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

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 (D-5(4) -> F-7(5)) and under 370 nm (F-7(6) -> L-5(10)) 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.