A novel scheme to obtain tunable fluorescent colors based on electrospun composite nanofibers

Europium complexes Eu(BA)₃phen (BA = benzoic acid, phen = 1,10-phenanthroline) and Terbium complexes Tb(BA)₃phen are incorporated into polyvinyl pyrrolidone (PVP) and electrospun into [Eu(BA)₃phen + Tb(BA)₃phen]/PVP composite nanofibers. The morphologies and properties of the final products are investigated via scanning electron microscopy, energy dispersive spectrometry,X-ray powder diffractometry, fluorescence spectroscopy, Fourier-transform infrared spectroscopy and thermogravimetry. The diameter of the composite nanofibers is 431.55 ± 3.14 nm. The obtained composite nanofibers are amorphous in structure and stable below 220 °C. By adjusting the ratio of Eu(BA)₃phen to Tb(BA)₃phen complexes, the fluorescence color of composite nanofibers can be tuned from red to yellow, yellow green, and green under the excitation of 276-nm single-wavelength ultraviolet light. Besides, the fluorescence lifetime of Eu³⁺ ions in composite nanofibers is extended gradually, while that of Tb³⁺ ions is decreased slowly with increase of Tb(BA)₃phen content. The novel color-tunable composite nanofibers have potential applications in the fields of optical devices, color displays and sensor systems.