Electroluminescence metal-organic interface

The basic structure of a typical OLED is shown in Fig. 3.1 [35]. It consists of a transparent conducting anode, typically indium tin oxide (ITO) coated on a glass or plastic mechanical support, the organic layers, and a metal cathode. The thickness of OLEDs (excluding the mechanical support) is typically <0.5 j,m. Under forward bias electrons are injected from the low-workfunction cathode into the electron-transport layer (ETL). Similarly, holes are injected from the high-workfunction ITO into the hole-transport layer (HTL). Due to the applied bias, the electrons and holes drift toward each other, and typically recombine in a recombination zone near, or at, the ETL/HTL interface. A fraction of the recombination events forms radiative excited states. The radiative decay of these states provides the electroluminescence (EL) of the device. 

Endo, J., Matsumoto, T., and Kido, J. 2002. Organic electroluminescent devices having metal complexes as cathode interface layer. ]pi.. Appl. Phys. 41 L800. 

J. L. Bredas and W. R. Salaneck, Characterization of the interfaces between low workfunction metals and conjugated polymers in light-emitting diodes, in Organic Electroluminescence (D. D. C. Bradley and T. Tsutsui, eds.), Cambridge Univ. Press, Cambridge, UK, in press. 

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