Organic light emitting host materials

A compound represented by the formula:

• where R1, R2, R3, R4, R5 and R6 are independently H, C1-C3 alkyl, or C1-3 perfluoroalkyl;
• HT is optionally substituted carbazoyl, optionally substituted phenylnaphthylamine, or optionally substituted diphenylamine, where each m is independently 0, 1, or 2;
• and ET is selected from optionally substituted benzimidazol-2-yl, optionally substituted benzothiazol-2-yl, optionally substituted benzoxazol-2-yl, optionally substituted 3,3′-bipyridin-5-yl, optionally substituted quinolin-8-yl, optionally substituted quinolin-5-yl, and optionally substituted quinoxalin-5-yl, where n is 1 or 2.