Theoretical Investigations on the Electronic and Optical Properties of Luminescent Poly(alkylthiophene-co-pyridine)

• 来源期刊: 中国化学（英文版）
• 年，卷（期）: 2007,（7）
• 页码范围: 898-905
• 页数: 8页
• 语种: 英文

摘要

Quantum-chemical techniques were applied to investigate a series of conjugated polymers: poly(3-octylthien2,5-ylene-co-pyrid-2,6-ylene) (p1), poly[pyrid-2,6-ylenebis(3-octylthien-2,5-ylene)] (p2) and poly[pyrid-2,5-ylenebis(3-octylthien-2,5-ylene)] (p3) comprising alternating π-excessive 3-alkylthiophene and π-deficient meta- or para-linked pyridine moieties. Their ground state and excited state structures were optimized with density functional theory B3LYP method, and the optical properties were calculated by the time-dependent density functional theory (TD-DFT) and ZINDO/S methods. Their HOMO-LUMO gaps (△H-L), the lowest excitation energies (Eex),ionization potentials (IP) and electron affinities (EA) were obtained by extrapolating those of the polymersto the inverse chain length equal to zero (1/n=0). The calculated results showed that the decrease of pyridylene content increased the HOMO level and decreased the LUMO level while the para-linkage further contributed to it. The IP are in the order: p1＞p2＞p3 but EA are: p1＜p2＜p3. In addition, the decrease of the pyridylene content and the para-linked pyridylene in the backbone of the polythiophene resulted in a narrowed energy gap and bathochromic absorption and emission peaks.