Unrevealing the opto-structural features of luminescent polymeric films containing EuIII-doped phosphors through spectroscopic and theoretical perspectives

Abstract

Tailoring the opto-structural properties of lanthanide (Ln^III)-doped phosphors dispersed in polymeric matrices through classical spectroscopic characterization is challenging due to their composite nature. To overcome this issue, a combination of experimental and theoretical methods can bring additional opportunities to understand the interactions at the phosphor–polymer interface at the molecular level. In this scenario, the SrY₂O₄:Ce^III/IV,Eu^III/PMMA (poly(methyl)methacrylate – PMMA) red-emitting film is deeply investigated by combining experimental spectroscopic measurements with an adapted low-cost computational approach. This theoretical methodology is based on (i) structural optimization using a quantum chemical tight-binding model, (ii) obtention of the force constants applying the Hellmann–Feynman theorem, and (iii) calculation of the Ln^III photophysical properties using the simple overlap and bond overlap model using the force constants while fitting the effective polarizability. As a result, the theoretical analysis elucidated the phosphor/polymer surface interactions, illustrating the polymer groups (methyl and ester) in the Eu^III surroundings, and the structural deformities in the composite moieties. These distortions led to changes in the photophysical parameters by varying the phosphor/PMMA proportion. Therefore, this protocol contributes to a better understanding of the opto-structural features of Ln^III-based films, bridging the gap between the experimental results and the strategies to enhance their performance.