The electronic states of polyfluorene copolymers with alternating donor-acceptor units

被引:271
作者
Jespersen, KG
Beenken, WJD
Zaushitsyn, Y
Yartsev, A
Andersson, M
Pullerits, T
Sundström, V
机构
[1] Lund Univ, Kemicentrum, Dept Chem Phys, SE-22100 Lund, Sweden
[2] Univ Vienna, Inst Theoret Phys, A-1090 Vienna, Austria
[3] Chalmers Univ Technol, Dept Mat & Surface Chem Polymer Technol, SE-41296 Gothenburg, Sweden
关键词
D O I
10.1063/1.1817873
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We calculate the electronic states of the low bandgap polyfluorene-based copolymer DiO-PFDTBT, which consists of alternating 9,9-dioctyl-9H-fluorene and 4,7-di-thiophen-2-ylbenzo[1,2,5]thiadiazole (TBT) units, and compare with the steady-state absorption, emission, and excitation spectrum. Using the semiempirical quantum-chemical (ZINDO) method we can assign the characteristic bands of the "camel-back" absorption spectrum to one charge transfer state at lower energy localized on the TBT unit, and one delocalized excitonic state at higher energy corresponding to the pi-conjugated electron system. Additional "dark" charge transfer states in the gap between these bands have been revealed. Calculations are also made on the red light emitting polyfluorene-based copolymer poly(fluorene-co-benzothiadiazole) (F8BT), which contains benzo[1,2,5]thiadiazole instead of TBT. The nature of the electronic states in F8BT and DiO-PFDTBT are found to be qualitatively the same. (C) 2004 American Institute of Physics.
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页码:12613 / 12617
页数:5
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