Construction And Properties Of Luminescent Materials Based On Ionic Liquids/Deep Eutectic Solvents

Ionic liquids(ILs)are molten salts composed of anions and cations.Deep eutectic solvents(DESs)are mostly deep eutectic mixtures formed by hydrogen bonding between hydrogen bonding receptors and donors.They are widely used in fields such as electrochemistry,catalytic reactions,and gas absorption due to their low volatility,non flammable and explosive properties,high electrical conductivity,and wide electrochemical windows.ILs and DESs have good designability and flexible construction methods.By adjusting the structures of the anions and cations that make up ILs or the hydrogen bond donors and receptors that make up DESs，ILs and DESs with specific functions can be synthesized.By introducing luminescent groups to the anions and cations as luminescent centers,ionic liquid/deep eutectic solvents based luminescent materials can also be obtained.In this paper,we have developed two kinds of luminescent materials,which not only achieved solvent-free synthesis,but also obtained the advantages of both luminescent ability and thermal stability.Ionic liquids are no longer limited to the auxiliary role,and promote the applications in the field of luminescent materials.The paper mainly consists of the following parts:In Chapter 1,the concepts,properties,and applications of ionic liquids(ILs)and deep eutectic solvents(DESs)were summarized,and the luminescent mechanisms of rare earth complexes and organic-inorganic metal halides(OIMHs)luminescent materials were discussed,including the research status,existing problems,and applications of these two luminescent materials.In Chapter 2,EuDESs and TbDESs with red and green light emission were successfully prepared by mixing lanthanide salts with urea.The materials have low viscosity,good thermal stability and solvent quenching resistance.Combined with carbon quantum dots(CDs)obtained by one-step reaction as a blue light source,by controlling the mixing ratios of CDs,EuDESs and TbDESs,a white light fluid with a CIE coordinate of(0.31,0.33)was obtained,showing good white light emission performance.The white light fluid was used to construct a white light LED.Due to the fluid characteristics of EuDESs and TbDESs,the construction method of the white light LED in this work is simple and convenient,avoiding the introduction of solid phosphors,and providing more possibilities for the preparation of large area flexible light emitting devices.In Chapter 3,two 0 D OIMHs luminescent materials,[AVIm]3SbCl6 and[AVIm]3SbBr6,were prepared using an ionic liquid,1-allyl-3-vinyIimidazole halide([AVIM]X),with antimony halide(SbX3).Their structures were determined by single crystal analysis,powder XRD and other tests.The photophysical properties were studied by UV-Visible absorption spectra,time resolved photoluminescence spectra,photoluminescence emission spectra,and excitation spectra.Subsequently,two types of white light phosphors,WL-1 and WL-2,were obtained by mixing[AVIm]3SbCl6 and[AVIm]3SbBr6 with commercial phosphors,thereby obtaining the white light LED devices with high color rendering index.This work enriches the luminescent materials with six coordinated antimony halide polyhedral anions([SbX6]3-)as luminescent centers,for which the halogen ion changes affect the degree of[SbX6]3-distortion and further the luminescent properties,providing useful information for constructing tunable OIMHs luminescent materials based on ionic liquids.