Observation of long-range exciton diffusion in highly ordered organic semiconductors

H. Najafov, B. Lee, Q. Zhou, Leonard C Feldman, V. Podzorov

Research output: Contribution to journalArticle

301 Citations (Scopus)

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 languageEnglish
Pages (from-to)938-943
Number of pages6
JournalNature Materials
Volume9
Issue number11
DOIs
Publication statusPublished - Nov 2010

Fingerprint

Semiconducting organic compounds
organic semiconductors
Excitons
excitons
Photoconductivity
photoconductivity
Molecular crystals
Crystals
organic materials
electromagnetic absorption
Time measurement
Photocurrents
crystal surfaces
Light absorption
crystals
fission
photocurrents
LDS 751
Quenching
Photoluminescence

ASJC Scopus subject areas

  • Mechanical Engineering
  • Mechanics of Materials
  • Condensed Matter Physics
  • Materials Science(all)
  • Chemistry(all)

Cite this

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 journalArticle

Najafov, H. ; Lee, B. ; Zhou, Q. ; Feldman, Leonard C ; Podzorov, V. / Observation of long-range exciton diffusion in highly ordered organic semiconductors. In: Nature Materials. 2010 ; Vol. 9, No. 11. pp. 938-943.
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