The Study Of Single Matrix With Single/Double/Trible-Color Emitting Luminescent Materials For Plant Growth LED

The nature environment such as temperature and illumination has influence on crops' output and photoperiod.Light not only offers the energy source for plant growth but also controls some of the thousands of processes occurred in plant cell because blue,red and far-red light are generally responsible for photosynthesis,phototropism,and photomorphogenesis,respectively,Near-Infrared light can indirectly promote plant groeth by biological nitrogen fixation.To meet different levels of human needs,the greenhouse industry has been extensively developed in agriculture and horticulture,in which the light environment,including the intensity and spectral composition,was controlled by using different illuminants.The advent of light-emitting diodes?LEDs?provide several unique advantages over existing light systems gas-discharge lamps used in controlled-environment crop production system,such as being power-economical and environmental friendly and having a long lifetime and low radiant heat output.Therefore,LED has the lower energy consumption than traditional light source.This paper choose titanate,niobate,phosphate to be the host because of good physical and chemical stability,then select transition metal ion(Mn⁴⁺,Mn²⁺)and rare earth ion(Eu²⁺,Pr³⁺)as the doping ion,using sol-gel method and high temperature solid state method prepare the blue,red,and near-infrared phosphor which can be used for plant growth LED.The titanate host La?MgTi?_1/2O₃ has good physical and chemical stability with octahedron site which can be occupied by Mn⁴⁺,analysis the lattice symmetry and the density of energy state by ab initio calculation,Mn⁴⁺will occupy the Ti site in the host.The phosphor emitting a red light(Mn⁴⁺:²E_g?⁴A_2g)at 708 nm,the PL spectra of prepared phosphor can well-matched with the absorption spectra of phytochrome P_FR.Through the refinement and first principles calculation,we know the crystal structure of niobate host?Ca,Sr,Ba?₂GdNbO₆ is similar to that of titanate host because they both have octahedron site.The phosphors can emitting the light in red region,the emission position of these three phosphors are different vwhen the alkaline earth metal ion in the host been replaced.,The phosphor Sr₂GdNbO₆:Mn⁴⁺can perfectly well-matched the absorption of chlorophyll a and b in the red light region.Through 4 K low temperature spectra and calculation for crystal site,there are three different high-coordination number sites in the phosphate host Ba₄Gd₃Na₃?PO₄?₆F₂,which can be occupied by doping ion Eu²⁺,thus,multi-color emission can be achieved in a single matrix.Then we choose Eu²⁺as the sensitizer co-doping Mn²⁺or Pr³⁺can achieved blue,red,Near-infrared multi-emitting by energy transfer process,which corresponding to the aborption spectra of bacteriachlorophyll.