Search

Abstract: A series of full-color single-phased phosphors for white LEDs (W-LEDs), in the system (Y, Ln)2GeO5 (Ln=Tm, Tb, Eu), were prepared and their photoluminescence properties were characterized. The simultaneous incorporation of Eu3+, Tb3+ and Tm3+ ions in Y2GeO5 lattice can result in an integration of red, green, and blue emissions when being excited by ultraviolet light. Under excitation at 352nm, the color tones of the (Y0.95−x Tm0.01Tb x Eu0.04)2GeO5 phosphors change from cool white to warm white by increasing the concentration of Tb3+, while the intensities of Eu3+ emissions increase. Indeed, in the case of co-doped systems, a very efficient energy that transfers from Tb3+ to Eu3+ occurs. The present phosphors can potentially be used for the high CRI and high luminous efficient white LEDs. [Copyright &y& Elsevier]

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 ZnWO 4 -WO 3 ∙0.5H 2 O-WO 3 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 ZnWO 4 :Eu3+ phosphor, but also sharply improves the characteristic emission intensity of Eu3+ ions. It is found that the WO 3 ∙0.5H 2 O 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 ZnWO 4 -WO 3 :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 Y 2 O 2 S:Eu3+ phosphor. Therefore, the ZnWO 4 -WO 3 :Eu3+ is promising for the application in red phosphor with different wavelengths for wLEDs. • The ZnWO 4 -WO 3 :Eu3+ multiphase phosphor was obtained by tailoring the W/Zn ratio. • The WO 3 ·0.5H 2 O with 3D interconnected channel structure allows the insertion of Eu3+. • The ZnWO 4 -WO 3 :Eu3+ phosphor can be efficiently excited by multi-wavelength bands. • Meritorious CIE, QE and high color purity was obtained. [ABSTRACT FROM AUTHOR]