Highly thermostable white-emitting Ca9ZnK(PO4)7:Ce3+,Dy3+ single-phase phosphor with tunable photoluminescence and energy transfer

White light-emitting diodes (WLEDs) fabricated with single-phase white phosphor are currently widely used in lighting and displays. Herein, we describe the development of a single-component white-emitting micro-sized powder Ca9ZnK(PO4)7 (CZKP):Ce3+,Dy3+ with high thermal stability. Theoretical and experimental investigations confirmed that the phosphate CZKP with a whitlockite-like structure was suitable as a phosphor host. The photoluminescence of cerium/dysprosium single- and co-doped samples was comprehensively studied. Dipole–dipole interaction resulted in the Ce3+ → Dy3+ energy transfer, which contributed to the spectral regulation for acquiring the white-emitting performance. Moreover, the superior thermal stability of the representative CZKP:0.10Ce3+,0.15Dy3+ phosphor was revealed. Finally, we explored the working performance of single-phase white phosphor-converted WLEDs. The corresponding work shows a successful design for achieving a single-component white phosphor via the Ce3+ → Dy3+ energy transfer approach.