Synthesis and photoluminescence properties of Eu-activated LiCaZnVO white-emitting phosphors.

Single-component white-emitting phosphors are highly promising for applications in phosphor-converted white light-emitting diodes. In this paper, novel single-phase LiCaZnVO:Eu ( = 0-0.05) phosphors with tunable white emissions were prepared by a conventional solid-state reaction. The LiCaZnVO ( = 0) phosphor showed an efficient self-activated bluish-green emission due to the V-O charge transfer transition of the [VO] groups, and possessed an intense broad excitation spectrum in the 250-400 nm wavelength range. Together with the [VO] emission, the red emission of Eu ions was also observed in LiCaZnVO:Eu phosphors. The energy transfer from the [VO] groups to the Eu ions was studied. Importantly, the emission colors of LiCaZnVO:Eu phosphors varied from greenish-blue to whitish and then to red with increasing Eu content and the white-light emission was realized in the single-phase phosphor of LiCaZnVO:0.003Eu by combining the [VO]-emission and the Eu-emission. The energy-transfer efficiency from [VO] groups to Eu ions in the LiCaZnVO:0.003Eu sample was determined to be about 52% and the internal quantum efficiency of the LiCaZnVO:0.003Eu phosphor was found to be about 41.5%. In addition, the CIE chromaticity coordinates of LiCaZnVO:0.003Eu were ( = 0.3374, = 0.3596), and the correlated color temperature was estimated to be about 5311 K.