Luminescence mechanism modeling in Eu3+ doped polymethyl methacrylate by microscopic and macroscopic approaches

Abstract

In this work, red emission is obtained from polymethylmethacrylate (PMMA) doped with europium ions (Eu3+) under ultraviolet excitation. PMMA:Eu3+ samples are successfully synthesized by free radical polymerization and characterized by X-ray diffraction (DRX) and photoluminescence spectroscopy. DRX patterns show the amorphous nature of PMMA and the crystalline phase of Eu3+. Optical bands related to Eu3+ in the polymer composites are observed in excitation and emission spectra and are attributed to the corresponding electronic transitions. The interaction between Eu3+ ions is studied through the emission spectra of PMMA:Eu3+ samples with different Eu3+ concentrations under an excitation of 395 nm. Luminescent emission response is analyzed theoretically using rate equation models with macroscopic and microscopic approaches. The numerical solution of the model agrees with the experimental results. The rate equation model considers that the interaction between Eu3+ ions is driven by the direct energy migration (Eu3+ → Eu3+). The Förster distance and the ratio of the pumping rate and the radiative and nonradiative relaxation constant of the PMMA:Eu3+ system are calculated, and it is demonstrated that the energy transfer rate and the quantum efficiency for both approaches agree. The results allow to predict the luminescent behavior of the PMMA:Eu3+ system with different concentrations of Eu3+ ions, and the method described here can be applied to other similar systems.