Abstract
New functionalized- and bis-benzo[b]furan derivatives were synthesized and developed as blue-light emitting materials. These benzo[b]furans possessed a CHO, CN, CH=CHCOOH, CH=CHPh, or CH=CPh2 group at the C4-position and have been synthesized by use of Sonogashira and Horner–Wadsworth–Emmons reaction; the two benzo[b]furan nuclei in bisbenzo[b]furan derivatives were connected by a divinylbenzene bridge. The Pd(0)/Cu(I) catalyzed coupling of (3,4-dimethoxyphenyl)acetylene with 4-substituted 2-hydroxy-3-iodoanisole followed by cyclization in situ was involved in the key step of their syntheses. Some of the benzo[b]furan derivatives show high quantum yield and fluorescence emission maximum between 450–482 nm. The bisbenzo[b]furan possess glass transition temperature Tg= 85 ºC. The device structure was ITO/NPB (40 nm)/19b (4.0%) in ADN (30 nm)/TPBI (10 nm)/Alq3 (30 nm)/Mg–Ag (50 nm)/Ag (10 nm), where ITO, NPB, 19b, ADN, TPBI, Alq3 were indium tin oxide, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl, (E,E)-1,4-bis([2-phenyl-7-methoxybenzo[b]furanyl]-4-vinyl)benzene, 9,10-di-(2-naphthyl)anthracene, 2,2',2"-(benzene-1,3,5-triyl)tris[1-phenyl-1H-benzimidazole], and tris(8-hydroxyquinoline)aluminum, respectively. The device had turn-on voltages (3.6 V) and was 303 cd/m2 at 6.0 V and 1298 cd/m2 at 7.0 V with Commission Internationale de L'Eclairage chromaticity coordinates of x = 0.15; y = 0.25 at 7.0 V. The maximum brightness reached 53430 cd/m2 at 15.5 V. The maximum external quantum efficiency was 3.75% (2.03 lm/w).