White Organic Light‐Emitting Diodes with Evenly Separated Red, Green, and Blue Colors for Efficiency/Color‐Rendition Trade‐Off Optimization

A novel yellowish‐green triplet emitter, bis(5‐(trifluoromethyl)‐2‐ p ‐tolylpyridine) (acetylacetonate)iridium(III) (1), was conveniently synthesized and used in the fabrication of both monochromatic and white organic light‐emitting diodes (WOLEDs). At the optimal doping concentration, monochromatic devices based on 1 exhibit a high efficiency of 63 cd A −1 (16.3% and 36.6 lm W −1 ) at a luminance of 100 cd m −2 . By combining 1 with a phosphorescent sky‐blue emitter, bis(3,5‐difluoro‐2‐(2‐pyridyl)phenyl)‐(2‐carboxypyridyl)iridium(III) (FIrPic), and a red emitter, bis(2‐benzo[ b ]thiophen‐2‐yl‐pyridine)(acetylacetonate)iridium(III) (Ir(btp) 2 (acac)), the resulting electrophosphorescent WOLEDs show three evenly separated main peaks and give a high efficiency of 34.2 cd A −1 (13.2% and 18.5 lm W −1 ) at a luminance of 100 cd m −2 . When 1 is mixed with a deep‐blue fluorescent emitter, 4,4′‐bis(9‐ethyl‐3‐carbazovinylene)‐1,1′‐biphenyl (BCzVBi), and Ir(btp) 2 (acac), the resulting hybrid WOLEDs demonstrate a high color‐rendering index of 91.2 and CIE coordinates of (0.32, 0.34). The efficient and highly color‐pure WOLEDs based on 1 with evenly separated red, green, blue peaks and a high color‐rendering index outperform those of the state‐of‐the‐art emitter, fac ‐tris(2‐phenylpyridine)iridium(III) (Ir(ppy) 3 ), and are ideal candidates for display and lighting applications.