Efficient deep blue fluorescent OLEDs with ultra-low efficiency roll-off based on 4H-1,2,4-triazole cored D-A and D-A-D type emitters

Four novel 4H-1,2,4-triazole (TAZ)-cored D-A and D-A-D type deep blue emitters were obtained and the non doped OLEDs employing one of them as emitters exhibited fantastic performances with maximum EQE of 6.3% and CIE coordinates of (0.158, 0.038) as well as demonstrated ultra-low efficiency roll-off. The EL spectra of the OLEDs have very narrow FWHM (full width at half maximum) of 48 nm-50 nm, which means the excellent color purity. If using the CIED(x,y) of our OLEDs as the blue point, and the green and red CIE(x,y) of NTSC (National Television System Committee) as the green and red points, the color gamut will exceed 100%, which was thought to be the unique advantage of quantum-dots-based LEDs. To the best of our knowledge, these are the best results to date for deep blue OLEDs with CIE(y) coordinate < 0.04.