Insights into structural, luminescence and temperature-dependent emission characteristics of Ca2Al2O5:Dy3+ phosphors for advanced lighting applications

Abstract

This research synthesized and thoroughly examined novel Ca₂Al₂O₅:Dy³⁺ phosphors to assess their potential for solid-state lighting and temperature-sensing applications. X-ray diffraction (XRD) verified the formation of a cubic phase with Dy³⁺ ions successfully integrated into the Ca₂Al₂O₅ host lattice. Photoluminescence (PL) analysis showed distinct blue (483 nm), yellow (575 nm), and weak red (663 nm) emissions, corresponding to the ⁴F_9/2 → ⁶H_15/2, ⁴F_9/2 → ⁶H_13/2, and ⁴F_9/2 → ⁶H_11/2 transitions of Dy³⁺, respectively. The study identified that a 2 mol% concentration of Dy³⁺ is the ideal doping to achieve optimal luminescence, and the emission falls in the cool white light region. The optical study was used to ascertain the optical band gap, and the band gap of the host matrix decreases upon doping (from 5.01 eV to 4.83 eV) as new defect energy levels appear between the valence band and the conduction band. Temperature-dependent photoluminescence (TDPL) studies demonstrated excellent thermal stability, with the phosphors retaining significant luminescence intensity even at elevated temperatures. These phosphors exhibit appreciable thermal quenching behaviour and possess an activation energy of 0.20051 eV, underscoring their resilience at high temperatures. These results highlight the promising optical performance and thermal durability of Ca₂Al₂O₅:Dy³⁺ phosphors, making them strong candidates for white LEDs and temperature-sensitive optoelectronic devices.