Neutralizing the Charge Imbalance Problem in Eu3+-Activated BaAl2O4 Nanophosphors: Theoretical Insights and Experimental Validation Considering K+ Codoping

In recent years, rare-earth-doped nanophosphors have attracted great attention in the field of luminescent materials for advanced solid-state lighting and high-resolution display applications. However, the low efficiency of concurrent red phosphors creates a major bottleneck for easy commercialization of these devices. In this work, intense red-light-emitting K + -codoped BaAl 2 O 4 :Eu 3+ nanophosphors having an average crystallite size of 54 nm were synthesized via a modified sol-gel method. The derived nanophosphors exhibit strong red emission produced by the 5 D 0 → 7 F J ( J = 0, 1, 2, 3, 4) transitions of Eu 3+ upon UV and low-voltage electron beam excitation. Comparative photoluminescence (PL) analysis is executed for Eu 3+ -activated and K + -coactivated BaAl 2 O 4 :Eu 3+ nanophosphors, demonstrating remarkable enhancement in PL intensity as well as thermal stability due to K + codoping. The origin of this PL enhancement is also analyzed from first-principles calculations using density functional theory. Achievement of charge compensation with the addition of a K + coactivator plays an important role in increasing the radiative lifetime and color purity of the codoped nanophosphors. Obtained results substantially approve the promising prospects of this nanophosphor in the promptly growing field of solid-state lighting and field emission display devices.