Novel multi-wavelength effectively excited ZnWO4-WO3:Eu3+ multiphase red phosphor for white light-emitting diodes

The discovery of phosphor with efficient red emission is a crucial step in the development of the white light-emitting diodes (wLEDs). Herein, based on the regulation of the W/Zn ratio, the Eu³⁺-activated ZnWO₄-WO₃∙0.5H₂O-WO₃ multiphase phosphor was designed successfully via the one-step hydrothermal treatment route. The effects of the W/Zn ratio on the phase structure, composition, morphology, luminescence property and lifetime of the obtained samples were systematically and comparatively investigated. The obtained product not only maintains the multi-wavelength excitation feature of ZnWO₄:Eu³⁺ phosphor, but also sharply improves the characteristic emission intensity of Eu³⁺ ions. It is found that the WO₃∙0.5H₂O crystal has a special 3D interconnected channel structure, which is a relatively much access to the chemical behavior and permits the ready insertion of part of Eu³⁺ ions, and this coordination environment can obtain strong pure red light emission. Further, the ZnWO₄-WO₃:Eu³⁺ phosphor obtained after dehydration treatment can be excited more efficiently in the deep-ultraviolet (DUV), near-ultraviolet (NUV) and blue light regions, and its quantum efficiencies reach 18%, 22% and 21.2%, respectively. Besides, it also exhibits better CIE chromaticity coordinate, higher color purity than commercial Y₂O₂S:Eu³⁺ phosphor. Therefore, the ZnWO₄-WO₃:Eu³⁺ is promising for the application in red phosphor with different wavelengths for wLEDs.