High efficiency white organic light-emitting devices by effectively controlling exciton recombination region

Abstract

An efficient white organic light-emitting device was fabricated. The used device was a multilayer structure of ITO/N,N-bis-(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) (30 nm)/NPB: DCJTB: C545T (10 nm)/NPB (4 nm)/DNA (8 nm)/2,9-dimethyl, 4,7-diphenyl, 1,10-phenanthroline (BCP) (9 nm)/tris-(8-hydroxyquinoline) aluminium (Alq3) (30 nm)/LiF (1 nm)/Al (100 nm). In our devices, a red dye 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyl julolidyl-9-enyl)-4H-pyran and a green dye 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-(1)-benzopyropyrano(6,7–8-i,j)quinolizin-11-one were co-doped into NPB and sandwiched between two pure NPB layers. The introduction of the co-doping layer as well as the multilayer structure permits us to control the exciton recombination region well, thereby producing stable white light emission in a wide range of voltage. The device shows a turn-on voltage of 5.9 V and a maximum luminance of 13 600 cd m−2. The power efficiency and current efficiency reach 4.4 lm W−1 and 12.3 cd A−1, respectively.