Theoretical study on thienothiophene core hole-transporting materials in perovskite solar cells: S atom position effect

Hole-transporting materials (HTMs) play a critical role in realizing efficient and stabilizing perovskite solar cells (PSCs). Here, three molecules with different isomers of thienothiophene were investigated theoretically by controlling S atoms position on the thienothiophene-bridge. Consequently, the two electron-rich S atoms on the same side have a greater effect on the HOMO and the effective face-to-face stacking. Thus, TT-2,3-b-TPA exhibits more matched energy level, better optical properties, hole mobility and stability, and also shows better interfacial interactions and charge transfer capability at the HTM/perovskite interface, which may develop a potential HTMs instead of traditional spiro-OMeTAD.