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Journal of Materials Science and Nanotechnology | Volume: 2
August 20-21, 2018 | Paris, France
Materials Science and Materials Chemistry
International Conference on
Temperature dependent interplay between emitting species in highly ordered poly(thiophenes) as
revealed by optical spectroscopy
Agumba OJ
Pwani University, Kenya
I
n this study, the temperature dependent PL spectra
measurement has provided us a feasible means to elucidate
the nature of the emissive species and the melt transitions in
different polythiophenes. The effects of thermal fluctuation
on different phases of a bulky substituted poly (3-(2,
5-dioctylphenyl) thiophene) (PDOPT) and Poly(3 hexylthiopne-2
5diyl) (P3HT) have been systematically investigated using
photoluminescence spectroscopy. This has been achieved by
performing in-situ temperature dependent photoluminescence
measurements followed by detailed spectral analysis. For
PDOPT, the intensities of the emitted species varied as a
function of temperature that determine degrees of order.
Well-ordered crystals emitted strongly in lower energies as
opposed to less ordered films and spherulitic crystals. From
the deconvoluted PL spectra, it was revealed that, the emitting
energy bands remained constant with shift of intensity with
ordered crystals emitting strongly in higher wavelengths as
compared to their disordered counterparts that emit strongly in
lower wavelengths. On the other hand, for P3HT, the spectrally
resolved PL lineshapes through multipeak Gaussian functions
simulating 0-0, 0-1, 0-n peaks have revealedmultiple vibrational
replicas yielding different emitting species (states). We suggest
that the temperature dependent vibronic progressions
arise from different electronic origins i.e. different species
(fluorophores) due to multiple crystalline polymorphs within
the crystal with varied coupling of the excited states. From our
observation, we conclude that it is not sufficient to invoke only
the intramolecular interactions in explaining the nature of PL
spectra of highly ordered polythiophenes which are widely
dominated by both interchain and intrachain interactions.
e:
agumba.john@gmail.com