Spectroscopic and theoretical investigation of Pr3+ doped Li2O-ZnO-B2O3 glasses

Advancing glass technology demands more versatile, long-lasting LEDs with high colour quality, efficiency, and durability that meet diverse demands. This innovation drives sustainable energy solutions and opens new possibilities in design and application across industries. Driven by the demand for white LEDs, in the present study, we have prepared Praseodymium (Pr ³⁺)-doped Li ₂O-ZnO-B ₂O ₃ (LZB) glasses using the melt-quenching method and thoroughly investigated their composition-dependent physical, structural, and spectroscopic properties. X-ray diffraction (XRD) confirmed the amorphous nature of the glasses. At the same time, Raman spectroscopy indicated structural changes in the glass network due to Pr ³⁺ incorporation, evidenced by intensity variations and peak shifts. As Pr ³⁺ (Pr ₂O ₃) concentration increased, density and refractive index rose, suggesting denser packing and enhanced polarizability due to the formation of non-bridging oxygens (NBOs) and Pr-O bonds. Optical analysis via UV-Vis-NIR spectroscopy revealed characteristic absorption peaks associated with Pr ³⁺ f-f transitions, with Tauc’s plot showing an indirect band gap between 3.08 and 3.23 eV and an increase in Urbach energy at higher Pr ³⁺ concentrations, indicative of more significant structural disorder. Photoluminescence (PL) studies demonstrated strong emissions in the visible and near-infra-red regions, with notable peaks at 603 nm and 1038 nm, corresponding to the ¹D ₂→ ³H ₄ and ¹D ₂→ ³F ₃ transitions, respectively. These emissions and chromaticity shift from red to green-blue as Pr ³⁺ concentration increases, suggesting potential applications in optical devices such as fibre amplifiers. Judd-Ofelt (J-O) analysis further quantified key parameters like radiative transition probability and stimulated emission cross-section, supporting experimental findings. The investigated results show that 0.1 mol% of Pr ³⁺ is the optimal concentration in an LZB glass matrix with enhanced luminescence beyond which luminescence quenching is observed. The observed quenching at higher concentrations of Pr ³⁺ in the LZB glass matrix is attributed to the increased non-radiative energy transfer among closely packed Pr ³⁺ ions. Hence, LZBPr _0.1 is ideal among all the investigated glasses and finds potential applications in photonics.