Synthesis, Characterization, and Properties of Homopolymers Functionalized with Oligothiophene Derivatives in the Side Chain

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• 作者：Chunchang Zhao ; Yong Zhang ; Shanlin Pan ; Lewis Rothberg ; Man-Kit Ng
• 刊名：Macromolecules
• 出版年：2007
• 出版时间：March 20, 2007
• 年：2007
• 卷：40
• 期：6
• 页码：1816 - 1823
• 全文大小：197K
• 年卷期：v.40,no.6(March 20, 2007)
• ISSN：1520-5835

文摘

Two novel polynorbornenes 11 and 12 functionalized with electronically active conjugated oligomerunits in the side chain were synthesized by the ring-opening metathesis polymerization (ROMP) method. Bothpolymers showed good optical characteristics, thermal stability, film-forming properties, and interestingelectrochemical properties. The photophysical and redox behaviors of 11 and 12 are markedly different due tovariation in the structure of the pendant oligomers. Polymer 11 with phenyl end-capped oligothiophene co-oligomer in the side chain showed much higher stability toward electrochemical oxidation than 12 with asexithiophene in the side chain. This was demonstrated by in-situ study of the changes in absorption spectra ofthe polymer films while varying the potential in electrochemical experiments. During the p-doping process, polymer11 exhibited highly reversible changes in its absorption peaks when monitored at 430 and 650 nm, and thep-doping/dedoping processes can be repeated many cycles. In sharp contrast, polymer 12 was shown to beelectrochemically unstable under the same conditions. Single-layer photovoltaic cells have been fabricated with11 or 12 as the active organic layer, and their relative performances were compared. These single-layer devicesshowed relatively large open-circuit voltage and moderate short-circuit current. In addition, the solar cell fabricatedfrom 11 showed better device stability under ambient conditions than that from 12, which can be attributed to thehigher stability of phenyl end-capped oligothiophene co-oligomer compared to that of the sexithiophene.