Erbium(III)-doped polyurethaneureas: novel broadband ultraviolet-to-visible converters

Abstract

Novel, polymeric UV-to-visible converters were prepared by doping elastomeric poly(ether-urethaneurea) copolymers with 5–25% by weight of ErCl3 6H2O, corresponding to Er3+ concentrations of 2.19 to 10.86% by weight. When excited in the UV at 355 nm, the doped films generated a very broad, continuous visible luminescence between 400 and 750 nm. Preparation and spectroscopic characterization of the samples are discussed in detail. The color coordinates, color temperature, color rendering index of the samples, and the degree of overlap of their emission bands with the spectral response of the eye were determined. The color rendering index of samples is in the 57–70 range. The sample containing 2.19% by weight of Er3+ was found to give the color coordinates closest to the white-source region and the highest color rendering index. The color temperatures of the samples were in the 5093–5540 K range. Overlap between the emission bands and the spectral response of the eye improved with increasing erbium concentration.