Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 6: Electronic+Optical Properties
CPP 6.2: Vortrag
Montag, 25. Februar 2008, 14:15–14:30, C 230
Solution processable Cs-salt cathode structures for Polymer-LEDs — •Riikka Suhonen1,2, Andreas Kanitz1, Wiebke Sarfert1, Ralph Pätzold3, and Albrecht Winnacker2 — 1Siemens AG, CT MM1, Günther-Scharowsky-Str. 1, 91058 Erlangen, Germany — 2Department of Material Science VI, University Erlangen-Nuremberg, Martensstraße 7, 91058 Erlangen, Germany — 3OSRAM Opto Semiconductors GmbH, Leibnizstraße 4, 93055 Regensburg, Germany
The thin layers between the cathode and the polymer in polymer light emitting diodes (PLEDs) have been shown to have a big impact on the final device performance. Usually, in PLEDs low work function metals like Ba, Mg or Ca are used to reduce the energy barrier height between the cathode and the polymer thus providing a better electron injection from the cathode. Due to the high reactivity and quenching properties of these metals, search for electron injecting materials to replace them is ongoing. Recently, several alkali salts like LiF, CsF and Cs2CO3 have been shown to efficiently work as an electron injection layer. From these materials especially Cs2CO3 has proven to work very efficiently both as an electron injection layer.
In this contribution, we compare the performance of two cesium salts, cesium carbonate (Cs2CO3) and cesium stearate (CsSt). Both of these salts can be deposited from solution and by vacuum evaporation. Additionally, both of the salts show comparable or even better performance in comparison to the standard Ba cathode. Also the long term stability of the salt-cathode structures has been investigated.