线型和星型平面噻吩类低聚物衍生物分子结构及光电性质研究

运用密度泛函DFT B3LYP／6-31G(d)方法对线型(a)和星型(b)平面噻吩类低聚物衍生物分别进行了几何构型优化,并采用含时密度泛函TD-DFT B3LYP／6-31G(d)方法计算了其紫外吸收光谱．计算结果表明:用TD-DFT．方法计算体系的紫外吸收光谱值与实验数据吻合;通过对噻吩类低聚物衍生物分子几何结构和前线分子轨道能级的分析,并从理论上解释了线型(a)和星型(b)衍生物光谱性质的差异:后者与前者相比较吸收光谱发生红移,这是由于星型结构使其相应HOMO能级升高,电离能(IP)降低,成为很好的电子给体和空穴传输材料．

Molecular structure and photo-electricity properties of liner and star-shaped planar oligothiophene derivatives

Liner (a) and star-shaped (b) oligothiophene derivatives were optimized using density functional theory (DFT) at B3LYP/6-31G(d) level. The UV absorption spectra of the corresponding compounds were also calculated using time-dependent density functional theory (TD-DFT) at the same level. The calculations showed that the UV absorption spectrum of the compounds calculated by TD-DFT method agrees well with the experimental data. Molecular geometric structures, the frontier molecular orbital energy levels and the electron cloud distributing rules of the oligothiophene derivatives have been analyzed We simultaneously interpreted the different photo-electricity properties of the derivatives. In comparison with linear compound (a), the absorption spectrum of star-shaped compound (b) shifts bathochromically, as the result of the increase of HOMO energy levels of (b) compound and the decrease of ionization potential, which make the star-shape oligothiophene derivatives become a good electron donor and hole transporting material.