Effects of triplet exciton confinement induced by reduced conjugation length in polyspirobifluorene copolymers.
Using gated optical spectroscopy at low temperatures, a polyspirobifluorene has been compared with an alternating carbazole-spirobifluorene copolymer in which the backbone conjugation is interrupted due to meta coupling of the carbazole moieties. In the copolymer both singlet and triplet energy levels are blueshifted by 130 meV with respect to the homopolymer, resulting in an unaltered singlet-to-triplet splitting. Though the barrier for triplet exciton migration increases from 4.4 to 6.0 meV for the copolymer compared to the homopolymer, it still remained low enough to ensure efficient triplet diffusion at ambient temperature.
Rothe
C
C
Department of Physics, University of Durham, Durham DH1 3LE, United Kingdom. carsten.rothe@dur.ac.uk
Brunner
K
K
Bach
I
I
Heun
S
S
Monkman
A P
AP