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Title: Operational electrochemical stability of thiophene-thiazole copolymers probed by resonant Raman spectroscopy

We report on the electrochemical stability of hole polarons in three conjugated polymers probed by resonant Raman spectroscopy. The materials considered are all isostructural to poly(3-hexyl)thiophene, where thiazole units have been included to systematically deepen the energy level of the highest occupied molecular orbital (HOMO). We demonstrate that increasing the thiazole content planarizes the main conjugated backbone of the polymer and improves the electrochemical stability in the ground state. However, these more planar thiazole containing polymers are increasingly susceptible to electrochemical degradation in the polaronic excited state. We identify the degradation mechanism, which targets the C=N bond in the thiazole units and results in disruption of the main polymer backbone conjugation. The introduction of thiazole units to deepen the HOMO energy level and increase the conjugated backbone planarity can be beneficial for the performance of certain optoelectronic devices, but the reduced electrochemical stability of the hole polaron may compromise their operational stability.
Authors:
; ;  [1] ; ; ; ;  [2] ;  [2] ;  [3]
  1. Department of Physics and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ (United Kingdom)
  2. Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AY (United Kingdom)
  3. (United Kingdom)
Publication Date:
OSTI Identifier:
22490857
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 24; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; COPOLYMERS; ELECTROCHEMISTRY; EXCITED STATES; GROUND STATES; MOLECULAR ORBITAL METHOD; OPTOELECTRONIC DEVICES; POLARONS; POLYCYCLIC SULFUR HETEROCYCLES; RAMAN SPECTROSCOPY; STABILITY; THIOPHENE