Platinum (ii) schiff base complexes with increased emission quantum yield for red oled applications

An OLED emitter having a chemical structure of Structure I:

• where Pt is in the oxidation state of II complexed to a tetradentate ligand where:
• X1-X4 are independently carbon, nitrogen, silicon or phosphorous;
• R1-R12 are independently selected from hydrogen, halogen, hydroxyl, unsubstituted alkyl, substituted alkyl, cycloalkyl, unsubstituted aryl, substituted aryl, acyl, alkoxy, acyloxy, amino, nitro, acylamino, aralkyl, cyano, carboxyl, thio, styryl, aminocarbonyl, carbamoyl, aryloxycarbonyl, phenoxycarbonyl, or alkoxycarbonyl;
• and E is an emission intensity enhancement group comprising an aromatic group conjugated to the ligand's phenyl groups, and, optionally, where adjacent R1-R12 and E groups are independently combined in a 5-8 member ring, and R1, R2, R11 and R12 are not amino or a portion of a substituted nitrogen heterocyclic aromatic.