Iridium(III) bis[2-(2-naphthyl)pyridine] (acetylacetonate)-based yellow and white phosphorescent organic light-emitting devices
We report the synthesis of a new biscyclometalated yellow phosphorescent dopant iridium(III) bis[2-(2-naphthyl)pyridine](acetylacetonate) (Ir(npy)2acac) and studies of its application in organic light-emitting devices (OLEDs), in which highly efficient yellow-emitting OLEDs with high peak forward viewing efficiencies of 34 cd A−1, 22 lm W−1, and 11% can be obtained, along with the Commission de L'Eclairage 1931 chromaticity coordinates of (0.45, 0.54). More importantly, yellow phosphorescence can be achieved without the formation of excimer emission. Particularly, such devices exhibit a very broad and featureless peak at ca. 550 nm with a wide full spectral width at half maximum (FWHM) of 87 nm. Furthermore, combination with iridium(III) bis[(3,4,5,-trifluorophenyl)-pyridinato-N,C2′]picolinate doped p-bis-(triphenylsilyly)benzene as the blue-emitting layer yields highly efficient white OLEDs with maximum efficiencies as high as 46 cd A−1 and 41 lm W−1 in the forward direction, making Ir(npy)2acac a promising organic phosphor for applications in yellow and white OLEDs.