Preparation Of Light-converting Material Based On Rare Earth Organic Complex And Their Fluorescence Research

With the development of society and the increasing population,there is a huge demand for energy and efficient food production.Solar energy is the most abundant renewable energy available to us.How to use solar energy efficiently has become the focus of current research.Crops typically use only a small portion of the solar spectrum,the blue(400-500 nm)and red(600-700 nm)light waves absorbed by chlorophyll pigments,while most of the other wavelengths are wasted.Therefore,it is necessary to develop a material to improve the utilization efficiency of sunlight.This material absorbs sunlight that is not used by plants and converts it into blue or red light.At present,there is a part of functional agricultural film doped with light-converting material on the market.This kind of agricultural film can improve the utilization rate of light energy of crops by converting unused purple light,ultraviolet light and yellow-green light in solar energy,and achieve the purpose of increasing crop yield.Such a light-converting material mainly comprises inorganic light-converting material,which can exhibit different colors and light absorption conditions,organic dye-based light-converting material and organic complex-based light-converting material,which have good compatibility with polymer film,and MOF-based light-converting material with good monochromaticity.However,in the actual use process,the light-converting material may have problems such as weak luminous intensity,poor compatibility with the polymer film,and poor stability during use.Therefore,it is imperative to develop a light-converting materials which have high fluorescence intensity,better stability and compatibility with polymer materials,and low price.In this paper,we combined the advantages of organic complexes,inorganic fluorescent materials,MOFs and organic dyes to develop several kinds of red light-emitting materials.And we also studied the influence of some conditions on the fluorescence.The details are as follows:(1)We use multi-step reaction to prepare 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin containing carboxyl group.And we prepared the red light-emitting complex with porphyrin as organic ligand chain and RhB by one-pot method.The incorporation of RhB into the complex enhances the red fluorescence emission intensity of the organic complex about 1 time.The structure and properties of the materials were studied by FT-IR,XRD,SEM,UV absorption spectroscopy and fluorescence spectroscopy.It was found that the prepared doped organic ligands have better red light emission properties,and their emission peaks are around 660 and 750 nm while maintaining good red emission in daylight.(2)A light-converting material combining double rare earth metal complex and LDH was prepared by ball milling.The light-converting materials were characterized by FT-IR,XRD,SEM,TGA and fluorescence spectroscopy.The experimental characterization proves that the prepared double rare earth metal-organic complex is intercalated into the hydrotalcite-like layer,which makes the hydrotalcite-like composite material have the fluorescence emission performance located at 615 and 725 nm.The interaction of the organic ligand with the metal ions in the laminate by the intercalation increases the fluorescence intensity to 0.6 times.Hydrotalcite-like compounds offer the possibility of industrial scale production of lightconverting materials due to their mature preparation process.(3)A light-converting material of a fluorescence-enhanced multi-ligand is prepared by linking two complexes together by modification of an amino group.The composite lightconverting material was characterized by means of FT-IR,SEM,XPS,XRD and fluorescence spectroscopy.The experimental structure indicates that the modification of the amino group is successful,and due to the sensitization of different ligands,the characteristic emission peak of the rare earth europium ion is further enhanced,and the fluorescence emission intensity of the final composite material is also enhanced,avoiding the light competition.(4)Two kinds of red light-emitting materials were prepared by hydrothermal method with europium as the metal center and terephthalic acid and 1,3,5-benzenetricarboxylic acid as organic ligand chains.Various characterizations were used to confirm if the metal ions and organic chains were coordinated.At the same time,it was found that the optimal hydrothermal synthesis temperature and time for the terephthalic acid-based MOF were 110 °C and 48 h,while the optimal synthesis temperature and time for the 1,3,5-benzenetricarboxylic acid-based MOF were 120 °C and 48 h.Due to the energy transfer between the ligand and the metal ruthenium,the prepared MOF material exhibits a red light characteristic emission of ruthenium.(5)Sulfide nanomaterials with red light emission were prepared by high temperature solid phase synthesis,and the organic-inorganic composite light-converting materials were prepared by doping the sulfide into MOF by one-pot method.The prepared samples were characterized by FT-IR,XRD,SEM,fluorescence spectroscopy,TGA,etc.The experimental results show that the sulfide and MOF materials have good red fluorescence emission,and the fluorescence intensity of the composite is improved about 0.5 times by the energy resonance transfer between the sulfide and the MOF material,and the thermal properties of the composite are increased.