ckness of from about 10 microns to about 40 microns, include molecules of the followingformula: ##STR1## dispersed in a highly insulating and transparent organic resinous binder wherein X is an alkyl group or a halogen, especially those substituents selected from the group consisting of (ortho) CH.sup.3, (para) CH.sup.3, (ortho) CL, (meta)CL, and (para) CL.Examples of specific aryl amines are N,N'