Triarylboryl‐Functionalized Oxadiazole as a Host Material with Electron Transporting Property for Green PhOLEDs

Abstract

A triarylboryl‐functionalized oxadiazole compound, 2,5‐bis‐(m‐dimesitylboryl‐phenyl)‐1,3,4‐oxadiazole (1) was prepared and characterized to investigate multi‐functional properties in phosphorescent OLEDs (PhOLEDs). X‐ray crystal structure revealed that two Mes2B groups are oriented toward the same side and the entire fragments of oxadiazole, phenylene, and trigonal boron are in a nearly coplanar arrangement. From the optical and electrochemical measurements, 1 was shown to possess high triplet energy (E T = 2.75 eV) and deep HOMO (E HOMO = 6.02 eV) and low LUMO levels (E LUMO = 2.53 eV), which are suitable for electron transporting (ETM) and/or host materials in PhOLEDs. Green PhOLED devices incorporating 1 as electron transporting material (ETM), host, or host/ETM were fabricated and compared their performance with that of the devices based on the well‐known CBP (9,9′‐(1,1′‐biphenyl)‐4,4′‐diylbis‐9H‐carbazole) host and TPBi (1,3,5‐tris(1‐phenyl‐1H‐benzimidazol‐2‐yl)benzene) ETM. Among them, the devices based on 1 as host/ETM showed the highest performance that is comparable to that of the reference device.