Something New and Blue for Display and Lighting Applications
US Patent No. 8,957,217 granted on February 17, 2015
OLED materials that use charge-neutral blue light are highly desirable because their shorter wavelength can be used to excite other phosphors to produce light of different colors. They are also particularly indispensable in producing white light. However, these blue emissions have, until now, only been achieved using iridium-based complexes and these iridium-based complexes are all held by a small number of companies with strong patent protection. Therefore, there is a need to break this monopoly and to discover new OLED materials using other metal centers such as platinum, palladium and gold.
One step in that direction is this newly-granted patent, which relates to a new class of bis-(NHC carbenes) alkylene ligand Pt(II) OLED materials that emit charge-neutral blue light. The chromaticity of a prototype OLED device fabricated using this material is CIExy(0.16, 0.16). Such color is well within the desirable blue spectral region. Moreover, a maximum brightness of 1,200cd/m2 and a peak luminous efficiency of 0.5cd/A produced by the prototype device were also recorded.