The progress of white light-emitting diodes (WOLEDs) holds capability for the production of high-performance surface light sources, but the commercialization is significantly delayed owing to the usage of expensive noble metal phosphorescent complexes. Recently, a series of thermally activated delayed fluorescent (TADF) Cu(I) complexes featuring carbene–Cu(I)–amine two-coordinate geometries exhibit promising electroluminescent (EL) properties in OLEDs. With 6-trifluoromethyl-indole, 3-cyano-carbazole, and 3,6-dimethoxy-carbazole, blue and yellow TADF Cu(I) complexes are prepared, exhibiting decent PL quantum yield and short decay lifetimes. Taking advantages of their broad emission spectra and high thermal stabilities, WOLEDs are designed based on blue and yellow TADF Cu(I) complexes. Pure white and warm white illuminations can be obtained by tuning the combination ratios of the emitters. A high external quantum efficiency over 13%, a decent color-rendering index (CRI) over 80, and stable white emission in a wide range of luminances demonstrate the potential of these low-cost emissive dopants in the field of WOLEDs.
Feng et al. (Fri,) studied this question.