Functionalized Pentacene Derivatives for Use as Red Emitters in Organic Light-Emitting Diodes

Abstract

A series of three pentacene derivatives featuring substituted aryl groups at the 6,13-position, namely, 6,13-diphenylpentacene, 6,13-bis(2,6-dimethylphenyl)pentacene, and 6,13-bis(4-tert-butylphenyl)pentacene, have been synthesized and characterized. The optical properties of each compound have been determined in solution and in the solid state. Films containing the pentacene derivatives dispersed in tris(quinolin-8-olato)aluminum(III) (Alq3) emit in the red with small contribution from the Alq3 host, signaling efficient energy transfer from host to guest molecules. The absolute photoluminescence quantum yield (φPL) of composite films is ∼30−32% at optimum dopant concentration. Organic light-emitting diodes based on these composite films as the active emitting layers have been fabricated and characterized. External electroluminescence quantum efficiencies near the theoretical limit have been achieved.