Photoluminescence Spectra Of Conjugated Polymers With Nondegenerate Ground-State

TitlePhotoluminescence Spectra Of Conjugated Polymers With Nondegenerate Ground-State
Publication TypeJournal Article
Year of Publication1991
AuthorsMcKenzie, Ross H., and Wilkins J. W.
JournalSynthetic Metals
AbstractPhotoluminescence is observed in conjugated polymers with nondegenerate ground states such as cis-polyacetylene, polythiophene (PT), and polyphenylenevinylene (PPV). The spectrum of emitted light exhibits vibronic structure, i.e., a series of discrete peaks separated by optic phonon frequencies. To model this, we consider the lattice relaxation (multiple phonon emission) associated with radiative recombination of polaron-excitons, treating them as a confined soliton-antisoliton pair. The emission spectrum is calculated using the Brazovskii-Kirova continuum model and the formalism developed by Su and Yu to describe lattice relaxation in conjugated polymers. We find that the number of phonon peaks in the emission spectrum depends sensitively on the confinement parameter-gamma. Agreement of the observed emission spectra for polythiophene with the calculated spectrum requires that gamma approximately 1, a value much larger than previous estimates of gamma, which have been in the range 0.1 to 0.3.