Cyan to orange color tunable emitting of Ca₂GdHf₂Al₃O₁₂: Ce³⁺, Mn²⁺ phosphors via energy transfer

Recently, the realization of spectrum-tunable single-phase phosphors has become the focus of phosphor-converted light-emitting diodes (pc-LEDs) research. Herein, a novel color-tunable Ca₂GdHf₂Al₃O₁₂ (CGHAO): Ce³⁺, Mn²⁺ single-phase phosphor was prepared. A thorough investigation was conducted into the crystal structure, site occupancy, morphology, luminescent characteristics, energy transfer (ET) process, and thermal quenching. These phosphors show broadband excitation between 200 and 460 nm matching commercially available near-ultraviolet LED chips (380–420 nm). The ratio of dopant ion concentration can be varied to achieve cyan-to-orange chromaticity adjustment due to the Ce³⁺ → Mn²⁺ effective ET. By confirming that the ET mechanism is controlled by dipole-quadrupole interaction with 42.64 % efficiency. In particular, under excitation at 405 nm, the optimal sample CGHAO: 5%Ce³⁺, 15%Mn²⁺ emits bright yellow light with an IQE of 84.35 %, and has good thermal (E_a = 0.271 eV) and chromatic stability (ΔE = 1.35 × 10⁻² at 473K). Based on these findings, color-tunable CGHAO: Ce³⁺, Mn²⁺ phosphor could be considered potential candidates for pc-LEDs device applications.