Blue organic light-emitting diodes based on terpyridine-substituted triphenylamine chromophores

Two terprydine-substituted triphenylamine chromophores with rigid benzyl unit and flexible styryl unit, namely 4-[4-(2,2′:6′,2″-terpyridinyl)]phenyltriphenylamine (chromophore I) and 4-[4-(2,2′:6′,2″-terpyridinyl)] styryltriphenylamine (chromophore II), have been designed and applied as emitters in organic light-emitting diodes (OLED). Chromophores I and II show distinctly luminescent characteristics due to the role of different rigid phenyl/flexible styrl unit interlinking terprydine and triphenylamine units which have different lowest unoccupied molecular orbital (LUMO) levels. The fluorescence lifetime of chromophore I is 3-fold longer than that of chromophore II and the maximum brightness of device used chromophore I as a single-emitting-layer in OLED is 28-fold larger than that of chromophore II in OLED. Chromophore I as an emitter in OLED exhibit blue electroluminescence peak at 460 nm (Commission Internationale de L'Eclairage (CIE) x = 0.19, y = 0.22).153