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Ultrafast dynamics of singlet-singlet and singlet-triplet exciton annihilation in poly(3-2 '-methoxy-5 '-octylphenyl)thiophene films

Zaushitsyn, Yuri; Jespersen, Kim LU ; Valkunas, Leonas; Sundström, Villy LU and Yartsev, Arkady LU (2007) In Physical Review B (Condensed Matter and Materials Physics) 75(19).
Abstract
Singlet-singlet (S-S) and singlet-triplet (S-T) exciton annihilation was studied in poly(3-2(')-methoxy-5(')octylphenyl)thiophene films. For the S-S exciton annihilation studies, transient absorption spectroscopy at excitation laser pulse fluences of 1.2x10(13)-4.4x10(14) photons/cm(2) and 2.5 kHz pulse repetition rate was applied. The obtained kinetics demonstrate a typical nonexponential character with intensity-dependent amplitudes and lifetimes. In time-resolved fluorescence experiments, low excitation pulse fluences of 1.6x10(9)-2.2x10(12) photons/cm(2) at high repetition rates of 0.4, 0.8, 4, and 81 MHz lead to S-T exciton annihilation as a result of triplet exciton accumulation. S-T annihilation kinetics results in monoexponential... (More)
Singlet-singlet (S-S) and singlet-triplet (S-T) exciton annihilation was studied in poly(3-2(')-methoxy-5(')octylphenyl)thiophene films. For the S-S exciton annihilation studies, transient absorption spectroscopy at excitation laser pulse fluences of 1.2x10(13)-4.4x10(14) photons/cm(2) and 2.5 kHz pulse repetition rate was applied. The obtained kinetics demonstrate a typical nonexponential character with intensity-dependent amplitudes and lifetimes. In time-resolved fluorescence experiments, low excitation pulse fluences of 1.6x10(9)-2.2x10(12) photons/cm(2) at high repetition rates of 0.4, 0.8, 4, and 81 MHz lead to S-T exciton annihilation as a result of triplet exciton accumulation. S-T annihilation kinetics results in monoexponential decay of the fluorescence kinetics and manifests itself as a decrease of the singlet exciton lifetime. The calculated time-independent S-S and S-T exciton annihilation rates strongly support the conclusion that the processes are controlled by the interchain diffusion of singlet excitons. Despite the low efficiency of S-T annihilation compared to that of S-S annihilation, it has a substantial effect on the singlet exciton lifetime due to a relatively long triplet lifetime (60 mu s). Thus, even optical excitation with low fluence at high pulse repetition rate creates a significant concentration of triplet states that efficiently quenches singlet excitons. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review B (Condensed Matter and Materials Physics)
volume
75
issue
19
publisher
American Physical Society
external identifiers
  • wos:000246890800061
  • scopus:34247877548
ISSN
1098-0121
DOI
10.1103/PhysRevB.75.195201
language
English
LU publication?
yes
id
289aa936-1869-405e-b1ed-a2e219888c56 (old id 650614)
date added to LUP
2007-12-19 10:55:26
date last changed
2017-08-27 05:25:49
@article{289aa936-1869-405e-b1ed-a2e219888c56,
  abstract     = {Singlet-singlet (S-S) and singlet-triplet (S-T) exciton annihilation was studied in poly(3-2(')-methoxy-5(')octylphenyl)thiophene films. For the S-S exciton annihilation studies, transient absorption spectroscopy at excitation laser pulse fluences of 1.2x10(13)-4.4x10(14) photons/cm(2) and 2.5 kHz pulse repetition rate was applied. The obtained kinetics demonstrate a typical nonexponential character with intensity-dependent amplitudes and lifetimes. In time-resolved fluorescence experiments, low excitation pulse fluences of 1.6x10(9)-2.2x10(12) photons/cm(2) at high repetition rates of 0.4, 0.8, 4, and 81 MHz lead to S-T exciton annihilation as a result of triplet exciton accumulation. S-T annihilation kinetics results in monoexponential decay of the fluorescence kinetics and manifests itself as a decrease of the singlet exciton lifetime. The calculated time-independent S-S and S-T exciton annihilation rates strongly support the conclusion that the processes are controlled by the interchain diffusion of singlet excitons. Despite the low efficiency of S-T annihilation compared to that of S-S annihilation, it has a substantial effect on the singlet exciton lifetime due to a relatively long triplet lifetime (60 mu s). Thus, even optical excitation with low fluence at high pulse repetition rate creates a significant concentration of triplet states that efficiently quenches singlet excitons.},
  author       = {Zaushitsyn, Yuri and Jespersen, Kim and Valkunas, Leonas and Sundström, Villy and Yartsev, Arkady},
  issn         = {1098-0121},
  language     = {eng},
  number       = {19},
  publisher    = {American Physical Society},
  series       = {Physical Review B (Condensed Matter and Materials Physics)},
  title        = {Ultrafast dynamics of singlet-singlet and singlet-triplet exciton annihilation in poly(3-2 '-methoxy-5 '-octylphenyl)thiophene films},
  url          = {http://dx.doi.org/10.1103/PhysRevB.75.195201},
  volume       = {75},
  year         = {2007},
}