Optimization of NIR photoluminescence properties of Er3+/Yb3+-doped PEO/PVP blended composites

Abstract

Er3+-doped and co-doped (Er3+/Yb3+):polyethylene oxide (PEO)/polyvinylpyrrolidone (PVP) blended polymer composites were synthesized by the traditional solution-casting method. The amorphous nature of the prepared Er3+- and Yb3+-doped polymer composites was confirmed by X-ray diffraction analysis. The interaction between dopant rare earth ions and the blended polymer was systematically elucidated by Fourier transform infrared spectroscopy and Raman spectroscopy analysis. A prominent near-infrared (NIR) emission was observed at 1.53 μm (4I13/2→4I15/2) from the fluorescence spectra of the Er3+:PEO/PVP polymer composites under 980 nm excitation at room temperature. The NIR emission intensity was appreciably increased by increasing the Er3+ ion concentration. The optimized concentration of the Er3+ ions was found to be 0.2 wt%. The emission performance was drastically reduced after the optimized concentration due to the concentration quenching effect. Upon co-doping with Yb3+ to Er3+:PEO/PVP polymer composites, the NIR emission intensity at 1.53 μm (4I13/2→4I15/2) was remarkably improved through energy transfer from Yb3+ to Er3+. The Er3+ NIR fluorescence intensity was increased significantly by increasing the co-doping concentration of Yb3+ in the PEO/PVP polymer composite system. The optimized sensitizing concentration of Yb3+ ions was found to be 0.05 wt% in the PEO/PVP polymer-blended composite system. The energy-transfer phenomenon was elucidated through an energy-level diagram. These co-doped (0.2Er3++0.05Yb3+):PEO/PVP polymer-blended composite materials could be considered as promising candidates for several NIR photonic device applications. This approach of NIR-emitting polymer composites will be useful for various NIR optoelectronic applications.