Improved white organic electroluminescent devices using fine mesh as an evaporation mask

We describe an improvement of a white organic EL devices using fine mesh as an evaporation mask. The bright white emission was obtained by controlling the ratio of emission area 4,4′-bis(2,2-diphenylvinyl)-1,1′-biphenyl (DPVBi) as a blue emitting layer and 5,6,11,12-tetraphenylnaphthacene (rubrene) as a yellow emitting layer. The device with 2,5-bis(6′-(2′-2″-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy) as an electron transport material showed maximum luminance of 20,200 cd/m2, maximum efficiency of 11.7 lm/W and maximum external quantum efficiency of 3%. The white emission of Commission Internationale de l'Éclairage chromaticity coordinates was obtained (0.26,0.33).