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

The development of phosphors with color-tunable luminescence including white emission is at the forefront of lighting and display technologies. Herein, Dy 3+ ,Tm 3+ single-doped or co-doped K 3 Y(PO 4 ) 2 phosphors are synthesized through the solid-state reaction method. By properly adjusting the ratio of Dy 3+ ,Tm 3+ 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 Tm 3+ and Dy 3+ is further investigated via measuring the luminescence decay curve. Based on efficient energy transfer from Tm 3+ to Dy 3+ , the emission of Dy 3+ exhibits an abnormal thermal enhancement phenomenon as the temperature increases. The optical thermometry behaviors of various emission combinations for the Dy 3+ ,Tm 3+ 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 K 3 Y(PO 4 ) 2 :Tm 3+ ,Dy 3+ phosphors in white LEDs, providing proof-of-concept for the lighting and display fields.