Efficient white organic light emitting diodes with solution processed and vacuum deposited emitting layers

The white light emitting diode based on small molecules, which have double emitting layers, was fabricated by combining a solution process and a vacuum deposition process. The organic light emitting diode that we have prepared utilizes a three phosphorescent guest materials, iridium(III)bis(4′,6′-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate, fac tris(2-phenylpyridine) iridium (III) and tris[1-phenylisoquinolinato-C2,N] iridium (III), exhibits a high color rendering index of over 82. Despite its ease of fabrication, the peak power efficiency was about 16 lm/W. The high efficiency was attributed to the distribution of the emitting region over the two emitting layers, which is caused by energy transfer between the phosphorescent guests.