Poly(fluorene-oxadiazole) copolymer-based light-emitting devices on a plastic substrate

We reported on one new series of light-emitting copolymers for polymer light-emitting devices (PLEDs), poly(dioctyl fluorene-co-diphenyl oxadiazole)s (P(DOF-DPO)s). The device structure used in this study was composed of: indium tin oxide (ITO) anode/PEDOT:PSS ((polyethvlenedioxythiophene)-poly(styrene sulfonate)) as hole-transporting layer/P(DOF) or P(DOF-DPO) as emissive layer/calcium + aluminum cathode. Both the photo-luminescence spectra and electro-luminescence spectra were slightly blue-shifted, when we added less than 10% DPO moiety into P(DOF-DPO). The maximum emission efficiency of the PLEDs based on P(DOF-DPO) with less than 10% DPO moiety are comparable to the P(DOF)-based PLEDs. However, when we added more than 20% DPO moiety into P(DOF-DPO), we found that P(DOF-DPO) PLEDs had significantly lower device efficiency than P(DOF) (poly(dioctyl fluorene)) PLEDs.