Hostname: page-component-76fb5796d-zzh7m Total loading time: 0 Render date: 2024-04-26T04:55:05.249Z Has data issue: false hasContentIssue false
  • English
  • Français

Optical Probing of Polarons and Triplet Excitons in Conjugated Polymer Devices

Published online by Cambridge University Press:  21 March 2011

Anoop S. Dhoot  and
Neil C. Greenham
Anoop S. Dhoot
Affiliation:
Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, United Kingdom
Neil C. Greenham
Affiliation:
Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, United Kingdom
Get access

Abstract

Polarons and triplet excitons in conjugated polymers exhibit sub-gap absorptions which allow them to be identified spectroscopically. We have used quasi-steady-state induced absorption techniques on working polymer light-emitting diodes to study charge carriers and triplet excitons in devices. We identify absorptions due to charges, and at low temperatures can also resolve features due to triplet excitons. From the magnitude of the absorption features, we study the charge and triplet densities as a function of applied voltage. We obtain a value for the triplet generation rate at low temperatures and an estimate of the singlet exciton formation probability. Analysis of the triplet lifetime as a function of charge density reveals the presence of triplet-polaron interactions and we obtain a rate constant for this triplet annihilation process.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 665: Symposium C – Electronic, Optical and Optoelectronic Polymers and Oligomers , 2001 , C1.6
Copyright
Copyright © Materials Research Society 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Friend, R. H., Gymer, R. W., Holmes, A. B., Burroughes, J. H., Marks, R. N., Taliani, C., Bradley, D. D. C., Santos, D. A. D., Brédas, J. L., Logdlund, M., and Salaneck, W. R., Nature 397, 121 (1999).Google Scholar
2. Cao, Y., Parker, I. D., Yu, G., Zhang, C., and Heeger, A. J., Nature 397, 414 (1999).Google Scholar
3. Kim, J. S., Ho, P. K. H., Greenham, N. C., and Friend, R. H., J. Appl. Phys. 88, 1073 (2000).Google Scholar
4. Wohlgenannt, M., Tandon, K., Mazumdar, S., Ramasesha, S., and Vardeny, Z. V., Nature 409, 494 (2001).Google Scholar
5. Brown, A. R., Pichler, K., Greenham, N. C., Bradley, D. D. C., Friend, R. H., and Holmes, A. B., Chem. Phys. Lett. 210, 61 (1993).Google Scholar
6. Redecker, M. and Bässler, H., Appl. Phys. Lett. 69, 70 (1996).Google Scholar
7. Kozlov, V. G., Burrows, P. E., Parthasarathy, G., and Forrest, S. R., Appl. Phys. Lett. 74, 1057 (1999).Google Scholar
8. Tessler, N., Harrison, N. T., and Friend, R. H., Adv. Mater. 10, 64 (1997).Google Scholar
9. Campbell, I. H., Smith, D. L., Neef, C. J., and Ferraris, J. P.,Appl. Phys. Lett. 78, 270 (2001).Google Scholar
10. Hamberg, I. and Granqvist, C. G., J. Appl. Phys. 60, R123 (1986).Google Scholar
11. Eldering, C. A., Knoesen, A., and Kowel, S. T., J. Appl. Phys. 69, 3676 (1991).Google Scholar
12. Wei, X., Vardeny, Z. V., Sariciftci, N. S., and Heeger, A. J., Phys. Rev. B 53, 2187 (1996).Google Scholar
13. Ginger, D. S. and Greenham, N. C., Phys. Rev. B 59, 10622 (1999).Google Scholar
14. Candeias, L. P., Wildeman, J., Hadziioannou, G., and Warman, J. M., J. Phys. Chem. B 104, 8366 (2000).Google Scholar
15. Pope, M. and Swenberg, C. E., “Electronic Processes in Organic Crystals and Polymers”, (Oxford University Press, Oxford, 1999).Google Scholar