Research On Manganese Ion-activated Red Phosphor For White LED

The white LED,known as the new generation of light source in the 21st century,has become the core focus of solid-state lighting due to its low voltage,high luminous efficiency,low energy consumption,long life,good stability and environmental friendliness.At present,the development of white LED is limited by its low color rendering index and high color temperature.The performance of red phosphor is pretty important to improve the color rendering index and color temperature of white LED.Nowadays,most of the red phosphors are activated by rare earth ions,and Eu³⁺is a commonly used activator.However,the red phosphors activated by Eu³⁺have weak absorption,which leads to a weak red light and a low luminous efficiency.Most rare earth ions are scarce and expensive.Therefore,if other ions can be used as activators,breakthroughs can be achieved.In this paper,the luminescent properties of various phosphors stimulated by Mn ions were studied.Here are the major details:1)We synthesized the CaAl₁₂O₁₉:Mn⁴⁺phosphors used by the traditional method which is high temperature solid-state to.The effects of Mn⁴⁺source,Mn⁴⁺concentration,charge compensator,sintering temperature and flux content on the luminescent properties of CaAl₁₂O₁₉:Mn⁴⁺phosphors were studied.The results show that the luminescent properties of CaAl₁₂O₁₉:Mn⁴⁺are not affected by either MnCO₃or MnO₂ as the manganese source.When the content of Mn⁴⁺is 1 mol%,the excitation intensity of CaAl₁₂O₁₉:Mn⁴⁺is the highest,so is the emission intensity.The luminescence intensity of CaAl₁₂O₁₉:Mn⁴⁺is the highest when K⁺is used as charge compensator,which is higher than those of Na⁺,Li⁺,Mg²⁺,Ba²⁺,Sr²⁺.When the flux H₃BO₃ content is 5%,CaAl₁₂O₁₉:Mn⁴⁺has the highest luminescence intensity.2)K₃AlF₆:Mn⁴⁺phosphor was synthesized by hydrothermal method.The luminescence properties of different concentrations of Mn⁴⁺and temperatures were studied.The results show that the synthesized K₃AlF₆:Mn⁴⁺phosphors have the highest intensity of main excitation peak and emission peak when the doping concentration of Mn⁴⁺ions is 8 mol%.When the synthesis temperature is 125°C,the luminescence intensity of K₃AlF₆:Mn⁴⁺phosphor reaches a maximum.3)BaNbOF₅:Mn⁴⁺phosphor was synthesized by hydrothermal method,and its luminescence properties at different temperatures and Mn⁴⁺concentrations were studied.It's found that the BaNbOF₅:Mn⁴⁺phosphor has the highest luminescence intensity when the doping concentration of Mn⁴⁺is 6 mol%.When the synthesis temperature is 120°C,the luminescence intensity of BaNbOF₅:Mn⁴⁺phosphor is the largest.4)The Ca₃Al₂?SiO₄?₃:Mn²⁺,Ce³⁺phosphors were also prepared by the traditional high temperature solid-state reaction method.The luminescence properties of different Mn²⁺,Ce³⁺,and Mn²⁺/Ce³⁺co-doped Ca₃Al₂?SiO₄?₃ were studied.From the emission spectrum of Ca₃Al₂?SiO₄?₃:Mn²⁺,Ce³⁺sample,it can be seen that Ca₃Al₂?SiO₄?₃:Mn²⁺,Ce³⁺has a relatively broad band blue emission peak at 431 nm under the excitation of 357 nm light.When the concentration of Ce³⁺is kept constant to be 1 mol%,the emission and excitation intensity of the sample increase first and then decrease with the increase of Mn²⁺ion concentration.When the Mn²⁺ion concentration is 2 mol%,the excitation and emission intensity of the sample is maximized,and the spectral intensity of the sample is much higher than that of the Ca₃Al₂?SiO₄?₃:Ce³⁺sample doped with Ce³⁺alone.It may be inferred that Mn²⁺sensitizes Ce³⁺ions or energy transfer occurs between them.When the concentration of Mn²⁺ions is fixed to be 1%,if the luminescence intensity of Ca₃Al₂?SiO₄?₃:Mn²⁺,Ce³⁺samples will also be increased with the increase of the Ce³⁺concentration.When Ce³⁺ion concentration is 6 mol%,the excitation and emission intensity of the sample get to the highest,and as the Ce³⁺ion concentration continues to increase,the luminescence intensity of the sample decreases,and concentration quenching occurs.