A white light-emitting OLED device including spaced anode and cathode, and having blue light-emitting and yellow, orange, or red light-emitting layers, the blue light-emitting layer including a monoanthracene derivative of Formula (I) as a host material: ##STR00001## wherein R.sub.1-R.sub.8 are H; R.sub.9 is not the same as R.sub.10; R.sub.9 is a naphthyl group having no fused rings with aliphatic carbon ring members; and R.sub.10 is a biphenyl group having no fused rings with aliphatic carbon ring members; provided that R.sub.9 and R.sub.10 are free of amines and sulfur compounds.
A process for improving the stability to photo-oxidation of a polycyclic aromatic compound having at least two polymorphic forms comprises treating a first polymorph with one or more solvents to obtain the more stable second polymorph and then separating the second polymorph from the solvent.
