Electroluminescent bipolar compounds containing quinoxaline or pyridopyrazine and triarylamine segments

Abstract

Dipolar compounds containing both quinoxaline/pyridopyrazine acceptors and arylamine/carbazole donors have been prepared by palladium catalyzed C–C coupling (Stille) reactions in good yields and have been characterized by spectroscopic, electrochemical and thermal methods. The charge transfer character of these molecules can be changed by modification of the acceptor or donor ends. They are green emitting with moderate quantum yields in toluene solutions. However, in dichloromethane the emission maximum is red shifted and the quantum yield diminishes appreciably. High glass transition temperatures were realized for these compounds (143–162 °C). The quinoxaline derivatives effectively function as a hole-transporting and emitting layer in yellow/orange emitting double layer electroluminescent devices. We also demonstrate the possibility of using these materials in single layer devices.