The Synthesis And Properties Of Color-Tunable And White-Light Emitting Based On Single Matrix Lanthanide-Polyoxometalate Compounds

White-light-emitting materials have broad applications in the flat panel display, backlight and illumination. The poor match of phosphor was main problem for white LED, and the low excitation efficiency for the main emission band about near ultraviolet chip. It is difficult for compatibility and mixing among different phosphor systems. The color reabsorption problem affects the luminous efficiency. Single matrix phosphor have attracted considerable attention because of their homogeneous phase and stable property. Currently, there are still some problems about single matrix luminescence materials, which exhibiting emission components missing or inadequate and low CRI. For LED chips, multilayer films still have some drawbacks, such as each layer in the multilayer film needing its voltages and each layer having different aging rate and chemical stability. However, monolayer film prepared by physical mixing method also have problems, which may not give rise to uniformly dispersion, thermodynamically stable compositions and color reabsorption. To overcome the problems for blending different colors of light-emitting compounds and light color reabsorption, we seek a polyoxometalate as matrix material for fluorescence emitting materials, higher emission intensity and single matrix fluorescent material, then synthesis single matix single layer film to obtained full spectrum color (red, green, blue, white) film. The paper includes as following:(1) A series of compounds of lanthanide metal-organic framework based on Anderson-type polyanion, which as basic inorganic building bock were synthesized by a simple inorganic salt AlCl3, Na2MoO4, nicotinic acid as raw material and lanthanide nitrates,[Na(HL)(CH3COO)Ln(AlMo6(OH)6O18)(H2O)6]2·20H2O (HL:nicotinic acid, Ln:Eu (1), Tb(2)),[Na(HL)(CH3COO)EumTbmLa1-w-n(AlMo6(OH)6O18)(H2O)6]220H2O(L nicotinic acid)(3-7). The compounds were characterized by UV-vis spectra, IR spectra, elemental analysis, powder XRD method and TG-DTA. The single crystal structure of compound2was obtained by single crystal x-ray diffraction analysis. The fluorescence properties of compounds1,2and light emitting colour of series compounds were studied. The compounds exhibit tunable luminescence color and white light emitting by only adjusting the molar ratio of Eu:Tb:La. The energy transfer mechanism of lanthanide-organic framework materials based on Anderson-type polyanion were studied. (2) The POMs of Na9LnW10O36was used as a new luminescent substrate, compound emission color can be modulated by change Eu3+, Tb3+, Ce3+ratio and white light emission material finally obtained. A series of ultra-thin single matrix single layer light-emitting films based on polyoxometalates Na9EumTbnCe1-m-nW10O36were prepared by a simple and effective spin-coating method. The films exhibit luminescence color tunable over a wide range (blue, green, red and white) by only adjusting the molar ratio of Ce3+:Tb3+:Eu3+in Na9Eu,nTbnCei.m.nWio036. White light emission film was obtained in a molar ratio of Ce3+:Tb3+: Eu3+being3.0:1.0:0.05, namely Na9Eu0.0123Tb0.246Ce0.741W10O36. The films were characterized by IR spectra, powder X-ray diffraction (XRD), ICP, UV, scanning electron microscope (SEM). The results obtained in this work provide definitely new opportunities in designing the optical functional materials based on polyoxometalates.