Tunable color of Ce3+/Tb3+-codoped Ba3Sr4(BO3)3F5 phosphors for near-UV-pumped LEDs

Single-component-tunable blue-to green-light-emitting phosphors Ba3Sr4(BO3)3F5: Ce3+, Tb3+, Na+ (BSBF: Ce3+, Tb3+, Na+) promising for near-UV-pumped light-emitting diodes (LEDs) were synthesized via high-temperature solid-state reactions, and their photoluminescence properties were systematically investigated. Upon the excitation of 360 nm, the BSBF: Ce3+, Tb3+, Na+ phosphors exhibited a broad blue emission band at 422 nm and a series of sharp emission lines at 490, 544, 585, and 623 nm, which originated from the 4f05d1–4f1 transition of Ce3+ ions, and 5D4–7FJ (J = 6, 5, 4, 3) transitions of Tb3+ ions, respectively. Through the resonance-type energy transfer, the varied emitted colors from blue through cyan and eventually to green were achieved by properly tuning the relative dopant composition of Ce3+/Tb3+. Moreover, the energy transfer from Ce3+ to Tb3+ in BSBF host matrix was demonstrated via the dipole–dipole interaction mechanism. Additionally, the critical distances (RC\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ R_{\text{C}} $$\end{document}) calculated by quenching concentration and spectral overlap method in such system were 2.166 and 1.940 nm, and the activation energy for thermal quenching (ΔE) was determined to be 0.117 eV. These results indicate that the developed color-tunable phosphors BSBF: Ce3+, Tb3+, Na+ are competitive as the promising single-component phosphor-converted materials for near-UV-pumped LEDs.