Synthesis and Characterizations of Poly(9,10-bisarylethynyl-2,6-anthrylene)s and Poly(9,10-bisalkynyl-2,6-anthrylene)
journal contributionposted on 10.11.2009, 00:00 by Weibin Cui, Yun Zhao, Hongkun Tian, Zhiyuan Xie, Yanhou Geng, Fosong Wang
A poly(9,10-bisalkynyl-2,6-anthrylene) (P1) 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 multibands 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 ∼60 nm red shift of absorption edge. However, further increasing the conjugation length of the arylethynyl substituents (longer than phenylethynyl) has only a negligible 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 P1 exhibits the highest power conversion efficiency (PCE) of 1.60% with an open-circuit voltage (Voc) of 0.96 V, a short-circuit current density (Jsc) of 3.18 mA/cm2, and a fill factor (FF) of 0.53.