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Phosphorescence and spin-dependent exciton formation in conjugated polymers

Title data

Köhler, Anna ; Wilson, Joanne S.:
Phosphorescence and spin-dependent exciton formation in conjugated polymers.
In: Organic Electronics. Vol. 4 (2003) Issue 2-3 . - pp. 179-189.
ISSN 1566-1199
DOI: https://doi.org/10.1016/j.orgel.2003.08.011

Abstract in another language

The mechanism for the formation of singlet and triplet states in conjugated polymer-based light-emitting diodes (LEDs) is crucial in determining the overall efficiencies of these devices. If simple spin statistics apply then singlets and triplets should be formed in the ratio 25:75. However, the non-emissive nature of triplet states in these materials, as well as other loss mechanisms within the devices, mean that this ratio is not straightforward to measure. Nevertheless, recent experimental advances have made it possible to determine many of the properties of triplet states. Here we review what is now known about triplet states and their photophysics in conjugated polymers. We place particular emphasis on measurements of the singlet generation fraction in LEDs, and discuss the experimental techniques that have been used, such as direct comparison of photoluminescence and electroluminescence efficiencies, triplet absorption cross section measurements and magnetic resonance measurements. All of these techniques give values for the singlet generation fraction in polymers that are significantly larger than the 25% expected, and many of them have also shown that in shorter oligomers this value decreases to be closer to 25%. We also give a brief overview of recent theories for the processes of singlet and triplet formation in polymer devices.

Further data

Item Type: Article in a journal
Refereed: No
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Lehrstuhl Experimentalphysik II - Optoelektronik weicher Materie > Lehrstuhl Experimentalphysik II - Optoelektronik weicher Materie - Univ.-Prof. Dr. Anna Köhler
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Lehrstuhl Experimentalphysik II - Optoelektronik weicher Materie
Result of work at the UBT: No
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 18 Mar 2015 08:11
Last Modified: 18 Mar 2015 08:11
URI: https://eref.uni-bayreuth.de/id/eprint/8458