Regensburg 2002 – wissenschaftliches Programm

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SYOH: Organische Halbleiter

SYOH 7: Poster

SYOH 7.35: Poster

Montag, 11. März 2002, 18:00–21:00, C

Polymeric PEDT:PSS Anode for Improved Hole Injection and Performance of Mutilayer OLED — •Fapei Zhang, Andreas Petr, Uwe Kirbach, and Lothar Dunsch — Group of Electrochemistry and Conducting Polymer, Institute for Solid State and Materials Research Dresden, D-01069 Dresden, Germany

We introduce stable conducting PEDT:PSS (poly(3,4-ethylenedioxythiophene)/poly(styrenesufonate)) film as hole-injection contact in small molecular OLED. The layer was prepared by spin- coating from aqueous PEDT:PSS solution. they are smooth as shown by SEM, and shows metallic feature. The operation of hole-only devices indicates that PEDT:PSS layer can remarkably improve the hole injection between ITO and naphthyl- substituted benzidine (NPB) layer. In NPB/Alq3 bilayer OLED using PEDT:PSS as injection contact, leakage current at lower fields, as well as electric short circuiting is eliminated due to the smoothing of ITO by the polymer layer. The devices show a reduction of operating voltage (about 2V), as well as enhanced efficiency, compared to the NPB/Alq3 structure without PEDT:PSS layer. It is demonstrated that the incorporation of a polymerization process into vapor-deposited small molecular OLED is an alternative approach to improve the performance of OLEDs. The electrochemical change of the doping level of PEDT and its influence on charge carrier injection in multilayer OLED is shown for first time. It will be encouraging for futher investigation of these anode structure to tune the doping level of conducting polymer/small molecular interface.