Bodedla Govardhana Babu, Thomas K R Justin, Fan Miao-Syuan, Ho Kuo-Chuan
Organic Materials Chemistry, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
Department of Chemical Engineering, National Taiwan University, Taipei, 10617, Taiwan.
Chem Asian J. 2016 Sep 20;11(18):2564-77. doi: 10.1002/asia.201600766. Epub 2016 Sep 5.
Benzimidazole-branched bi-anchoring organic dyes that contained triphenylamine/phenothiazine donors, 2-cyanoacrylic acid acceptors, and various π linkers were synthesized and examined as sensitizers for dye-sensitized solar cells. The structure-activity relationships in these dyes were systematically investigated by using absorption spectroscopy, cyclic voltammetry, and density functional theory calculations. The wavelength of the absorption peak was more-heavily influenced by the nature of the π linker than by the nature of the donor. For a given donor, the absorption maximum (λmax ) was red-shifted on changing the π linker from phenyl to 2,2'-bithiophene, whilst the dyes that contained triphenylamine units displayed higher molar extinction coefficients (ϵ) than their analogous phenothiazine-based triphenylamine dyes, which led to good light-harvesting properties in the triphenylamine-based dyes. Electrochemical data for the dyes indicated that the triphenylamine-based dyes possessed relatively low-lying HOMOs, which could be beneficial for suppressing back electron transfer from the conduction band of TiO2 to the oxidized dyes, owing to facile regeneration of the oxidized dye by the electrolyte. The best performance in the DSSCs was observed for a dye that possessed a triphenylamine donor and 2,2'-bithiophene π linkers. Electron impedance spectroscopy (EIS) studies revealed that the use of triphenylamine as the donor and phenyl or 2,2'-bithiophene as the π linkers was beneficial for disrupting the dark current and charge-recombination kinetics, which led to a long electron lifetime of the injected electrons in the conduction band of TiO2 .
合成了含有三苯胺/吩噻嗪供体、2-氰基丙烯酸受体和各种π连接基的苯并咪唑支化双锚定有机染料，并将其作为染料敏化太阳能电池的敏化剂进行了研究。通过吸收光谱、循环伏安法和密度泛函理论计算，系统地研究了这些染料的构效关系。吸收峰的波长受π连接基性质的影响比供体性质的影响更大。对于给定的供体，将π连接基从苯基改变为2,2'-联噻吩时，最大吸收波长（λmax）发生红移，而含有三苯胺单元的染料比其类似的基于吩噻嗪的三苯胺染料表现出更高的摩尔消光系数（ϵ），这使得基于三苯胺的染料具有良好的光捕获性能。染料的电化学数据表明，基于三苯胺的染料具有相对较低的最高占据分子轨道（HOMO），这有利于抑制从TiO2导带向氧化染料的背向电子转移，因为氧化染料可通过电解质轻松再生。对于具有三苯胺供体和2,2'-联噻吩π连接基的染料，在染料敏化太阳能电池中观察到了最佳性能。电子阻抗谱（EIS）研究表明，使用三苯胺作为供体，苯基或2,2'-联噻吩作为π连接基有利于破坏暗电流和电荷复合动力学，这导致注入到TiO2导带中的电子具有较长寿命。
