Abstract: Novel Y$_{1 - x - y}$VO$_{4}$:$x$Dy$^{3 + }$, $y$Bi$^{3 + }$ ($0.01 \le x \le 0.05, 0 \le y \le 0.20$) phosphors for light emitting diode (LED) were successfully synthesised by solid-state reaction. The calculation results of electronic structure show that YVO$_{4}$ has a direct band gap with 3 eV at $G$. The top of the valence band is dominated by O 2p state and the bottom of the conduction band is mainly composed of O 2p and V 3d states. An efficient yellow emission under near-ultraviolet (365 nm) excitation is observed. Compared with the pure YVO$_{4}$:Dy$^{3 + }$ samples, the Dy$^{3 + }$, Bi$^{3 + }$ co-doped samples show a more intensive emission peak (at 574 nm) and a new broad emission band (450--770 nm), due to the $^{4}F_{9 / 2}-{}^{6}H_{13 / 2 }$ transition of Dy$^{3 + }$ and the emission of the VO$_{4}^{3 - }-$Bi$^{3 + }$ complex respectively. The optimum chromaticity index of Y$_{1 - x - y}$VO$_{4}$:$x$Dy$^{3 + }$, $y$Bi$^{3 + }$ ($0.01 \le x \le 0.05, 0 \le y \le 0.20$) is (0.447, 0.497), which indicates that YVO$_{4}$:Dy$^{3 + }$, Bi$^{3 + }$ has higher colour saturation than the commercial phosphor YAG: Ce$^{3 + }$. The effects of concentration of Dy$^{3 + }$, Bi$^{3 + }$, electric states and the photoluminescence properties are discussed in details.

Key words: phosphor, light-emitting diode, vanadate