Publication Type |
Journal Article |
School or College |
College of Science |
Department |
Physics |
Creator |
Vardeny, Zeev Valentine |
Other Author |
Wohlgenannt, M.; Graupner, W.; Leising, G. |
Title |
Photogeneration and recombination processes of neutral and charged excitations in films of a ladder-type poly(para-phenylene) |
Date |
1999-08 |
Description |
We introduce a version of the cw photomodulation technique, measured far from the steady state, for obtaining the quantum efficiency, η, of long-lived photoexcitations in p-conjugated polymers. We apply this technique to films of a ladder-type poly(para-phenylene) [mLPPP] for studying the photogeneration action spectra, η(E), and recombination kinetics of photogenerated neutral and charged excitations such as singlet and triplet excitons and charged polarons. Whereas the η(E) spectrum for singlet excitons shows a step function increase at a photon energy, E, close to the optical gap (=2.6 eV), both triplet and polaron η(E) spectra show, in addition, a monotonous rise at higher E. The rise for triplets is explained by singlet exciton fission into triplet pairs, and from a model fit we get the triplet exciton energy (.1.6 eV). For polarons this rise is modeled by an electron intersegment tunneling process. The electroabsorption spectrum is also measured and analyzed in terms of Stark shift of the lowest lying exciton, 1Bu, and enhanced oscillator strength of the important mAg exciton. A consistent picture for the lowest excited state energy levels and optical transitions in the neutral (singlet and triplet) and charged manifolds is presented. From both the exciton binding energy of =1.6 eV and the singlet-triplet energy splitting of =0.6 eV, we conclude that the e-e interaction in mLPPP is relatively strong. Our results are in good agreement with recent ab initio band structure calculations for several rr-conjugated polymers. |
Type |
Text |
Publisher |
American Physical Society |
Journal Title |
Physical Review B |
Volume |
60 |
Issue |
8 |
First Page |
5321 |
Last Page |
5330 |
DOI |
10.1103/PhysRevB.60.5321 |
citatation_issn |
0163-1829 |
Subject |
Photogeneration; Recombination process; Neutral excitations; Charged excitations; Ladder-type poly(para-phenylene) |
Subject LCSH |
Organic semiconductors; Organic semiconductors -- Optical properties; Thin films -- Optical properties; Exciton theory |
Language |
eng |
Bibliographic Citation |
Wohlgenannt, M., Graupner, W., Leising, G., & Vardeny, Z. V. (1999). Photogeneration and recombination processes of neutral and charged excitations in films of a ladder-type poly(para-phenylene) . Physical Review B, 60(8), 5321-30. |
Rights Management |
(c) American Physical Society http://dx.doi.org/10.1103/PhysRevB.60.5321 |
Format Medium |
application/pdf |
Format Extent |
144,186 bytes |
Identifier |
ir-main,9926 |
ARK |
ark:/87278/s6sn0tc2 |
Setname |
ir_uspace |
ID |
705268 |
Reference URL |
https://collections.lib.utah.edu/ark:/87278/s6sn0tc2 |