Highly-efficient blue electroluminescence based on two emitter isomers

Highly-efficient blue organic light-emitting devices with a nondoped device structure have been fabricated with two anthracene derivatives, 2,3,6,7-tetramethyl-9,10-(1-dinaphthyl)-anthracene (alpha-TMADN) and 2,3,6,7-tetramethyl-9,10-(2-dinaphthyl)-anthracene (beta-TMADN). The homemade alpha-TMADN, beta-TMADN, or their blend were used as the light-emitting materials, and 4,7-diphenyl-1,10-phenanthroline was used as the hole blocking and electron transporting material, N,N-'-biphenyl-N,N-'-bis-(1-naphenyl)-[1,1(')-biphenyl]-4,4(')-diamine was used as the hole transporting material. The brightness of the device with beta-TMADN as the light-emitting material is up to 10 000 cd/m(2) at 12 V with the maximum efficiency of 4.5 cd/A, which is better than that of the device with alpha-TMADN as the light-emitting material. The brightness of the same structure device with the blend of alpha-TMADN and beta-TMADN as the light-emitting material, in which the ratio of alpha-TMADN to beta-TMADN is 9:1, is more than 12 000 cd/m(2) at 15 V with the maximum efficiency of 5.2 cd/A. (C) 2004 American Institute of Physics.