Efficient strategies to improve photovoltaic performance of linear-shape molecules by introducing large planar aryls in molecular center and terminals

Three novel linear-shape small molecules of TPA(DPP–PN)2, Cz(DPP–PN)2 and Fl(DPP–PN)2 were synthesized and characterized, which contain the same arm of diketopyrrolopyrrole (DPP) and large aryl terminals of phenanthrene (PN), as well as different aryl centers of triphenylamine(TPA), carbazole (Cz) and fluorene (Fl), respectively. Narrower optical band gaps (1.62–1.69 eV) and lower highest occupied molecular orbital energy levels (−5.71 to −5.79...