Tunable luminescence from Bi³⁺ sensitized La₂ Zr₂ O₇ :Eu³⁺ red nanophosphors for display applications

Bismuth ion (Bi³⁺ ) sensitized, europium ion (Eu³⁺ ) activated La₂ Zr₂ O₇ nanophosphors are prepared successfully by simple wet chemical method. Strong blue emission of singly doped La₂ Zr₂ O₇ with Bi³⁺ was observed at 310 nm excitation, its wide emission spectrum has a peak maximum at 465 nm ascribed to electronic transition ³ P₁  → ¹ S₀ of Bi³⁺ . The recorded photoluminescence spectra of y at% Eu³⁺ codoped La₂ Zr₂ O₇ , when excited at 285 nm, the emission spectrum exhibits maximum peaks at wavelength values 615 nm, 646 nm and 665 nm which are ascribed to ⁵ D₀  → ⁷ F₂ , ⁵ D₀  → ⁷ F₃ and ⁵ D₀  → ⁷ F₄ transitions of Eu³⁺ respectively. The chromaticity coordinates for the optimized sample were found to be (0.519, 0.329). Sensitizing with Bi³⁺ can affect the luminescence properties of La₂ Zr₂ O₇ :Eu³⁺ phosphors. With reference to the change in Eu³⁺ concentration from Y  = 1, 2, 3, 4 and 5%, color tunable luminescence from blue to orange, red of La₂ Zr₂ O₇ :Bi³⁺ ,Eu³⁺ phosphors are observed. The lifetime decay values, energy level description and CIE chromatic color coordinates for Bi³⁺ , Eu³⁺ in La₂ Zr₂ O₇ :Bi³⁺ ,Eu³⁺ codoped sample was discussed. The spectral overlap between sensitizer, activator ions confirms the efficient energy transfer from Bi³⁺ to Eu³⁺ in La₂ Zr₂ O₇ :Bi³⁺ ,Eu³⁺ codoped sample and is via a dipole-quadruple mechanism.