Indenofluorene‐Based Blue Fluorescent Compounds and Their Application in Highly Efficient Organic Light‐Emitting Diodes

Blue fluorescent compounds based on indenofluorene derivatives incorporating the (diphenylamino)arylvinyl group and di‐ tert ‐butylphenyl blocking units have been synthesized by Suzuki coupling and the Horner–Wadsworth–Emmons reaction. Their electroluminescence in multilayered OLEDs was examined; the devices have the structures ITO/DNTPD/NPB/MADN:blue dopant/Alq3/LiF/Al. A device with 7 % 2‐(3,5‐di‐ tert ‐butylphenyl)‐8‐(9,9‐diethyl‐2‐(diphenylamino)fluoren‐7‐ylethenyl)‐6,6,12,12‐tetraethylindeno[1,2‐ b ]fluorene ( 3 ) as blue dopant showed a luminous efficiency of 12.2 cd A –1 , a power efficiency of 6.08 lm W –1 , and an external quantum efficiency of 7.84 % at 20 mA cm –1 with CIE (Commission Internationale d'Énclairage) ( x , y ) coordinates of (0.148, 0.241) at 8.5 V. A deep‐blue OLED with CIE ( x , y ) coordinates of (0.153, 0.128) doped with 2‐(3,5‐di‐ tert ‐butylphenyl)‐8‐[9‐(3,5‐di‐ tert ‐butylphenyl)carbazol‐3‐ylethenyl]‐6,6,12,12‐tetraethylindeno[1,2‐ b ]fluorene ( 4 ) exhibited a luminous efficiency of 3.25 cd A –1 , a power efficiency of 1.74 lm W –1 , and an external quantum efficiency of 2.93 % at 20 mA cm –1 .