新型低带隙聚合物结构和性质的理论研究

Abstract

In this work, A series of novel co-polymers which are obtained by combining 3,4-vinylene- dioxythiophene(VDOT) with thieno[3,4-b]pyrazine(TP), furo[3,4-b]pyrazine(FP) and 6H-Pyrrolo[3,4-b]pyrazine(PP) are prepared. The structures and electronic properties of those polymers as well as their corresponding monomers and oligomers are studied by the density function theory (DFT) at B3LYP level with 6-31G * . The change of the bond lengths, bond critical point (BCP) properties, Wiberg bond index (WBIs) and nucleus-independent chemical shift (NICS) show that the conjugational degree is increased with main chain extension. To understand the effect of the ratio of VDOT to TP, FP and PP unit (V-P ratio) for electronic properties of investigated compounds, those compounds with the V-P ratio of 1:1, 1:2 and 2:1 are analyzed. The results show that the conjugational degree of oligomers with 1:2 V-P ratio is the best and that of oligomers with 2:1 V-P ratio is the worst. The small electron-transfer reorganization energy indicates polymers with 1:2 and 2:1 V-P ratio may be potential electron transport materials. The band structure analysis shows that all of polymers with 1:1 V-P ratio which include (VDOT-TP) n , (VDOT-FP) n and (VDOT-TP) n have relatively narrow band gap and very large bandwidth. Therefore, those polymers can be considered as potential organic conductive materials. In addition, (VDOT-BTP) n and (VDOT-BFP) n have quite low band gap (0.73 and 0.87 eV, respectively) and suitable bandwidth which indicate that they may be good intrinsic conductors.