π桥中不同吸电子基团对三苯胺-氰基丙烯酸类染料敏化太阳能电池性能影响的理论研究

Different Electron-withdrawing Groups in π Spacers Effect on the Performance of Dye-sensitized Solar Cells Based on Triphenylamine-cyanoacrylic Acid Dyes

采用密度泛函理论和含时密度泛函理论计算了染料的紫外-可见吸收光谱、电子注入驱动力、半导体导带能级移动量以及染料与碘的相互作用能等一系列评价电池性能的理论参数,以解释在π桥上引入不同吸电子基团导致三苯胺-氰基丙烯酸基染料敏化太阳能电池光电转换效率降低的原因.结果表明,在染料π桥上引入吸电子基团虽可以在一定程度上改善吸收光谱,但同时也引入了额外的与电解质中碘相互作用的位点,加快了与电解质之间的复合速率,影响了电子注入驱动力,最终导致电池光电转换效率降低.因此,在设计高效光敏染料时除了考虑吸收光谱外,也应考虑染料与电解质之间的复合以及电子注入驱动力这2个影响电池性能的关键因素.

We performed this work in order to rationalize the negative effect of introducing different electronwithdrawing groups in phenylene-based π-spacers on the performance of dye-sensitized solar cells based on five organic dyes consisting of triphenylamine as donor and cyanoacrylic acid as acceptor. UV-absorption spectrum, the electron injection driving force, the shift of the conduction band energy level and the interaction energy of dye-I2 and so on, were carried out with density functional theory （DFT） and time-dependent DFT, which are associated with the performance of cell. The results reveal that charge recombination between injected electrons and iodine as well as the electron injection driving force limit the open-circuit photovohage and the short-circuit current density, respectively, eventually led to the reduce of conversion efficiency. Therefore, in design and development more efficient dyes in future, except for considering the absorption spectrum, the interaction between dyes and I2and the electron injection efficiency should be taken into account as the critical factors for the efficiency of dye-sensitized solar cell（DSSC）.