Berlin 2005 – wissenschaftliches Programm
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SYOO: Organic Optoelectronics and Photonics
SYOO 6: Poster
SYOO 6.28: Poster
Montag, 7. März 2005, 18:00–20:00, Poster TU A
Acridine orange base as a dopant for n-doping of C60 thin films — •Fenghong Li1, Ansgar Werner1, Martin Pfeiffer1, Karl Leo1, and Naoki Hayashi2 — 1Institut für Angewandte Photophysik , Technische Universität Dresden, D-01062 Dresden, Germany — 2Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
we present a study on n-doping of C60 thin films by acridine orange base (AOB) combining conductivity, field effect and Seebeck measurements. It is found that the dark conductivity of C60 doped thin films can be enhanced by a light-induced activation of dopant precursor AOB: A conductivity up to 6*10-2 S/cm at 30oC is achieved when a diffusive illumination is provided in the vacuum chamber during the evaporation. The field effect and Seebeck measurements comfirm the n-type conduction of C60 thin films and show that deep donor states are formed in AOB doped C60 films. A field effect mobility of 0.19 cm2/Vs is achieved for a doping level of 56:1. NIR and FTIR spectra demonstrate electron transfer from the dopant to the matrix: For C60 doped with AOB, C60 anion is present in NIR absorption and FTIR spectra. On the other hand, a peak corresponding to acridine orange (AO cation) is also observed in the FTIR spectrum of C60:AOB, where AO corresponds to AOB with one additional hydrogene attached. Electrochemical data of AOB and AO in acetontrile suggest that the AOB radical cation is not stable but is rapidly transformed into a compound with similar properties to AO. We speculate that, in the codeposited layers, this compound is a dyad of AOB(+) and C60(-) connected by a C-N chemical bond.