Bright hybrid white light-emitting quantum dot device with direct charge injection into quantum dot

A bright white quantum dot light-emitting device (white-QLED) with 4-4-(1-phenyl-1H-benzodimidazol-2-yl)phenyl-2-3-(tri-phenylen-2-yl)phen-3-ylquinazoline deposited on a thin film of mixed green/red-QDs as a bilayer emitter is fabricated. The optimized white-QLED exhibits a turn-on voltage of 3.2 V and a maximum brightness of 3660 cd/m²@8 V with the Commission Internationale de l'Eclairage (CIE) chromaticity in the region of white light. The ultra-thin layer of QDs is proved to be critical for the white light generation in the devices. Excitation mechanism in the white-QLEDs is investigated by the detailed analyses of electroluminescence (EL) spectral and the fluorescence lifetime of QDs. The results show that charge injection is a dominant mechanism of excitation in the white-QLED.