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Publication details for Professor Andy Monkman
Feller, F & Monkman, AP (2000). Optical spectroscopy of oriented films of poly (2,5-pyridinediyl). Physical Review B 61(20): 13560-13564.- Publication type: Journal papers: academic
- ISSN/ISBN: 0163-1829
- Keywords: CONJUGATED POLYMERS; ELECTROABSORPTION
Author(s) from Durham
Abstract
Absorption and electroabsorption measurements on (stretched) oriented
and spun cast nonoriented films of the rigid rod conjugated polymer
poly(2,5-pyridinediyl) have been carried using different directions for
the polarization of the incident light and the direction of the applied
electric field. This has allowed us to separate the parallel and
perpendicular components (with respect to the polymer chain axis) of
the allowed optical transition 1A(g) --> 1B(u). The analysis of the
spectral dependence and anisotropy ratios of the absorption and
electroabsorption signals provides an indication of the existence of a
small number of delocalized Wannier-like excitons photogenerated by
light polarized perpendicular tcr the polymer chains. The majority of
excited states are, however, generated parallel to the chains forming
Frenckel excitons. In addition, we present results of electroabsorption
measurements on disordered (spin cast) poly(2,5-pyridinediyl) films in
a typical polymer light emitting diode configuration (sandwiched
between indium tin oxide and gold electrodes). We observe that the
electroabsorption signal is reduced by a factor of 100-1000 when
compared to the planar configuration, indicating a high intrinsic order
and alignment of the polymer chains parallel to the substrate in exact
agreement with elliposometric results on spun cast films. This property
is a consequence of the rigid rod nature of the poly(2,5-pyridinediyl)
chain.