Synthesis And Study Of Steric Hindrance Small Molecules Host Materials And Interface Materials Based On Phosphonate Group

Since C.W Tang invented multilayer organic light emitting diodes （OLEDs） in1987,many researchers have made great efforts to enhance the efficiency. Because the singletenergy and triplet energy of the phosphorescent light-emitting diodes devoted tolight-emitting at the same time, the internal quantum efficiency may achieve100％theoretically, it has a broad application prospect in solid state light field and full color displayfield. Phosphonate materials of interfacial modification could reduce the barrier potentialbetween metal electrode and organic materials, reduce the difficulty of electron injection, andresult in enhancing the efficiency of the devices. In this paper, several host materials andPhosphonate materials of interfacial modification had been synthesized and characterized, thedevices showed excellent performance. The related points of view is summarized as followed:1. By means of Friedel-crafts reaction, three fluorenyl small molecule host materials ofsteric named F3BCz2,F3OCz2, and F3OF2had been synthesized and characterized. Thedevices with F3BCz2,F3OCz2, and F3OF2as host materials of gree, red and blue PhOLEDsrespectively showed good performance. The maximum current efficiency of the device withF3OF2: Tris（2-phenylpyridine） iridium（III）[Ir（ppy）₃] as emission layer（EML） achieved50.1cd/A.2. In order to balance the injection and the transportation of the charge carriers, wedesigned and synthesized a new butterfly bipolar small molecule host material namedDBCzDPOCz. The maximum current efficiency of the device with DBCzDPOCz: Ir（mppy）₃as EML achieved27.4cd/A, which is9cd/A higher than that of device with PVK:Ir（mppy）₃as EML, and the turn-on voltage is4.2V, which is3.8V lower than that of the device withPVK:Ir（mppy）₃as EML.3. In order to reduce the barrier potential between metal electrode and organic materials,we synthesized two phosphonate small molecular interfacial modification materials nameTPP-3FEP and TPZ-3FEP, the device with TPP-3FEP or TPZ-3FEP as cathode interlayershowed better performance than those of the traditional device with barium as cathodeinterlayer.