Qin, PengKast, HanneloreNazeeruddin, Mohammad K.Zakeeruddin, Shaik M.Mishra, AmareshBaeuerle, PeterGraetzel, Michael2014-10-232014-10-232014-10-23201410.1039/c4ee01220hhttps://infoscience.epfl.ch/handle/20.500.14299/107738WOS:000340450100016Novel low band gap oligothiophenes incorporating S,N-heteropentacene central units were developed and used as hole-transport materials (HTMs) in solid-state perovskite-based solar cells. In addition to appropriate electronic energy levels, these materials show high photo-absorptivity in the low energy region, and thus can contribute to the light harvesting of the solar spectrum. Solution-processed CH3NH3PbI3-based devices using these HTMs achieved power conversion efficiencies of 9.5-10.5% in comparison with 7.6% obtained by reference devices without HTMs. Photoinduced absorption spectroscopy gave further insight into the charge transfer behavior between photoexcited perovskites and the HTMs.text::journal::journal article::research article