Electroluminescence Based on Lanthanide Complexes

College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, PR. China. Email bianzq pku.edu.cn and chhuang pku.edu.cn 

Although the studies on OLEDs have achieved considerable success, it is still difficult to obtain pure emission colors from small organic molecules or conjugated polymers, because their emission spectra typically have a half peak width of about 100 nm. Lanthanide ions can exhibit spectrally narrow emission due to intra-atomic transitions within the 4f shell. Consequently, luminescent lanthanide complexes are good candidates as emitting materials in OLEDs. 

Rare Earth Coordination Chemistry Fundamentals and Applications Edited by Chunhui Huang 2010 John Wiley Sons (Asia) Pte Ltd. ISBN 978-0-470-82485-6 

Electroluminescence (EL) is the phenomenon by which electrical energy is converted into luminous energy by the recombination of electrons and holes in the emissive material [8], The basic structure of an OLED consists of a thin film of organic material sandwiched between two electrodes, an anode of high-work-function material such as indium tin oxide (ITO) on a glass substrate, and a cathode of a low-work-function metal such as calcium (Ca), magnesium (Mg), or aluminum (Al) or an alloy such as Mg Ag. 

Organic layers are deposited mainly by thermal evaporation or spin coating from solutions for small molecule or polymeric materials, respectively. Metal layers are usually made by thermal evaporation. All layers should be chemically stable, especially under the device operating conditions, and resistant to oxidation or photo-oxidation. 

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