LAUSR

Two new organic small molecules composed of phenanthrene, carbazole and an electron deficient moiety were synthesized by a Suzuki coupling reaction. It is particularly intriguing to compare the electroluminescent (EL) properties of PBBM and PBTZ, which have the same molecular structure with the respective high Td at around 436 °C and 423 °C. By changing the electron deficient moiety of the C9-position of phenanthrene, the photophysical, electrochemical and electroluminescent properties of these two compounds showed significant differences. Furthermore, green and red phosphorescent organic light emitting diodes (OLEDs) employing PBBM and PBTZ as host materials exhibited low efficiency roll-off, and the red OLEDs based on both compounds revealed better EL performance than those of the green OLEDs. Especially, the PBBM-hosted green and red OLEDs achieved a maximum EQE of 14.3% and 18.2%, respectively.