Optical Characteristics of Dy3+ Ions in Alkali Fluoroborate Glasses for WLEDs

Abstract

The aim of this study is to synthesize and characterize an economical alkali fluoroborate glass doped with Dy3+ ions using melt quenching technique for white light generation applications. The glasses under investigation are prepared from the precursor mixture keeping the molar composition 10K2O + 10BaO + 10ZnF2 + (70-x)B2O3 + xDy2O3, where x = 0.1 mol.%, 0.5 mol.%, 1.0 mol.%, 1.5 mol.% and 2.0 mol.%. Optical characterization techniques such as absorption, photoluminescence excitation, emission and decay analysis were accomplished to validate the use of the prepared glasses for white light emitting diodes. Optical band gap energy and vital Judd–Ofelt (JO) intensity parameters were derived using the absorption spectrum. The JO intensity parameters were used to explore some characteristic radiative parameters of the present glass system. The photoluminescence spectra of the glasses have been recorded at an excitation wavelength of 348 nm and the spectra contain two intense emission bands in the blue (480 nm) and yellow (572 nm) regions and a weak band in the red region (664 nm). With the increase of dopant ion concentration, the intensity of all emission bands marked a gradual increase. The variation of the ratio of integrated intensity of yellow band to blue band (Y/B ratio) with the concentration of Dy2O3 is also studied. Color coordinates determined using commission international de l’eclairage (CIE) 1931 suggest that the prepared glass can be a potential material for white light applications. The experimental lifetime values marked a significant decrease with increase in dopant ion concentration and the mechanism responsible for the quenching is identified. Quantum yield is determined experimentally as well as using JO theory.