Single-component full-color emitting Ca6Y2Na2(PO4)6F2:Eu2+,Tb3+,Mn2+ phosphors with superior performance: color-tunable and energy transfer study

Abstract

Highly efficient single-component full-color emitting Ca₆Y₂Na₂(PO₄)₆F₂ (CYNPF):Eu²⁺,Tb³⁺,Mn²⁺ phosphors have been synthesized by a high-temperature solid-state reaction. Coupled with the Eu²⁺, Tb³⁺, and Mn²⁺ emission bands centered at 455 nm, 547 nm, and 580 nm, color-tunable white light can be generated. The energy transfer (ET) process from Eu²⁺ to Tb³⁺ and Mn²⁺ is attributed to the resonant dipole–dipole/dipole–dipole interaction mechanism with ultra-high ET efficiency (>90%). The emission color of the phosphors can be tuned from blue to yellowish green and orange with the corresponding CIE chromaticity coordinates of (0.1719, 0.1215), (0.2852, 0.4289), and (0.4752, 0.3903), respectively. Through controlling the concentration ratio of Tb³⁺ and Mn²⁺ ions, optimal white light emission can be obtained with CIE coordinates of (0.3381, 0.3353) excited at 365 nm, which is very close to the National Television Standards Committee white (0.330, 0.330). The thermal stability of the Eu²⁺, Tb³⁺, and Mn²⁺ codoped CYNPF phosphors has been investigated systematically. A single-component white LED (wLED) device has been fabricated by combining the CYNPF:Eu²⁺,Tb³⁺,Mn²⁺ phosphor with a 365 nm near-ultraviolet (n-UV) LED chip, which exhibits a high color rendering index (R_a = 80.2) along with a low color temperature of 5207 K and CIE coordinates of (0.3212, 0.3221). The results suggest that the phosphors can be used as a candidate material for single-component white phosphors for n-UV excited full-visible-spectrum wLEDs.