Synthesis and Characterizations of Poly(9,10-bisarylethynyl-2,6-anthrylene)s and Poly(9,10-bisalkynyl-2,6-anthrylene)

A poly(9,10-bisalkynyl-2,6-anthrylene) (PI) and five poly(9,10-bisarylethynyl-2,6-anthrylene)s(P2-P6) as soluble conjugated polymers have been synthesized and characterized. All polymers exhibit two-dimensional conjugated characteristics as indicated by absorption spectra comprising multi-bands in the range of 300-600 nm. Compared with P1, polymers P2-P5, which contain phenylethynyl substituents with the longer conjugation than alkynyl groups, exhibit a similar to 60 nm red shift of absorption edge. However, further increasing the conjugation length of the arylethynyl substituents (longer than phenylethynyl) has only a no effect on the conjugation of the polymer chains, while comparing the absorption spectra of P6 with those of P2-P5. All polymers show absorption spectra with a noticeable red shift from solutions to films, indicative of stronger intermolecular interaction in solid state. The highest occupied molecular orbital (HOMO) energy levels are -5 32 eV for P1 and around -5 20 eV for phenylethynyl-substituted polymers. Bulk heterojunction polymer solar cells (PSCs) of the polymers were fabricated with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as the acceptor material. Polymer PI exhibits the highest power conversion efficiency (PCE) of 1.60% with an open-circuit voltage (V-oc) of 0.96 V, a short-circuit current density (J(sc)) of 3.18 mA/cm(2), and a fill factor (FF) of 0.53.