| The current commercial white light is cold white due to the lack of red light component.As an indoor lighting source,cold white light is easy to cause visual fatigue and damages the eyes.Therefore,people pursue warm white light source for indoor lighting.Moreover,most of the preparation methods of luminescent materials are complex,and the reaction materials used are toxic and easy to cause environment pollution in the recent.The participation of reducing agent or reducing atmosphere has increased the production cost and the risk factor in the experiment.And the stability of the obtained materials is not high,which affects the luminous efficiency.This paper focuses on the research of warm white light-emitting materials.Red and green light-emitting materials for LED and single-phase white light-emitting materials excited by ultraviolet light are prepared by low-cost and environment-friendly synthesis methods.The specific work is as follows:(1)Using La(NO3)3,Pr(NO3)3 and NH4F as raw materials,the hollow hexagon LaF3:Pr3+ nanomaterials were prepared by green and non-polluting hydrothermal synthesis.It is found that the nanomaterial excited by blue light with wavelength of 467 nm shows red light of the main emission peaks centered at 612 nm and 721 nm.And it has good thermal stability.The red-emitting nanomaterials are highly compatible with blue LED and can be used to assemble white LED device.(2)Green emission luminescent material of Eu2+-doped 3A zeolite was prepared without reductant and reducing atmosphere through high temperature solid state method,taking Eu2O3 and 3A-zeolite as raw iaterials.And Eu2+-doped 3A zeolite can be excited by UV light with wavelength of 365 nm.Its quantum efficiency is 36.6%.The green LEDs with 231.6 cd/m2 brightness at 3 V working voltage are fabricated.(3)All inorganic pervoskite CsPbBr3 nanocrystals were synthesized by hot injection.Then the polymer(poly(maleic anhydride-alt-1-octadecene),PM AO)coated CsPbBr3 perovskite nanomaterials were obtained via postsynthetic strategy.It is found that the stability is greatly improved when the coating thickness is about 25 nm.After exposure in air for 40 days,the photoluminescence(PL)intensity of the composite remained almost the same.Its PL intensity maintained more than 90%of its initial emission intensity under continuous ultraviolet illumination of 144 h.Upon immersion into water for 24 h,the PL intensity maintained 60%of its initial PL intensity.The stabilities of irradiation,water and oxygen were improved.The warm white LED based on CsPbBr3/PMAO nanomaterial was fabricated,with color coordinate of(0.390,0.332),color temperature of 3320 K,the highest device brightess of 6×106 cd/m2,and high power efficiency of 56.6 lm/W.And the stability of device was improved.(4)Using La(NO3)3,Pr(NO3)3,NH4F and sodium dodecylbenzene sulfonate(SDBS)as raw materials,organic-inorganic hybrid nanomaterials of rare earth based SDBS with elliptical shape were prepared under hydrothermal synthesis.Under the excitation of UV light with wavelength of 365 nm,the emission peak of this material is a wide peak covering the whole visible region(420 nm-750 nm),color coordinates of(0.365,0.412)and color temperature of 4606K.And there are 4 fitting peaks containing the blue emission peaks at 460 nm and 489 nm,the green emission peak at 542 nm and the red emission peak at 619 nm under the Gaussian fitting.The optimum synthesis conditions of organic-inorganic hybrid nanomaterials of rare earth based SDBS were found by orthogonal experiments. |
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