Chain length dependence of singlet and triplet excited states of oligofluorenes: A density functional study
2007 (English)In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 336, no 2-3, 91-98 p.Article in journal (Refereed) Published
Using time dependent density functional theory, we investigate the chain length dependence of the energies of excited states of a series of conjugated 9,9-dihexylfluorene-2,7-diyl oligomers. Excited state optimization reveals that upon excitation the dihedral angle between two adjacent monomer units moves towards zero, forming a planar structure within the oligomer. The calculated energies of the optical transitions in absorption, fluorescence, phosphorescence and triplet-triplet absorption are compared with recently reported experimental data. The calculated as well as experimentally reported energies involved seem to saturate very fast as the chain length increases. The energy dispersion and saturation indicates that the triplet ground state is somewhat more confined than the first singlet excited state. Our calculated energies agree well with the experimental findings where available, showing small but systematic deviations.
Place, publisher, year, edition, pages
2007. Vol. 336, no 2-3, 91-98 p.
Chain length dependence, Excited states, Polyfluorene
IdentifiersURN: urn:nbn:se:kth:diva-26013DOI: 10.1016/j.chemphys.2007.05.021ISI: 000248780100001ScopusID: 2-s2.0-34447531765OAI: oai:DiVA.org:kth-26013DiVA: diva2:364565
QC 201011092010-11-092010-11-092010-12-03Bibliographically approved