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Department of Physics

Staff profile

Publication details for Professor Andy Monkman

Fonseca, SM, Pina, J, Arnaut, LG, de Melo, JS, Burrows, HD, Chattopadhyay, N, Alcacer, L, Charas, A, Morgado, J, Monkman, AP, Asawapirom, U, Scherf, U, Edge, R & Navaratnam, S (2006). Triplet-state and singlet oxygen formation in fluorene-based alternating copolymers. Journal Of Physical Chemistry B 110(16): 8278-8283.
  • Publication type: Journal papers: academic
  • ISSN/ISBN: 1520-6106
  • Keywords: STRUCTURE-PROPERTY RELATIONSHIPS; LIQUID-CRYSTALLINE POLYFLUORENE; ELECTRON-ELECTRON CORRELATION; LIGHT-EMITTING POLYMERS; PI-CONJUGATED POLYMERS; PULSE-RADIOLYSIS; LUMINESCENCE PROPERTIES; ELECTROLUMINESCENT DIODES; ALPHA-OLIGOTHIOPHENES; OPTICAL-PROPERT

Author(s) from Durham

Abstract

Data are reported on the triplet states of a series of fluorene-based
A-alt-B type alternating copolymers based on pulse radiolysis-energy
transfer and flash photolysis experiments. From the pulse radiolysis
experiments, spectra are given for eight copolymers involving
phenylene, thiophene, benzothiadiazole, and oligothien-ylenevinylene
groups. Quantum yields for triplet-state formation ((Phi(T)) have been
obtained by flash photolysis following laser excitation and in one case
by photoacoustic calorimetry. In addition, yields of sensitized
formation of singlet oxygen have been determined by time-resolved
phosphorescence and are, in general, in excellent agreement with the
Phi(T) values. In all cases, the presence of thiophene units is seen to
increase intersystem-crossing quantum yields, probably because of the
presence of the heavy sulfur atom. However, with the poly
[2,7-(9,9-bis(2'-ethylhexyl)fluorene)-alt-1,4-phenylene] (PFP),
thiophene S,S-dioxide (PFFSO2) and benzothiadiazole (F8BT) copolymers,
low yields of triplet formation are observed. With three of the
copolymers, the energies of the triplet states have been determined.
With PFP, the triplet energy is virtually identical to that of
poly[2,7-(9,9-bis(2'-ethylhexyl)fluorene)]. In contrast, with
fluorene-thiophene copolymers PFaT and PF3T, the triplet energies are
closer to those of thiophene oligomers, indicating that there is
significant conjugation between fluorene and thiophene units but also
that there is a more localized triplet state than with the homopolymers.