Synthesis, structure, and color-tunable luminescence properties of lanthanide activator ions doped bismuth silicate as single-phase white light emitting phosphors

Abstract

A series of lanthanide activator ions (Ln3+) doped bismuth silicate Bi4Si3O12 phosphors have been fabricated via the Pechini sol−gel route. The as-synthesized eulytite structured Bi4Si3O12 sample which exhibits intense green-blue emission is beneficial for host materials of lanthanide activator ions. When the Ln3+ ions (Sm3+, Dy3+, or Eu3+) are doped into the Bi4Si3O12 host, an insufficient energy transfer occurs from the host matrix to Ln3+ ions, which can be confirmed by the photoluminescence spectra and decay lifetimes of the Ln3+ doped samples. The as-synthesized Bi4Si3O12:Ln3+ phosphors show both the intrinsic broad band luminescence of Bi4Si3O12 host and the characteristic sharp peak emissions of Ln3+ ions, which can generate the tunable multicolor emissions in a single-phase phosphor by adjusting the Ln3+ doping concentrations. More importantly, three kinds of Ln3+-doped single-phase white light emitting phosphors with excellent chromaticity coordinate (x, y) and CCT in the warm white region [Sm3+: (0.336, 0.330), 5315 K; Dy3+: (0.330, 0.370), 5614 K; Eu3+: (0.340, 0.307), 5034 K] can be obtained when the doping concentrations of Sm3+, Dy3+, and Eu3+ are fixed at 0.5, 5, and 1 mol%, which are quite close to the daily use of pure white light. By integrating the Bi4Si3O12:Ln3+ phosphors into a 280 nm UV LED chip, all the fabricated WLED devices can exhibit bright white light emission, which provides direct evidence that the as-synthesized BSO:Ln3+ (Ln = Sm, Dy, and Eu) single-phase white-emitting phosphors have great potential for WLEDs and optoelectronic devices.