半菁染料作为染料敏化太阳能电池吸光材料的理论研究（英文）

Theoretical Study of Hemicyanine Dye as a Dye-Sensitized Solar Cell Light-Absorbing Material

采用第一性原理研究了半菁-二氧化钛团簇形成的配合物(hemicyanine-(Ti O2)n)的光电子转移过程,这里n分别取5,9,15.配合物基态构型采用密度泛函理论方法进行优化,而激发态采用含时密度泛函理论进行计算.采用长程相关校正的密度泛函CAM-B3LYP和ωB97X-D计算的激发能与实验值吻合得很好.依据广义Mulliken-Hush(GMH)公式,基于密度泛函理论得到的波函数被用来计算电荷转移积分,进而可根据Marcus理论计算出电荷分离速率常数(kCS)和电荷回传速率常数(kCR).计算结果表明电子从染料到(Ti O2)n团簇的传递有多条通道,这使得kCS具有更大值,相反,只具有单通道的电荷回传降低了kCR值,与kCS相比甚至可以忽略,这表明在所研究的体系中电荷回传是不利的.

We used first- principles calculations to investigate the photo- induced electron transfer（PIET）process of the hemicyanine-（Ti O2）ncomplex（（Ti O2）n-dye） for n=5, 9, 15. The geometries of the（Ti O2）n-dye in the ground state were optimized using density functional theory（DFT） and their excited states were investigated using the time-dependent DFT（TDDFT） method. The excited energies, which were calculated using the longrange-corrected functionals, CAM-B3 LYP and ωB97X-D, were in good agreement with the experimentally observed values. The wave functions based on DFT were used to calculate the charge transfer integrals by the generalized Mulliken-Hush（GMH） approach. In addition, the photo-induced charge separation rate constant（kCS） and charge recombination rate constant（kCR） were calculated using Marcus theory. The calculated results showed that there were a cascade of electron transfer channels from the dye into the（Ti O2）ncluster, which increases the kCSvalue. In contrast, the single channel of charge recombination decreases the kCRvalue, which is negligible compared with kCS, indicating that electron recombination is not favored.