Hamburg 2001 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
SYOF: Organische Festkörper
SYOF 5: Poster Session
SYOF 5.19: Poster
Tuesday, March 27, 2001, 17:00–19:00, Aula S3
Doping Of Zinc-Phthalocyanine With Acceptor Molecules: An ESR Investigation — •M. Pfeiffer1, A. Nollau1, K. Leo1, D. Habermann2, and J.R. Niklas2 — 1Institut für Angewandte Photophysik, TU Dresden, 01062 Dresden — 2Institut für Experimentelle Physik, TU Bergakademie Freiberg, 09599 Freiberg
We have recently shown that doping of organic molecular films with molecular dopants strongly improves the properties of organic devices like LEDs and solar cells (M. Pfeiffer et al., Advances in Solid State Physics, 39, 77 (1999)). The process of doping is investigated by electron spin resonance (ESR) measurements on zinc-phthylocyanine (ZnPc) doped with tetrafluoro-tetracyano-quinodimethane (F4-TCNQ). ZnPc / F4-TCNQ is a good model system for the investigation of the doping process: The doping increases the conductivity by up to eight orders of magnitude, and it is known that all acceptor molecules are ionized.
The ESR spectra show a single peak for all doping levels. The intensity of the signal increases linearly with the dopant concentration up to about 2% and then decreases again. The linewidth of the ESR signal is narrowed upon doping for concentrations below 2 % due to motional narrowing.
From the experimental results we conclude that, firstly, the total density of charge carriers is proportional to the dopant density. Secondly, the effective mobility of the charge carriers is increased by doping.