Alternating current electroluminescence (AC-EL) with organic light emitting material
We demonstrate a new approach for fabricating alternating current driven organic electroluminescent devices using the concept of doping in organic semiconductors. Doped charge transport layers are used for generation of charge carriers within the device, hence eliminating the need for injecting char...
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| Format: | Doctoral Thesis |
| Language: | English |
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Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden
2012
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| Online Access: | http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-89750 http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-89750 http://www.qucosa.de/fileadmin/data/qucosa/documents/8975/Thesis_Final.pdf |
| Summary: | We demonstrate a new approach for fabricating alternating current driven organic electroluminescent devices using the concept of doping in organic semiconductors. Doped charge transport layers are used for generation of charge carriers within the device, hence eliminating the need for injecting charge carriers from external electrodes.
The device is an organic-inorganic hybrid: We exploit the mechanical strength and chemical stability of inorganic semiconductors and combine it with better optical properties of organic materials whose emission color can be chemically tuned so that it covers the entire visible spectrum. The device consists of an organic electroluminescence (EL) layer composed of unipolar/ambipolar charge transport materials doped with organic dyes (10 wt% ) as well as molecularly doped charge generation layers enclosed between a pair of transparent insulating metal oxide layers. A transparent indium doped tin oxide (ITO) layer acts as bottom electrode for light outcoupling and Aluminium (Al) as top reflective electrode. The electrodes are for applying field across the device and to charge the device, instead of injection of charge carriers in case of direct current (DC) devices. Bright luminance of up to 5000 cd m-2 is observed when the device is driven with an alternating current (AC) bias. The luminance observed is attributed to charge carrier generation and recombination, leading to formation of excitons within the device, without injection of charge carriers through external electrodes.
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