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Ultrafast photoluminescence from Poly(p-phenylenevinylene)

University of British Columbia

Femtosecond time-resolved photoluminescence spectroscopy is used to study the dynamics of poly(p-phenylenevinylene) (PPV) at 77K and 300K over an energy range 2.19-2.37 eV. At all emission energies studied, the photoluminescence excited by ~100 fs long pulses of 400 nm radiation rises to a maximum value in less than 1 ps and then monotonically decreases with increasing delay. The decay curves can all be described by the summation of two, or in some cases three, exponential functions. Analysis of the spectral dependence of the various time constants extracted from these fits indicates that the photoluminescence at any given wavelength is due in general to the superposition of three transitions emanating from a single set of inhomogeneously broadened excitons. The three distinct transitions correspond to processes in which two, one or zero phonons are excited in the host polymer during the emission event. A complete analysis of the data indicates that the lifetime of the inhomogeneously broadened excitons is found to increase monotonically from a value less than the 300 fs time resolution of our system at 330 meV above the peak in the density of states (DOS), to 116 ps at an energy 7 meV below the peak in the DOS.

Thesis/Dissertation

application/pdf

2009-06-26

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http://hdl.handle.net/2429/9744

Physics

University of British Columbia

UBCV

DSpace