The structural and electronic properties of mono and di-methyl substituted poly(p-phenylene benzobisthiazole) oligomers have been investigated theoretically employing quantum chemical calculations based on density functional theory (DFT) using the B3LYP functional. The neutral states geometries of these oligomers have been used to calculate the HOMO-LUMO gaps (D_H-L), ionization potentials (IP) and electron affinities (EA). The lowest excitation energies (E_g) and the maximum absorption spectra have been studied using the TDDFT/B3LYP/6-31G(D) method. The cationic and anionic states of these oligomers have been optimized using the same methodology. The optimized lowest singlet excited-state geometries of oligomers have been used to calculate the emission spectra by using TDDFT method. The D_H-Ls, IPs, EAs, E_gs, and absorption/emission spectra of the respective polymer have been obtained by extrapolating those of the oligomers to the inverse chain length equal to zero. From the reorganization energies, it can be seen that the electron transport energy values are smaller than the hole transport suggesting that these could be used as electron transport materials in light emitting diodes devices. Thus, these studies on the oligomers will help in rationalizing the properties of known polymers and to predict those of yet unknown ones for their utilization in electronic devices.

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单和二甲基取代的聚（对亚苯基苯并双噻唑）低聚物的结构和电子性质：计算研究

使用基于B3LYP官能团的基于密度泛函理论（DFT）的量子化学计算，从理论上研究了单和二甲基取代的聚（对苯撑苯并双噻唑）低聚物的结构和电子性质。这些低聚物的中性态几何形状已用于计算HOMO-LUMO间隙（D _H-L），电离电势（IP）和电子亲和力（EA）。最低激发能（E _g）和最大吸收光谱已使用TDDFT / B3LYP / 6-31G（D）方法进行了研究。这些低聚物的阳离子和阴离子状态已使用相同的方法进行了优化。优化的低聚物的最低单线激发态几何形状已通过TDDFT方法用于计算发射光谱。D _H-L s，IP，EA，E _gs，并且通过将低聚物的吸收/发射光谱外推至等于零的逆链长度获得了相应的聚合物的吸收/发射光谱。从重组能可以看出，电子传输能的值小于空穴传输能，表明它们可以用作发光二极管器件中的电子传输材料。因此，这些对低聚物的研究将有助于合理化已知聚合物的性能，并预测那些尚未未知的聚合物在电子设备中的用途。