Dibenzo[b,d]thiophene 5,5-dioxide-based dopant-free hole-transporting material with passivation effect in inverted perovskite solar cells

For the rocket development of organic -inorganic hybrid perovskite solar cells (OIH-PSCs), the research of lowcost, dopant-free hole -transporting materials (HTMs) with high performance and stability is still an urgent problem. In this work, we synthesize organic small molecule HTM with sulfone-containing benzodithiophene (BDTOxide) as the central unit, termed BDTOxide-MTP. The synthetic cost of DBTOxide-MTP in the lab is 238 CNY/g, which is just one -fifth of the cost of the PTAA (1200 CNY/g). BDTOxide-MTP exhibits the deep highest occupied molecular orbital energy level, high hole transport mobility, and excellent passivation effect. BDTOxide-MTP is introduced into inverted OIH-PSCs as a dopant-free hole transport layer, the champion efficiency of MAPbI3-xClx-based devices reaches 18.72 % with an excellent VOC of 1.13 V, while the efficiency of the control device based on PTAA is about 18.49 %. The device based on BDTOxide-MTP exhibits comparable stability to the one based on PTAA, which can maintain over 90 % of the original efficiency after 46 days in a nitrogen environment.