Small organic molecules based on oxazole/thiazole with excellent performances in green and red phosphorescent organic light-emitting diodes†
Four pure organic molecules based on oxazole/thiazole were designed and characterized, and their relevant thermal, photophysical and electrochemical properties were fully investigated. These compounds (2a–2d) exhibited good thermal stabilities, with endothermic glass transitions over 120 °C, the largest of which was 2d with the endothermic glass transition of 145 °C. Four green devices, in which 2a–2d served as host materials, were fabricated and the device based on compound 2d exhibited the best performance with a maximum current efficiency of 50.7 cd A−1 and maximum power efficiency of 50.1 lm W−1. A red device based on 2d was also fabricated, which displayed a maximum current efficiency of 18.7 cd A−1 and maximum power efficiency of 17.3 lm W−1. The excellent performances of 2a–2d make them promising alternatives for efficient green and red devices.