Synthesis And Luminescence Properties Of Manganese(?) And Rare Earth Ions Doped Double Perovskite Materials For Plant Lighting

Light is an important factor for plant growth and fruiting.For the greenhouse industry,solid-state lighting using light-emitting diode(LED)technology represents a completely different and energy-saving method.Compared with the gas discharge lamps(high pressure sodium lamps)currently used in most greenhouses,this method is superior.Therefore,it is very significant to develop new fluorescent materials for plant lighting.In recent years,luminescent materials doped with rare earth(RE)ions and transition metal ions have been widely used in the field of plant lighting due to their unique and superior luminescence properties.In this paper,different RE ions co-doped with Mn⁴⁺were used to synthesize different fluorescent materials for plant lighting,and the thermal stability and electroluminescence properties of the package were studied.The response of different fluorescent materials to ambient temperature changes was studied in detail.A new high thermal stability far-red emission Ca₂Sc Ta O₆:Mn⁴⁺phosphor(CSTO:Mn⁴⁺)has been prepared by high temperature solid-state method.The far-infrared emission peak of the phosphor is located at 692 nm in the wavelength range of 625?750 nm.In addition,the emission spectra of plant CSTO:Mn⁴⁺were well matched with the absorption spectra of photosensitive pigment P_FR.When the doping concentration of Mn⁴⁺ions exceeds 0.4%,the luminescence intensity begins to decrease,and the mechanism of concentration quenching effect is the quadrupole-quadrupole interaction.CSTO:0.4%Mn⁴⁺phosphor has good thermal stability and?E of 0.3686 e V.The relative sensitivity of temperature response of CSTO:0.4%Mn⁴⁺is 3.03%·K^-1(323 K).The packaged LED chip emits strong far-red light,which is similar to CSTO:0.4%Mn⁴⁺phosphor.With the increase of current,the chromaticity shift and color coordinates did not change significantly.CSTO:Mn⁴⁺phosphor has a good application prospect as a far-infrared luminescent material for plant growth light-emitting diodes.La₂ZnTiO₆:Mn⁴⁺/Er³⁺phosphors(LZT:Mn⁴⁺/Er³⁺)were successfully synthesized by sol-gel method.The emission spectra of LZT:Mn⁴⁺/Er³⁺phosphors can be attributed to the emission peaks of Er³⁺:²H_11/2/⁴S_3/2?⁴I_15/2and Mn⁴⁺:²E_g?⁴A_2g,Which consistent with the requirement of plant growth for red and green light.Based on Dexter theory,energy transfer from Er³⁺to Mn⁴⁺ion exists in LZT:Mn⁴⁺/Er³⁺phosphors,and the type of energy transfer is quadrupole-quadrupole interaction.Upon 379 nm excitation,the energy transfer efficiency of LZT:0.2%Mn⁴⁺/2%Er³⁺co-doped sample is 84.7%.At the same time,the response of LZT:Mn⁴⁺/Er³⁺to the change of ambient temperature was studied in detail by using the temperature-dependent fluorescence attenuation curve of Mn⁴⁺.The relative sensitivity of LZT:Mn⁴⁺/Er³⁺to the temperature response was 4.62%·K^-1(298 K).All the results show that a new way for the development of plant growth fluorescent materials with high matching phytochromes P_FR and temperature response to environmental changes.A series of NaLaMgWO₆:Bi³⁺/Mn⁴⁺/Pr³⁺phosphors were successfully synthesized by the sol-gel reaction method.The study found that under the excitation of 451 nm,the doping of Bi³⁺ions can significantly enhance the photoluminescence intensity of Na La Mg WO₆:Mn⁴⁺/Pr³⁺.The emission spectrum of Na La Mg WO₆:Bi³⁺/Mn⁴⁺/Pr³⁺phosphor has two emission peaks at Pr³⁺:³P₀?³H₄/³F₂ and Mn⁴⁺:²E_g?⁴A_2g.These two emission peaks match the absorption spectra of P_R and P_FR,respectively.In the Na La Mg WO₆:Bi³⁺/Mn⁴⁺/Pr³⁺phosphor,the double emission of near red light and far red light is realized,and the R/FR can be adjusted with temperature.In addition,the emission intensity ratio of Mn⁴⁺(675?800 nm)and Pr³⁺(600?675 nm)can be used to measure temperature,where S_a and S_r reach maximum values of2.8%·K^-1 at 298 K and 3.39%·K^-1 at 573 K,respectively.In summary,this research provides a new way for the development of plant growth fluorescent materials with high matching phytochromes(P_R and P_FR)and temperature response to environmental changes.