Reduction of self-quenching effect in organic electrophosphorescence emitting devices via the use of sterically hindered spacers in phosphorescence molecules

The reduction of self-quenching effect by introduction of sterically hindered spacers in phosphorescence molecules was analyzed for a electrophosphorescence emitting device. The iridium complex of tris-ortho-cycloetalated compound exhibits a strong green phosphorescence emission with a photoluminescence (PL) quantum yield of 0.71 in solutions and a short lifetime in solids. Self-quenching is reduced significantly due to sterically hindered pinene spacers which provides minimum bimolecular interaction.