In this work,we report the preparation of a series of electroluminescent(EL)devices based on a high-performance polymer,poly(p-phenylene benzobisoxazole)(PBO),and their optoelectronic properties,which have been rarely explored.The device structure is optimised using a complex cathode structure of tris-(8-hydoxyquinoline)aluminium(Alq3)/LiF/Al.By tuning the thickness of the Alq3layer,we improve the device efficiency dramatically in an optimized condition.Further analysis reveals that the Alq3layer in the complex cathode structure acts as a hole blocker in addition to its electron-injection role.A green light emission with a maximum brightness of 8.7×103cd/m2and a moderate current efficiency of 4.8 cd/A is obtained.These values are the highest ever reported for PBO devices.The high operational stability demonstrated by the present device makes it a promising tool for display and lighting applications.A new material is added to the selection of polymers used in this field up to now.
