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 CIE_(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.