Study On The Synthesis And Enhanced Photoluminescence Properties Of Mn²⁺/Tb³⁺ Doped ?-AlON Narrow-band Green Phosphors

At present,the mainstream white light LED on the market is based on InGaN blue LED chip and Y₃Al₅O₁₂:Ce³⁺yellow phosphor packaged.However,this type of white light LED suffers from defects such as discomfort glare and poor color rendering index which severely limits its application in the field of high-end indoor lighting and wide color gamut backlight display.In order to improve the light color quality of white LEDs,the use of blue light chip and green-red phosphors or near-UV chip and red-green-blue?RGB?phosphors packages has become two effective strategies that are expected to eliminate these disadvantages.Traditional green phosphors that can be applied currently have problems such as high thermal quenching,low luminescence efficiency and wide band,and it is difficult to meet the demand for high-quality white LEDs.Therefore,the study of high-efficiency narrow-band green phosphors is imminent.Mn²⁺and Tb³⁺are common activators of green phosphor,but both suffer from the disadvantage of low luminescence efficiency.For this purpose,this subject uses?-AlON as the matrix,Mn²⁺or Tb³⁺as effective light emitting centers and uses energy transfer or charge compensation strategies to achieve efficient narrow-band green emission of Mn²⁺and Tb³⁺to meet high-quality white LED device applications.The main research contents and results are as follows:?1?The luminescence behavior of Eu²⁺-Mn²⁺and Eu²⁺-Tb³⁺doped?-AlON systems was studied and compared,and the factors affecting energy transfer efficiency and thermal stability were analyzed.The study found that the excitation spectrum of single-doped?-AlON:Eu²⁺have strong absorption in the near ultraviolet region,which can match the near ultraviolet LED chip.The Gaussian peaks of the asymmetric emission of Eu²⁺indicate that Eu²⁺occupies two Al³⁺lattice sites.Under near ultraviolet excitation,by controlling the doping concentration of Eu²⁺and Mn²⁺/Tb³⁺,the emission color can be adjusted between blue and green.Among them,the Eu²⁺-Mn²⁺co-doping system exhibits dual emission bands of Eu²⁺?⁴00 nm?and Mn²⁺?⁵10nm,full-width at half-maximum about 30 nm?.In Eu²⁺-Tb³⁺system,Tb³⁺exhibits green emission with a main peak around 540 nm?full-width at half-maximum about 10 nm?.With the increase of Mn²⁺or Tb³⁺doping concentration,the emission band of Eu²⁺obviously weakened or almost disappeared,while the green emission of Mn²⁺and Tb³⁺increased by about 15 times and 20 times,respectively,and the attenuation of Eu²⁺fluorescence lifetime further proved the occurrence of efficient energy transfer.The highest energy transfer efficiencies of Eu²⁺-Mn²⁺and Eu²⁺-Tb³⁺systems are 28%and 80%,respectively.Through the comparison and analysis of the energy transfer efficiency and spectral overlap position of the two systems,it is believed that a good overlap between the emission of the sensitizer and the lowest excitation energy level of the activator may be an important factor for achieving higher energy transfer efficiency.The optimal samples?-AlON:0.003Eu²⁺,0.10Mn²⁺and?-AlON:0.003Eu²⁺,0.01Tb³⁺at 150?,the relative emission intensity is maintained at about 82%and 51%at room temperature,showing good thermal quenching performance.The relatively poor thermal stability of the latter is due to the lattice distortion caused by the large radius difference between Eu²⁺and Tb³⁺and Al³⁺,which leads to the destruction of the original rigid structure of the lattice.?2?The effects of a series of different charge compensator ions on the luminescence properties and surface morphology of?-AlON:Mn²⁺,Mg²⁺phosphors were studied,two mechanisms of enhanced luminescence were proposed,the effect of different charge compensators on the thermal stability of the sample was analyzed,and the color purity was calculated.The study found that after the introduction of the charge compensator,the surface of the sample particles was smooth and better dispersed,and the integrated emission intensity was significantly improved:Li⁺?1.92 times?,Na⁺?1.89 times?,K⁺?1.78 times?,and Si⁴⁺?2.36times?.This is because the introduction of charge compensator ions can effectively reduce crystal defects,lattice stress and reduce the probability of non-radiative transitions.Secondly,the integrated emission intensity of Li⁺and Si⁴⁺doped samples at 150?enhanced from 85%to 93%and 90%of the original sample,due to the close radius of Al³⁺and the destruction of the original rigid structure of the lattice..In addition,the green color purity of the samples added with Li⁺,Na⁺,K⁺,and Si⁴⁺has been improved,and the sample with K⁺ion added has an excellent color purity of 93.86%.