Anthradithiophene based hole-transport material for efficient and stable perovskite solar cells

A novel hole-transport material (HTM) based on an anthradithiophene central bridge named BTPA-7 is developed. In comparison to spiro-OMeTAD (2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene), the synthetic steps of BTPA-7 are greatly reduced from 6 to 3 and the synthetic cost of BTPA-7 is nearly a half that of spiro-OMeTAD. Moreover, BTPA-7 exhibits a relatively lower conductivity but higher hole mobility and higher glass transition temperature (Tg) than spiro-OMeTAD. Compared with the photovolatic performance for spiro-OMeTAD, FA0.85MA0.15PbI3 and MAPbI3 PSC devices based on BTPA-7 exhibit slightly lower PCEs with the values of 17.58% (18.88% for spiro-OMeTAD) and 11.90% (13.25% for spiro-OMeTAD), respectively. Nevertheless, a dramatically higher Jsc of PSC based on BTPA-7 is achieved, which arises from the higher hole mobility of BTPA-7. In addition, the relatively hydrophobic character of BTPA-7 eventually enhances the PSC device stability. Lower cost, higher hole mobility, higher Tg, satisfactory photovoltaic performance, and superior device stability of BTPA-7 can be utilized as a substitute for spiro-OMeTAD in PSCs.