Thickness Dependence of the Fluorescence Lifetime in Films of Bisfluorene-Cored Dendrimers
The effect of film thickness on fluorescence lifetime, quantum yield, and exciton diffusivity is studied in first-generation bisfluorene-cored dendrimers with E-stilbenyl and biphenyl-based dendrons. A decrease of the fluorescence lifetime and quantum yield is observed in films thinner than 50 nm sp...
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Published in | Journal of physical chemistry. C Vol. 112; no. 51; pp. 20463 - 20468 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
American Chemical Society
25.12.2008
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Subjects | |
Online Access | Get full text |
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Summary: | The effect of film thickness on fluorescence lifetime, quantum yield, and exciton diffusivity is studied in first-generation bisfluorene-cored dendrimers with E-stilbenyl and biphenyl-based dendrons. A decrease of the fluorescence lifetime and quantum yield is observed in films thinner than 50 nm spin-coated on fused silica substrates. The radiative decay of the singlet excited-state and singlet exciton diffusion rates are independent of the film thickness within a 20% uncertainty. The fluorescence lifetime of dendrimers dispersed in an inert host is also independent of film thickness. The nonradiative decay rate increases by a factor of 4 in thin films of dendrimers with first-generation E-stilbenyl dendrons. The same effect is observed on different glass and sapphire substrates, and it is much weaker in the dendrimer with first-generation biphenyl dendrons, which allows us to rule out quenching by substrate. The data can be explained by long-range (dipole−dipole) energy transfer to quenching sites concentrated at the surface of thin films. The results contribute to understanding of the thin film photophysics and will help development of light-emitting devices. |
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Bibliography: | ark:/67375/TPS-9ZB7PRT3-S istex:92AC08FB90A415759A2D9D036D3E541AA6F2E554 |
ISSN: | 1932-7447 1932-7455 |
DOI: | 10.1021/jp805429d |