In this work,a series of polymer bulk-heterojunctions is fabricated based on the combinations of different donors(Ds)(P3HT and PCPDTBT) and acceptors(As)(PCBM,ICBA,and F8BT).Exciton quenching efficiencies of the D–A pairs are obtained in order to quantify charge-transfer between the donor and the acceptor via a modified approach developed in conjunction with experimental results of optical absorption and photoluminescence spectra.It is discovered that the exciton quenching efficiency in the combination of PCPDTBT:PCBM and P3HT:PCBM reaches 70% and over,but in PCPDTBT:ICBA it is about 12%.A relatively high △LUMOdonor-acceptorresults in a relatively high exciton quenching efficiency,which is responsible for better charge separation.The results agreed well with the photocurrent effect of the heterojunction layers.The work offers a convenient way to predict a potentially promising photovoltaic material with a selected D–A pair.
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.
