Abstract
Excitons in polycrystalline and disordered films of organic semiconductors have been shown to diffuse over distances of 10-50 nm. Here, using polarization- and wavelength-dependent photoconductivity in the highly ordered organic semiconductor rubrene, we show that the diffusion of triplet excitons in this material occurs over macroscopic distances (2-8 μm), comparable to the light absorption length. Dissociation of these excitons at the surface of the crystal is found to be the main source of photoconductivity in rubrene. In addition, we observe strong photoluminescence quenching and a simultaneous enhancement of photoconductivity when the crystal surface is functionalized with exciton splitters. In combination with time-resolved measurements, these observations strongly suggest that long-lived triplet excitons are indeed generated in molecular crystals by fission of singlets, and these triplets provide a significant contribution to the surface photocurrent generated in organic materials. Our findings indicate that the exciton diffusion bottleneck is not an intrinsic limitation of organic semiconductors.
| Original language | English |
|---|---|
| Pages (from-to) | 938-943 |
| Number of pages | 6 |
| Journal | Nature Materials |
| Volume | 9 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - Nov 2010 |
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ASJC Scopus subject areas
- Mechanical Engineering
- Mechanics of Materials
- Condensed Matter Physics
- Materials Science(all)
- Chemistry(all)
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Observation of long-range exciton diffusion in highly ordered organic semiconductors. / Najafov, H.; Lee, B.; Zhou, Q.; Feldman, Leonard C; Podzorov, V.
In: Nature Materials, Vol. 9, No. 11, 11.2010, p. 938-943.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Observation of long-range exciton diffusion in highly ordered organic semiconductors
AU - Najafov, H.
AU - Lee, B.
AU - Zhou, Q.
AU - Feldman, Leonard C
AU - Podzorov, V.
PY - 2010/11
Y1 - 2010/11
N2 - Excitons in polycrystalline and disordered films of organic semiconductors have been shown to diffuse over distances of 10-50 nm. Here, using polarization- and wavelength-dependent photoconductivity in the highly ordered organic semiconductor rubrene, we show that the diffusion of triplet excitons in this material occurs over macroscopic distances (2-8 μm), comparable to the light absorption length. Dissociation of these excitons at the surface of the crystal is found to be the main source of photoconductivity in rubrene. In addition, we observe strong photoluminescence quenching and a simultaneous enhancement of photoconductivity when the crystal surface is functionalized with exciton splitters. In combination with time-resolved measurements, these observations strongly suggest that long-lived triplet excitons are indeed generated in molecular crystals by fission of singlets, and these triplets provide a significant contribution to the surface photocurrent generated in organic materials. Our findings indicate that the exciton diffusion bottleneck is not an intrinsic limitation of organic semiconductors.
AB - Excitons in polycrystalline and disordered films of organic semiconductors have been shown to diffuse over distances of 10-50 nm. Here, using polarization- and wavelength-dependent photoconductivity in the highly ordered organic semiconductor rubrene, we show that the diffusion of triplet excitons in this material occurs over macroscopic distances (2-8 μm), comparable to the light absorption length. Dissociation of these excitons at the surface of the crystal is found to be the main source of photoconductivity in rubrene. In addition, we observe strong photoluminescence quenching and a simultaneous enhancement of photoconductivity when the crystal surface is functionalized with exciton splitters. In combination with time-resolved measurements, these observations strongly suggest that long-lived triplet excitons are indeed generated in molecular crystals by fission of singlets, and these triplets provide a significant contribution to the surface photocurrent generated in organic materials. Our findings indicate that the exciton diffusion bottleneck is not an intrinsic limitation of organic semiconductors.
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U2 - 10.1038/nmat2872
DO - 10.1038/nmat2872
M3 - Article
VL - 9
SP - 938
EP - 943
JO - Nature Materials
JF - Nature Materials
SN - 1476-1122
IS - 11
ER -