Diaryl ketone-based hole-transporting materials for efficient perovskite solar cells

In this work, for the first time benzophenone and dipyridyl ketone were introduced as the core structure to synthesize two new D-A-D type molecules, namely BP-DC and PT-DC, and they were applied as hole transport materials in conventional perovskite solar cells. TGA and DSC show excellent thermal stability of both materials. Cyclic voltammetry measurements indicate that the energy levels of the two new materials match well with the valence band of perovskite materials. Compared to the benzophenone-cored BP-DC, the central dipyridyl ketone unit in PT-DC brings about stronger molecular interaction and better film quality. Moreover, PT-DC shows higher hole mobility than BP-DC. Photoluminescence quenching at the perovskite/PT-DC interface is more effective than that at the perovskite/BP-DC interface. Consequently, the PT-DC-based devices achieve a high efficiency of 18.27% with negligible hysteresis effect, higher than the performance of the BP-DC-based device (16.70%).