Thompson Barry C, Kim Young-Gi, McCarley Tracy D, Reynolds John R
George and Josephine Butler Polymer Research Laboratory and Center for Macromolecular Science and Engineering, Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA.
J Am Chem Soc. 2006 Oct 4;128(39):12714-25. doi: 10.1021/ja061274a.
A family of soluble narrow band gap donor-acceptor conjugated polymers based on dioxythiophenes and cyanovinylenes is reported. The polymers were synthesized using Knoevenagel polycondensation or Yamamoto coupling polymerizations to yield polymers with molecular weights on the order of 10 000-20 000 g/mol, which possess solubility in common organic solvents. Thin film optical measurements revealed narrow band gaps of 1.5-1.8 eV, which gives the polymers a strong overlap of the solar spectrum. The energetic positions of the band edges were determined by cyclic voltammetry and differential pulse voltammetry and demonstrate that the polymers are both air stable and show a strong propensity for photoinduced charge transfer to fullerene acceptors. Such measurements also suggest that the polymers can be both p- and n-type doped, which is supported by spectroelectrochemical results. These polymers have been investigated as electron donors in photovoltaic devices in combination with PCBM ([6,6]-phenyl C(61)-butyric acid methyl ester) as an electron acceptor based on the near ideal band structures designed into the polymers. Efficiencies as high as 0.2% (AM1.5) with short circuit current densities as high as 1.2-1.3 mA/cm(2) have been observed in polymer/PCBM (1:4 by weight) devices and external quantum efficiencies of more than 10% have been observed at wavelengths longer than 600 nm. The electrochromic properties of the narrow band gap polymers are also of interest as the polymers show three accessible color states changing from an absorptive blue or purple in the neutral state to a transmissive sky-blue or gray in the oxidized and reduced forms. The wide electrochemical range of electrochromic activity coupled with the strong observed changes in transmissivity between oxidation states makes these materials potentially interesting for application to electrochromic displays.
报道了一类基于二氧噻吩和氰基亚乙烯基的可溶性窄带隙供体-受体共轭聚合物。这些聚合物通过克诺文纳格尔缩聚或山本偶联聚合反应合成，得到分子量约为10000-20000 g/mol的聚合物，它们在常见有机溶剂中具有溶解性。薄膜光学测量显示其窄带隙为1.5-1.8 eV，这使得聚合物与太阳光谱有很强的重叠。通过循环伏安法和差分脉冲伏安法确定了能带边缘的能量位置，表明这些聚合物在空气中稳定，并且显示出向富勒烯受体进行光诱导电荷转移的强烈倾向。此类测量还表明这些聚合物可以进行p型和n型掺杂，光谱电化学结果也支持了这一点。基于聚合物中设计的近乎理想的能带结构，这些聚合物已被研究用作光伏器件中的电子供体，与作为电子受体的PCBM（[6,6]-苯基C(61)-丁酸甲酯）相结合。在聚合物/PCBM（重量比1:4）器件中观察到高达0.2%（AM1.5）的效率，短路电流密度高达1.2-1.3 mA/cm²，并且在波长大于600 nm时观察到超过10%的外量子效率。窄带隙聚合物的电致变色特性也备受关注，因为这些聚合物显示出三种可及的颜色状态，从中性状态下吸收性的蓝色或紫色变为氧化态和还原态下透射性的天蓝色或灰色。电致变色活性的宽电化学范围以及氧化态之间观察到的强透射率变化使得这些材料在电致变色显示器应用方面具有潜在的吸引力。
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