 80.

Fluorine-substituted benzothiadiazole (BT) was introduced as a core structure to construct new hole transport materials. Planar perovskite solar cells with conventional materials (CH3NH3PbI3-xClx) were fabricated. The perovskite solar cells using monofluorinated BT exhibit a leading efficiency of 18.54% with a FF as high as 81%.