Dresden 2009 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
CPP: Fachverband Chemische Physik und Polymerphysik
CPP 22: Fokus: Conjugated Polymers
CPP 22.6: Topical Talk
Mittwoch, 25. März 2009, 12:00–12:30, ZEU 160
From amorphous polymers to discotic liquid crystals - Measuring charge carrier mobility with the time-of-flight technique — •Frederic Laquai1, Dirk Hertel2, Marcel Kastler1, Klaus Muellen1, and Gerhard Wegner1 — 1Max-Planck-Institut für Polymerforschung, Mainz, Germany — 2University of Cologne, Germany
The charge carrier mobility is one of the key parameters of conjugated materials that greatly determines the performance of electronic devices. It can be measured by various techniques, for instance, the time-of-flight (TOF) technique, space-charge limited current measurements or pulsed radiolysis time resolved microwave conductivity measurements. Here, the charge-generation-layer TOF technique has been used to study hole mobility of a series of amorphous poly-spirobifluorene copolymers. The copolymers contain different concentrations of triarylamine units in the polymer backbone and have mobilities in the range of 10−6 − 10−4 cm2/Vs. The results of the field and temperature dependent measurements can be well interpreted in the framework of the 3D-Gaussian disorder formalism. The experiments show that high hole mobility does not necessarily lead to high performance in OLEDs. Secondly, the TOF technique has been employed to study hole transport in hexa-peri-hexabenzocoronene molecules that can be organised into face-on or edge-on arrangements between substrates depending on the nature of the alkyl-chains attached to the molecule. Mobilities of 10−3 cm2/Vs have been determined and results could be well analysed in the framework of a 1D-transport model.