Non-doped-type white organic light-emitting devices based on yellow-emitting ultrathin 5,6,11,12-tetraphenylnaphthacene and blue-emitting 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl

Non-doped-type white organic light-emitting devices based on the ultrathin yellow-emitting layer (0.1 nm) of 5,6,11,12-tetraphenylnaphthacene (rubrene) and the thick blue-emitting layer of 4,4′-bis(2,2′-diphenyl vinyl)-1,1′-biphenyl (DPVBi) made from vacuum-deposited organic thin films are reported. The recombination zone of the devices can be adjusted by changing the thicknesses of DPVBi and the electron transport layers (tris-(8-hydroxyquinoline)aluminium, Alq₃). In the device with 30 nm DPVBi and 30 nm Alq₃, bright white light, over 10 000 cd m^-2, was successfully obtained at a low drive voltage of ∼10 V. The highest power efficiency is 3.18 lm W^-1 at 4 V, and stable 1931 Commission International de L'Eclairage coordinates are obtained for luminance ranging from 100 to 20000 cd m^-2 (at ∼ 12 V).