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Título: | Exciton diffusion in polyfluorene copolymer thin films : kinetics, energy disorder and thermally assisted hopping. |
Autor(es): | Dias, Fernando B. Kamtekar, Kiran T. Cazati, Thiago Williams, Geoff Bryce, Martin R. Monkman, Andrew P. |
Data do documento: | 2009 |
Referência: | DIAS, F. B. et al. Exciton diffusion in polyfluorene copolymer thin films: kinetics, energy disorder and thermally assisted hopping. ChemPhysChem, v. 10, p. 2096-2104, 2009. Disponível em: <http://onlinelibrary.wiley.com/doi/10.1002/cphc.200900112/epdf>. Acesso em: 10 mar. 2017. |
Resumo: | A series of {(9,9-dioctylfluorene)0.7x-(dibenzothiophene-S,S-di-oxide)0.3-[4,7-bis(2-thienyl)-2,1,3-benzothiadiazole]x}(PFS30-TB Tx),where x represents the minor percentage of the red emitter4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (TBT) randomly incor-porated into the copolymer backbon e, is investigated in orderto follow the energy transfer from PFS30to TBT moieties. Theemission of the donor poly[(9 ,9-dioctylfluorene)0.7-(dibenzothio-phene-S,S-dioxide)0.3identified by PFS30and peaking at450 nm, is clearly quenched by the presence of the red TBTchromophore emitting at 612 nm, with an isoemissive pointobserved when the spectra are collected as a function of tem-perature. A plot of the ratio between the TBT and PFS30emis-sions as a function of the reciprocal of temperature gives aclear linear trend between 290 and 200 K, with an activationenergy of 20 meV and showing a turn over to a non-activated egime below 200 K. Picosecond time-resolved fluorescencedecays collected at the PFS30and TBT emission wavelengths,show a decay of the PFS30emission and a fast build-in, fol-lowed by a decay, of the TBT emission, confirming that thepopulation of the TBT excited state occurs during the PFS30lifetime(~600 ps). The population of the TBT excited stateoccurs on a time regime around 150 ps at 290 K, showing anenergy barrier of 20 meV that turns over to a non-activatedregime below 200 K in clear agreement with the steady-statedata. The origin of the activation barrier is attributed to thepresence of physical and energetic disorder, affected by fastthermal fluctuations that dynamically change the energy land-scape and control the exciton migration through the polymerdensity of states. |
URI: | http://www.repositorio.ufop.br/handle/123456789/7351 |
Link para o artigo: | http://onlinelibrary.wiley.com/doi/10.1002/cphc.200900112/epdf |
DOI: | https://doi.org/10.1002/cphc.200900112 |
ISSN: | 1439-7641 |
Aparece nas coleções: | DEFIS - Artigos publicados em periódicos |
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ARTIGO_ExcitonDiffusionPolyfluorene.pdf Restricted Access | 342,58 kB | Adobe PDF | Visualizar/Abrir |
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