中文摘要：

应用密度泛函理论（DFT）方法计算[6,6]-苯基-C61-丁酸甲酯（PCBM）及其苯环对位取代得到的4种衍生物的几何和电子结构.采用第一激发能校正了分子的最低未占据分子轨道（LUMO）能级,探讨了推/拉电子基团对分子前线轨道的影响.在全优化几何构型的基础上,采用含时密度泛函理论（TD-DFT）方法研究了电子吸收光谱特征和电荷转移态性质,并讨论了推/拉电子基团对体系电子吸收光谱性质的影响.通过对重组能和电子亲和势的计算,预测了PCBM与4种衍生物的电子能力及电子迁移率大小的关系.结果表明,在PCBM中,在苯环的对位引入推电子基团可以提高分子的前线轨道能级,改变前线轨道电子云分布,明显增强可见光范围内的吸收强度,增加可见光范围内的电荷转移吸收,且激发态的电荷转移随着引入基团推电子能力的增加而增强.化合物5的激发态分子内电荷转移性质最强,且具有较独特的光伏性质.而在同样位置引入拉电子基团,则降低了分子前线轨道能级对电子吸收光谱的影响.

英文摘要：

The geometric and electronic properties of -phenyl-C61-butyric acid methyl ester（PCBM） and its four new derivatives,with electron-donating and electron-withdrawing group on p-position of phenyl ring,as electron acceptor materials in bulk heterojunction organic solar cell were studied by density functional theory（DFT）.The influences of substituent on frontier molecular orbitals were investigated by the corrected lowest unoccupied molecular oribital（LUMO） energy with the lowest excitation energy.UV-Vis spectrum properties and electron states were investigated by time-depended density functional theory（TD-DFT） on the basis of the ground state geometry.Furthermore,we also calculated the electron reorganization energy and electron affinity energy to predict the electron mobility of the five compounds.The results indicate that the electron-donating substituents introduced on the phenyl ring of PCBM will improve the LUMO energy and enhance the absorption strength of visible region of the UV-Vis spectrum.Particularly,the compound 5 has the most excellent charge transfer property of all the compounds.There are no significant changes while introducing electron-withdrawing substituent groups on the same position in PCBM.