Tunable photoluminescence and energy transfer of YBO 3:Tb 3+, Eu 3+ for white light emitting diodes

Abstract

Rare-earth (Eu ³⁺, Tb ³⁺) ion co-doped YBO ₃ phosphors with a morphology of uniform flower-like assembly are fabricated by a facile hydrothermal method without the use of surfactant, organic ligands, or further sintering treatment. Photoluminescence (PL) studies have demonstrated that under the excitation of 365 nm ultraviolet (UV) light, YBO ₃:Tb ³⁺, Eu ³⁺ emits a white light, including three emissions: a blue band attributed to self-trapped excitons (STEs), a green band due to the Tb ³⁺ transition of ⁵D ₄– ⁷F _j ( j = 6, 5, 4, and 3), and a red band due to the Eu ³⁺ transition of ⁵D ₀– ⁷F _j ( j = 0, 1, 2, 3, and 4). Energy transfers from host YBO ₃ to Tb ³⁺, and Eu ³⁺ and Tb ³⁺ to Eu ³⁺, as well as tunable emission by varying the relative doping ratios are demonstrated. The combination of blue emission from STEs with green and red emissions from activators provides a novel and efficient technique to make white light emitting diodes (WLEDs).