Bright green emission from f-MWCNT embedded co-doped Bi3+ + Tb3+:polyvinyl alcohol polymer nanocomposites for photonic applications

Abstract

A bright, dazzling green emission has been obtained from functionalized multi walled carbon nanotube (f-MWCNTs)-embedded Bi3+ + Tb3+:PVA polymer nanocomposites under UV excitation. We successfully synthesized Tb3+:PVA, Bi3+ + Tb3+:PVA and Bi3+ + Tb3+ + f-MWCNTs:PVA polymer films by a solution casting method. For these polymer films, their XRD and FTIR spectral profiles were analyzed for structural details and ion-polymer interaction mechanism. Tb3+ doped at different concentrations in PVA polymer films displayed a green emission at 546 nm (5D4 →7F5) under 370 nm (7F6 →5L10) excitation. Upon co-doping with Bi3+ in the Tb3+:PVA polymer film, the film exhibits enriched green emission compared to single Tb3+:PVA under 320 nm excitation due to the energy transfer from Bi3+ to Tb3+. Surprisingly, a common excitation band was found at 320 nm for Tb3+, Bi3+ and f-MWCNTs. After dispersion of the f-MWCNTs in the co-doped Bi3++Tb3+:PVA polymer films, the photoluminescence properties were remarkably enhanced, and a prominent green emission was observed at 546 nm. The green emission of Tb3+ is significantly enhanced though an efficient energy transfer process from Bi3+ to Tb3+ and f-MWCNTs to Tb3+. The possible energy transfer mechanism was clearly demonstrated via several fluorescent methods. The energy transfer mechanism was substantiated with fluorescence lifetime decay dynamics. From these results, these f-MWCNTs-embedded Bi3++Tb3+:PVA polymer films could be suggested as promising candidates for green luminescent materials for photonic devices.