Chalcogen-Containing Hole Transporting Materials

Abstract

Abstract This review summarizes our recent achievements in the development of new chalcogen-containing materials employed as hole-transporting materials (HTMs) in efficient perovskite solar cells (PSCs). Following a simple and inexpensive synthetic methodology we prepared new heterocycle-based HTMs with comparable photovoltaic (PV) behaviour to the widely used spiro-OMeTAD. In particular, new star-shaped HTMs have been obtained through an easy synthetic route by crosslinking electron-donor groups with a central scaffold. As sulfur-containing cores, benzo[1,2-b:3,4-b′:5,6-b′′]trithiophene (BTT) and the corresponding isomers (bbb-BTT and bbc-BTT), thieno[3,2-b]thiophene (TbT), cyclooctatetrathiophene (CoTh), anthra[1,2-b:4,3-b′:5,6-b′′:8,7-b′′′]tetrathiophene (ATT), dibenzothieno[1,2-b:4,3-b′:6,7-b′′:9,8-b′′′]quinquethiophene (DBQT), dibenzothieno[3,2-b]thiophen[1,2-b:4,3-b′:6,7-b′′:9,8-b′′′]sexithiophene (DBST) and thioxanthone have been employed. To extend the comparison, HTMs with heteroatoms such as oxygen or selenium in the central unit, namely xanthone (BX), benzotrifuran (BTF) or benzotriselenophene (BTSe), were also designed, synthesized and employed in PSCs. Currently, there is no doubt that organic compounds are an important part of the PSCs architecture. Nevertheless, the future commercialization of PSCs is driven by the development of HTMs away from the comprehension of structure-property relationships. Therefore, our main goal is to contribute to a better understanding of the chemistry behind competitive HTMs and provide a clear picture of the effect of chalcogen-containing HTMs in device performances.