Miscibility effect on the energy transfer induced luminescence enhancement of polyimide/PVK blends

Two series of polyimides exhibiting red light luminescence were synthesized. The energy transfer between poly(N-vinylcarbazole) (PVK) and polyimide enhances the red light luminescence of the polyimide. Meanwhile, the purplish blue light luminescence of the pure PVK polymer was not or hardly observed in the light luminescence spectra of the polyimide/PVK blend depending on the composition of the blend. There was more spectral overlap between the PL emission of PVK and the absorption of the pyromellitic dianhydride (PMDA)-2,7-diaminofluorene (DAF) polyimide than that of the PMDA-3.7-diamino-2.8-dimethyldibenzo-thiophene sulfone (DAS) polyimide. Therefore, the PMDA-DAF polyimide/PVK blends that showed complete energy transfer exhibited the emission spectrum mostly from the polyimide. Incorporating a modified silicone surfactant further showed remarkable enhancement of the red luminescence by improving the miscibility of the blends of PMDA-DAF polyimide with PVK.