Carbazole-based sensitizers for potential application to dye sensitized solar cells
作者:NARESH DUVVA、RAVI KUMAR KANAPARTHI、JAIPAL KANDHADI、GABRIELE MAROTTA、PAOLO SALVATORI、FILIPPO DE ANGELIS、LINGAMALLU GIRIBABU
DOI:10.1007/s12039-015-0794-1
日期:2015.3
Two push-pull molecules employing carbazole and alkyl thiophene (CAR-THIOHX) or carbazole and triphenylamine (CAR-TPA) as donor moieties, with the cyanoacrylic group as the acceptor, have been designed and synthesized by simple organic transformations. Photophysical and electrochemical studies revealed the potential of these two systems in dye sensitized solar cells (DSSC). Under standard irradiation conditions, CAR-TPA and CAR-THIOHX exhibited 2.12 and 1.83% of overall power conversion efficiencies respectively. The moderate photovoltaic efficiency of the sensitizers has been attributed to the poor light absorption of the sensitizers in the visible region. Density functional theory (DFT) calculations have shown a strong intramolecular charge transfer character, with the HOMOs of both the sensitizers exclusively localized on the corresponding donor moieties and LUMOs on the cyanoacrylic acid acceptor. On the other hand, the calculated high dihedral angle between the carbazole donor and the phenyl bridge for these sensitizers impedes the conjugation along the dyes backbone, and thus leads to less extended and intense absorption spectra in the visible region.
通过简单的有机转化,设计并合成了以咔唑和烷基噻吩(CAR-THIOHX)或咔唑和三苯胺(CAR-TPA)为供体分子,以氰基丙烯酸基团为受体的两种推拉分子。光物理和电化学研究揭示了这两种体系在染料敏化太阳能电池(DSSC)中的应用潜力。在标准照射条件下,CAR-TPA 和 CAR-THIOHX 的总功率转换效率分别为 2.12% 和 1.83%。敏化剂的光电转换效率较低的原因是敏化剂在可见光区域的光吸收较差。密度泛函理论(DFT)计算表明,两种敏化剂都具有很强的分子内电荷转移特性,其 HOMOs 完全定位于相应的供体分子,而 LUMOs 则定位于氰基丙烯酸受体。另一方面,计算得出的这些敏化剂的咔唑供体与苯桥之间的高二面角阻碍了沿染料骨架的共轭,从而导致在可见光区域的吸收光谱不那么延伸和强烈。