Efficient Ce3+ → Tb3+ energy transfer pairs with thermal stability and internal quantum efficiency close to unity

Abstract

The exploitation of functional phosphors possessing a variety of advantages, including narrow-band emission, fast response to near-ultraviolet (n-UV)/blue light excitation, high quantum efficiency, and low thermal quenching, is essentially important for the wide-color-gamut display backlights. It is the first example to introduce Ce³⁺–Tb³⁺ pairs into the Ca₃Lu₂Si₆O₁₈ (CLSO) host for identifying a novel green-emitting material with all the mentioned properties. The efficient Ce³⁺ → Tb³⁺ energy transfer process was monitored in the CLSO host via dipole-quadruple interactions between Ce³⁺ and Tb³⁺ ions, leading to a wide excitation band in the n-UV region and bright green light with a main sharp emission band at 543 nm. Moreover, the composition-optimized sample has been found to achieve extremely high internal quantum efficiency (close to unity) and excellent thermal stability (lost only 13.2% of the initial emission intensity at 150 °C), which are more favorable than those shown by a vast majority of green-emitting phosphors reported recently. The prototype pc-WLED fabricated using the as-prepared sample as the green component exhibited a high luminous efficiency (LE) of 31.48 lm W⁻¹ and a wide color gamut of 91.2% (area ratio) National Television Standards Committee (NTSC) 1953 standard. These attractive properties verified that the proof of concept concerning the designed sample will be a promising candidate to substitute the current green color phosphors for wide-color-gamut display backlights.