Origin of spectral broadening in pi-conjugated amorphous semiconductors

Lupton, J. M., Samuel, I. D. W. and Burn, P. L. (2002) Origin of spectral broadening in pi-conjugated amorphous semiconductors. Physical review. B, Condensed matter and materials physics, 66 15: 155206-1-155206-6. doi:10.1103/PhysRevB.66.155206

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Author Lupton, J. M.
Samuel, I. D. W.
Burn, P. L.
Title Origin of spectral broadening in pi-conjugated amorphous semiconductors
Journal name Physical review. B, Condensed matter and materials physics   Check publisher's open access policy
ISSN 1098-0121
0163-1829
1550-235X
Publication date 2002-01-01
Sub-type Article (original research)
DOI 10.1103/PhysRevB.66.155206
Open Access Status File (Publisher version)
Volume 66
Issue 15
Start page 155206-1
End page 155206-6
Total pages 6
Place of publication New York
Publisher American Physical Society
Language eng
Subject 02 Physical Sciences
Abstract We present a study of the picosecond fluorescence dynamics of pi-conjugated semiconducting organic dendrimers in the solid state. By varying the degree of branching within the dendrons, referred to as the dendrimer generation, a control of intermolecular spacing of the emissive core and therefore of the lattice parameter for Forster-type energy transfer is achieved. This allows a distinction between spectral diffusion and excimer formation as the two main sources of spectral broadening in organic semiconductors. Whereas Forster-type dispersive spectral relaxation is independent of temperature but strongly dependent on the interchromophore distance, excimer formation is also strongly thermally activated due to temperature-dependent conformational changes and the influence of thermally activated dynamic disorder. The rapid spectral diffusion allows a determination of the excimer rise in the emission, which is shown to have a profound impact on the steady state luminescence properties of dendrimer films. We show that the dendrimer generation not only allows a microscopic control of intermolecular interactions but also a direct control of the rate of spectral diffusion. Implications for the design of novel materials for optoelectronic devices are discussed.
Keyword Physics, Condensed Matter
Monte-carlo Simulations
Fluorescence Dynamics
Dendrimer Generation
Relaxation Dynamics
Polyfluorene Film
Polymers
Photoluminescence
Photoexcitations
Luminescence
Excitations
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

 
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Created: Thu, 20 Sep 2007, 01:46:12 EST