The effect of polymer Molecular weight and Coumarin 6 - solvent interaction on photoluminescence spectra

摘要

In this article the effect of molecular weight of polyvinylcarbazol (PVK) on the photoluminescence (PL) spectra of the solution of Coumarin 6 (C6) dye and the polymer in their common solvent and also thin film of PVK and the dye is studied. By adding PVK to the C6 solution in dichloroethane, an extra peak was observed in the PL spectra of the solution. The extra peak was more intense when high molecular weight PVK was used as compared with using the low molecular weight polymer. Therefore in each polymer-dye solution, two peaks were detected in their photoluminescence spectrum. The first peak is attributed to C_6 emission and the second one may be related to the interaction of the C6 molecules with the solution of PVK in dichloroethane. This effect was only observed at low concentration of C6. At high concentration of C_6, excimer emission dominates PL spectra and results in a red shift for both peaks. At higher concentrations, only one peak was observable and the excimer emission is stronger than that of lower concentrations. In this case only one peak was observed.