Color-tunability and energy transfer of a highly thermal-stable BaZnB4O8:Tb3+/Eu3+ phosphor for single-component w-LEDs

A series of Tb3+ single-doped and Tb3+/Eu3+ co-doped BaZnB4O8 samples with color tuning were efficiently synthesized using the solid-state reaction method. The crystal structure, photoluminescence and the energy transfer process (ET) of the samples were systematically studied. The optimal BaZnB4O8:0.08Tb3+ sample shows efficient green emission, then tunable color was achieved by merely introducing a few of Eu3+ ions owing to the highly efficient ET process from Tb3+ to Eu3+ in the BaZnB4O8:0.08Tb3+/yEu3+ samples. The ET efficiency from Tb3+ to Eu3+ of the BaZnB4O8:0.08Tb3+, yEu3+ samples rose from 32.1% to 51.6%, simultaneously the luminescent quantum yield improved from 24.7% to 36.8%, as the Eu3+ doping concentration increased from 0.125% to 2%. Moreover, the Tb3+/Eu3+ co-doped samples exhibited great thermal stability, keeping about 90.2% (@150°C) of their original intensity at room temperature. Finally, white light was achieved by a warm w-LEDs fabricated by coating the BaZnB4O8:0.08Tb3+, 0.0025Eu3+ sample on a 365 nm chip. The w-LEDs showed outstanding performance characteristics, with a CCT of 3869 K and a CRI of 89.3. According to the results, Tb3+/Eu3+ co-doped BaZnB4O8 samples have the potential to serve as single-component multicolor-emitting or white-emitting phosphors upon excitation at near-UV wavelength.