Reddish-Orange Light Emission in Eu3+ Doped and Dy3+/Eu3+ Codoped lithium Tetraborate Glasses for Solid-State Lighting Devices

Abstract

The spectroscopic analysis of singly doped Eu³⁺ and codoped Dy³⁺/Eu³⁺ lithium tetraborate (LiTeBo) glasses has been carried out to explore the effects of various alkaline earth and alkali components. The analysis involved techniques such as XRD, SEM, FTIR, optical absorption, photoluminescence, and decay spectral profiles. From the optical absorption spectra of Eu³⁺ doped glasses, the bonding properties, optical energy band gaps, nephlauxetic ratios, and Urbach energies were obtained. From the emission spectra, color coordinates, correlated color temperatures, and color purities were obtained. The occurrence of energy transfer from Dy³⁺ to Eu³⁺ is confirmed across all glass samples by analyzing the emission spectra, assessing the overlap in the spectral regions between the Eu³⁺ excitation and Dy³⁺ emission, and evaluating the fluorescence decay curves. The emission spectra of glasses codoped with Dy³⁺/Eu³⁺ ions provided excitation wavelengths, 350, 364, 387 and 394 nm. From the emission transitions, the transitions originated from ⁴F_9/2 to ⁶H_13/2, ⁶H_15/2 of Dy³⁺ ion, and from ⁵D₀ to ⁷F₂ of Eu³⁺ ion indicate the creation of reddish-orange light. The CIE chromaticity coordinates shift from reddish to reddish-orange color along with the excitation wavelengths 350, 364, 387 and 394 nm.