Tetrathiafulvalene derivative as a new hole-transporting material for highly efficient perovskite solar cell

Hole-transporting materials play an important role in perovskite solar cells. In this study, we introduced a novel hole-transporting material without p-type dopant, a tetrathiafulvalene derivative anchored with eight carboxyl groups (TTA) into inverted structure perovskite solar cells. The devices with TTA as hole-transporting layer showed high power conversion efficiency of 16.7%, which was 44.5% improvement compared with the reference devices without hole-transporting layer. The performance improvement was ascribed to three factors: 1) the better match of energy level between ITO and perovskite layer; 2) enhanced hole extraction at anode interface; 3) improved perovskite morphology.