Stable color-tunable CaY(GaO)(BO):Bi/Tb/Eu phosphors for application in -UV-pumped LEDs.

For further development of light sources, white light-emitting diodes (LEDs) have attracted widespread attention as promising next-generation light sources fabricated the combination of phosphors and LED chips. However, latent defects, such as chemical/thermal instability, low color rendering index (CRI) and high correlated color temperature (CCT), of current mainstream LEDs seriously hinder their further large-scale implementation. Herein, in order to overcome these limitations, single-phase color-tunable gaudefroyite (CaY(GaO)(BO) (CYGB)) tridoped with Bi/Tb/Eu ions was synthesized for the first time and detailed characterisation was performed high-temperature solid-state reaction and structural/spectral analyses, respectively. Radius difference percentage calculations and Rietveld refinements indicate that dopants occupy both Y and Ca sites but preferably the Y site over the Ca site due to the same valence state. Through subtly regulating the (co)doping contents and skillfully utilizing the energy transfer (ET) strategy from the allowed transition of blue light-emitting Bi to the forbidden transition of green/red light-emitting Tb/Eu, the color hue (including white light) of highly efficient PL can be easily tuned according to the need. Meanwhile, composition/content-optimized white light-emitting CYGB:2%Bi/10%Tb/12%Eu also shows splendid chemical/thermal stability. Finally, as a proof-of-concept experiment, the CYGB:2%Bi/10%Tb/12%Eu phosphor-converted LED (pc-LED) was fabricated and encapsulated the up-to-date remote 'capping' method, which imparted attractive performances. Altogether, the stable CYGB:Bi/Tb/Eu phosphor is a promising candidate for application in lighting/display fields.