Exciton annihilation in a polyfluorene: Low threshold for singlet-singlet annihilation and the absence of singlet-triplet annihilation

King, S.M.; Dai, D.; Rothe, C.; Monkman, A.P.

doi:10.1103/physrevb.76.085204

Exciton annihilation in a polyfluorene: Low threshold for singlet-singlet annihilation and the absence of singlet-triplet annihilation

King, S.M.; Dai, D.; Rothe, C.; Monkman, A.P.

Authors

S.M. King

D. Dai

C. Rothe

Professor Andrew Monkman a.p.monkman@durham.ac.uk
Professor

Abstract

Ultrafast photoinduced absorption measurements have been used to directly investigate singlet-singlet annihilation in polyfluorene. The pump fluence threshold for annihilation to dominate the decay was measured to be ∼1 μJ cm−2 corresponding to an excitation density of 1.5×1017 cm−3. The annihilation rate was found to be faster than that expected from a simple dipole-dipole interaction. This is ascribed to the additional influence of diffusion which, because of the dispersive nature of the exciton migration, has strong time dependence as the singlet excitons thermalize in the density of states as well as the expected intrinsic time dependence from a diffusion controlled process. Also, a comparable background level of triplets was created in the film to study the effect of singlet-triplet annihilation, which surprisingly, given the low threshold for singlet-singlet annihilation, was found to be negligible.

Citation

King, S., Dai, D., Rothe, C., & Monkman, A. (2007). Exciton annihilation in a polyfluorene: Low threshold for singlet-singlet annihilation and the absence of singlet-triplet annihilation. Physical review B, 76(8), https://doi.org/10.1103/physrevb.76.085204

Journal Article Type	Article
Publication Date	Aug 1, 2007
Deposit Date	Sep 29, 2010
Publicly Available Date	Oct 19, 2010
Journal	Physical Review B
Print ISSN	1098-0121
Electronic ISSN	1550-235X
Publisher	American Physical Society
Peer Reviewed	Peer Reviewed
Volume	76
Issue	8
DOI	https://doi.org/10.1103/physrevb.76.085204