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

Abstract

Evaluating opto-structural correlations to tailor the luminescence of polymeric films based on Eu III -doped phosphors using a new combined spectroscopic and theoretical protocol. 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 SrY 2 O 4 :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.