Synthesis and Characterization of 9-(Fluoren-2-yl)anthracene Derivatives as Efficient Non-Doped Blue Emitters for Organic Light-Emitting Diodes

A series of 9-(fluoren-2-yl)anthracene derivatives bearing either thiophene (FATh), triphenylamine (FAT and FATT) or pyrene (FATP) moieties as substituents have been designed, synthesized, and characterized as non-doped blue emitters for organic light-emitting diodes (OLEDs). Their optical, electrochemical and thermal properties have been investigated, and their molecular structure-property relationships were evaluated. All FAT, FATT and FATP compounds possess combined blue-light-emitting and hole-transporting characteristics, and showed stable amorphous states with high fluorescence quantum yields in solution (up to 89%) and strong luminance in the OLED devices, whereas FATh showed poor photoluminescent and electroluminescent properties. Efficient, non-doped blue and Alq3-based green OLEDs were fabricated and characterized. The blue and green devices with maximum luminance efficiencies and CIE coordinates of 3.17 cdA-1 and (0.13, 0.14), and 3.81 cdA-1 and (0.28, 0.50) were achieved, respectively, with FATT having 4-{bis[4-(diphenylamino)biphenyl-4-yl]amino}phenyl substituents as emitting layer and hole-transporting layer, respectively. These devices also showed considerably low turn-on voltages of 3.0 and 2.6 V, respectively.