Does the donor¨Cacceptor concept work for designing synthetic metals?

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• 作者：Ulrike Salzner ; Ozan Karalt? and Serdar Durda?i
• 关键词：Conducting polymers ; Donor– ; acceptor concept ; Band gap ; Band width ; Conductivity ; DFT
• 刊名：Journal of Molecular Modeling
• 出版年：2006
• 出版时间：July, 2006
• 年：2006
• 卷：12
• 期：5
• 页码：687-701
• 全文大小：282 KB

文摘

Homopolymers of quinoxaline (QX), benzothiadiazole (BT), benzobisthiadiazole (BBT), thienopyrazine (TP), thienothiadiazole (TT), and thienopyrazinothiadiazole (TTP) and copolymers of these acceptors with thiophene (TH) and pyrrole (PY) were investigated with density functional theory. Theoretical band-gap predictions reproduce experimental data well. For all but six copolymers, band-gap reductions with respect to either homopolymer are obtained. Four of the acceptors, BBT, TP, TT, and TTP, give rise to copolymers with band gaps that are smaller than that of polyacetylene. BBT and TTP copolymers with PY in 1:2 stoichiometry are predicted to be synthetic metals. Band-gap reductions result from upshifts of HOMO energies and much smaller upshifts of LUMO values. The smallest band gaps are predicted with TTP, since changes in LUMO energies upon copolymerization are particularly small. The consequence of the small interactions between LUMO levels of donor and acceptor are vanishingly small conduction bandwidths.