Dazzling green emission from graphene oxide nanosheet-embedded co-doped Ce3+ and Tb3+:PVA polymer nanocomposites for photonic applications

Abstract

Novel dazzling green emission has been obtained from graphene oxide nanosheet-embedded Ce³⁺ and Tb³⁺:PVA polymer nanocomposites under UV excitation. We have successfully synthesized Tb³⁺:PVA, Ce³⁺ + Tb³⁺:PVA and Ce³⁺ + Tb³⁺ + graphene oxide nanosheet (GO NS):PVA polymer films by the solution casting method. For these polymer films, their XRD and FTIR spectral profiles have been analyzed for structure details and ion–polymer interaction mechanism. Tb³⁺ doped at different concentrations in the PVA polymer films displayed a green emission at 546 nm (⁵D₄ → ⁷F₅) and under 370 nm (⁷F₆ → ⁵L₁₀) excitation. Upon co-doping with Ce³⁺ to the Tb³⁺:PVA polymer film, it exhibits enriched green emission compared to the single Tb³⁺:PVA under the same excitation due to energy transfer from Ce³⁺ to Tb³⁺. Surprisingly a common excitation band has been found at 370 nm for Tb³⁺, Ce³⁺ and the GO NS. After good dispersion of the GO NS in the co-doped Ce³⁺ + Tb³⁺:PVA polymer films, the photoluminescence properties are remarkably enhanced and a prominent green emission is observed at 370 nm. The green emission of Tb³⁺ is significantly enhanced though an efficient energy transfer process from Ce³⁺ to Tb³⁺ and the GO NS to Tb³⁺. A possible energy transfer mechanism is clearly demonstrated by several fluorescence methods and lifetime decay dynamics. From these results, these GO NS-embedded Ce³⁺ + Tb³⁺:PVA polymer films could be suggested as promising candidates for green luminescent materials for photonic devices.