Organic Light Emitting Diodes with Reduced Spectral and Spacial Halfwidths

Organic light emitting diodes (OLEDs) with reduced spectral and spacial halfwidths for full-color imaging applications are investigated. The electroluminescence behaviour of the lanthanide complexes Eu(TTFA)3Phen and Tb(ACAC)3Phen having sharp emission lines in the red and green spectrum, respectively, is examined for different OLED structures. Device optimization criteria with respect to multilayer design and material choice for this type of device are given. A Fabry-P?rot microcavity OLED is investigated to narrow the spectral width of commonly used organic materials (e.g. Alq3) from 100 nm to only 13 nm, demonstrating blue and green emission. In addition, the forward emission at the resonance wavelength is 8 times higher in intensity accompanied by a reduced spacial halfwidth. The directivity is further improved using materials with inherent narrow spectral widths. A spacial full-width at half maximum (FWHM) of 12? is demonstrated if the europium complex Eu(TTFA)3Phen is embedded into a microcavity structure. Compared to a non-cavity device as a reference, the emission intensity in this direction is significantly enhanced by a factor of about?8.