Color-tunable luminescence based on the efficient energy transfer of a Tm–Dy system for optical thermometry and white LED lighting

Abstract

The development of phosphors with color-tunable luminescence including white emission is at the forefront of lighting and display technologies. Herein, Dy³⁺,Tm³⁺ single-doped or co-doped K₃Y(PO₄)₂ phosphors are synthesized through the solid-state reaction method. By properly adjusting the ratio of Dy³⁺,Tm³⁺ co-doping concentrations, color-tunable luminescence from blue to yellow, including white luminescence, is realized under 359 nm excitation. The mechanism of energy transfer between Tm³⁺ and Dy³⁺ is further investigated via measuring the luminescence decay curve. Based on efficient energy transfer from Tm³⁺ to Dy³⁺, the emission of Dy³⁺ exhibits an abnormal thermal enhancement phenomenon as the temperature increases. The optical thermometry behaviors of various emission combinations for the Dy³⁺,Tm³⁺ co-doped system are analyzed. The maximum sensitivity can be obtained as a constant of 4.8 × 10⁻³ K⁻¹, which is conducive to improve the measurement accuracy of optical temperature sensing at high temperatures. Furthermore, we also demonstrate the applicability of K₃Y(PO₄)₂:Tm³⁺,Dy³⁺ phosphors in white LEDs, providing proof-of-concept for the lighting and display fields.