Stable and efficient hole transporting materials with a dimethylfluorenylamino moiety for perovskite solar cells.

Novel star-shaped hole transporting materials (HTMs) with a bis-dimethylfluorenylamino moiety have been synthesized and evaluated for high performance perovskite solar cell applications. Maximum power conversion efficiency of 14.21% has been achieved by using the HTM with a fused TPA core and the long-term stability was also shown to be comparable with that of spiro-OMeTAD.