Preparation And Photoluminescence Properties Of Oxide Based W-LED Used Materials Under Near-ultraviolet Or Blue Light Excitation

White light-emitting diode?referred to as w-LED?solid-state light source as the latest generation of lighting devices,with its revolutionary nature of the excellent has received more and more attention.Common white LED production methods are the three primary color chip combination method and chip plus phosphor combination?fluorescence conversion method,referred to as pc-LED?.Among them,phosphor material is an indispensable key factor for producing white light.The blue chip plus yellow phosphor method as the representative in pc-LED is one of the most widely used way currently on the market;in order to solve the blue chip plus yellow phosphor of birth defects,another type of pc-LED production that is near-ultraviolet chip plus trichromatic phosphors have also been widely studied.In this thesis,some problems existing in the two production modes of pc-LED are investigated systematically by means of material structure design,structure refinement,synthesis condition control,theoretical simulation and luminescence property characterization.Several near-UV and blue-light excited oxidation luminous materials,its main research are as follows:1.Aiming at the problems of near-ultraviolet excited blue and green phosphors,three kinds of luminescent materials with short wavelength emission in visible light range were synthesized by high temperature solid-state method.K₂ZrSi₃O₉ and Eu²⁺activated K₂ZrSi₃O₉ have been studied to explore the new materials for phosphor-converted white light near ultraviolet light-emitting diodes?NUV-LEDs?.The CIE chromaticity coordinates and FWHM of the blue phosphor K₂ZrSi₃O₉:1%Eu²⁺are?0.1538,0.1857?and 57 nm.The photoluminescence properties of co-doped Eu²⁺-Al³⁺and Eu²⁺-Sc³⁺charge compensation pairs phosphors were investigated.The Eu²⁺single-doped K₂ZrSi₃O₉ phosphor shows blue emission with the broad-band peaking at 465nm upon 400 nm NUV excitation.By Eu²⁺-Al³⁺as charge compensation,the photoluminescence properties do not change distinctly,while the photoluminescence emission spectrum shifts to red area about 39 nm and becomes green emission by using Eu²⁺-Sc³⁺pair.Different occupying situations with different charge compensation pairs were discussed.Blue and green emission can be yielded in K₂ZrSi₃O₉:Eu²⁺compound by different charge compensation mechanism.It reveals that K₂ZrSi₃O₉:Eu²⁺possesses remarkable optical properties and can be used in NUV-LEDs.A novel apatite mineral of Ba₅?PO₄?₂SiO₄ was synthesized successfully.Ba₅?PO₄?₂SiO₄ was found to be hexagonal crystal system and the space group is attributed to P 63/m?176?.Ba₅?PO₄?₂SiO₄:Eu²⁺can emit green light peaking at⁵15 nm under 405 nm NUV excitation with quantum efficiency31.89%.According to structure and photoluminescence?PL?properties analysis,Eu²⁺can occupy two kinds of Ba²⁺site.It has not good temperature stability properties because of too much temperature-dependent electron–phonon interaction at high temperature.The fabricated white-LEDs using a 405 nm GaN NUV chip combined with a blend of RGB phosphors:CaAlSiN₃:Eu²⁺,Ba₅?PO₄?₂SiO₄:1%Eu²⁺and BAM:Eu²⁺,driven by 30 mA current can get warm-white light with chromaticity coordinates?0.355,0.342?and correlated color temperature?CCT?4561 K.A new garnet compound Ca₃Hf₂SiAl₂O₁₂ and a series of Ce³⁺-doped phosphor Ca₃Hf₂SiAl₂O₁₂:xCe³⁺were synthesized.Ca₃Hf₂SiAl₂O₁₂2 belongs to body-centered cubic and Ia-3d?230?space-group with a=12.3666?.Ca₃Hf₂SiAl₂O₁₂:xCe³⁺took on broad excitation bands at 330 and 400 nm attributed to Ce³⁺characteristic 5d-4f transition and can emit cyan emission under 400 nm UV light excitation.The emission intensity of CHSA:1%Ce³⁺phosphor can reach to 68.9%of YAG:Ce³⁺?commercial?and 72.1%of Ca₈Mg?SiO₄?₄Cl₂:Eu²⁺?commercial?.In the process of increasing the temperature from 25°C to 250°C,the integrated emission intensity of Ca₃Hf₂SiAl₂O₁₂:0.5%Ce³⁺is only decreased to 57.8%?250°C?and shows nice thermal stability comparing with commercial YAG:Ce³⁺?P46-Y3?.Furthermore,Ca₃Hf₂SiAl₂O₁₂:0.5%Ce³⁺exhibits outstanding quantum efficiency?74.7%?.2.In order to solve the problem of near-ultraviolet excited red-orange light-emitting materials,two kinds of long-wavelength emission phosphors were developed.Sr₉?Li,Na,K?Mg?PO₄?₇ was found to be trigonal,belonging to R-3m?166?space group.As a representative,the PL properties of Sr₉LiMg?PO₄?₇:Eu²⁺are investigated detail.It can emit orange light peaking at 635 nm with405 nm excitation.According to structure and photoluminescence?PL?properties analysis,Eu²⁺can occupy three kinds of Sr²⁺site.By tuning weight ratio of blue and orange phosphors,the fabricated white-LEDs using a 405 nm GaN NUV chip combined with a blend of blue phosphor BAM:Eu²⁺and orange emitting Sr₉LiMg?PO₄?₇:0.04Eu²⁺phosphor driven by 30 mA current can get tunable white light with chromaticity coordinates from?0.3535,0.3011?and CCT 4287 K to?0.4036,0.3539?and 3131 K.LiBa₁₂?BO₃?₇F₄:Eu²⁺can emit red light peaking at⁶44 nm under NUV excitation with the coordinate at?0.6350,0.3586?and a sensitive color gamut for eyes.This phosphor with a kind of special tunnel crystal structure and layered distribution of Ba²⁺is contributed to longer wavelength emission.By theoretical calculation and analysis using local state density energy band structure simulation of Eu²⁺doped in different site,the origin of the observed emission center is distinguished.Temperature dependent PL spectra appeared anomalous phenomena that the intensity increases firstly and then decreases,which is due to the traps energy level's contribution of electron's transition.The phosphor also has cathodoluminescence?CL?property which the spectra take on typical current saturation phenomenon.And the CL curves indicated that this phosphor has a very good stability under much electron beam bombardment time.After fabricated,combing with BAM,?Sr,Ba?₂SiO₄ and our red phosphor excited under 405nm NUV chips,warm light LED was gotten,and,its CIE coordinate is?0.3475,0.3416?and the CCT,Ra and luminous efficiency is 4856 K,84.1 and 72.6 lm/W.3.Aiming at the problem of blue-excited red phosphor,two kinds of red luminescent materials doped with Mn⁴⁺have been developed.A series of novel red emission Mg₃Ga₂GeO₈:Mn⁴⁺phosphors under NUV and blue excitation are synthesized successfully by traditional high temperature solid-state reaction.It has one octahedral site and tetrahedral site in crystal structure.According to XRD and photoluminescence?PL?properties analysis,Mn⁴⁺can occupy octahedral(Mg²⁺/Ga³⁺)site.T It can emit red light peaking at 659 nm under NUV excitation.The CIE chromaticity coordinates and FWHM are?0.295,0.677?and 24 nm.It demonstrated that MGG:Mn⁴⁺has high color purity.The PL intensity of MGG:0.5%Mn⁴⁺drops to 72%when the temperature is raised up to 150 ^oC.By tuning weight ratio of blue,green and red phosphor,the fabricated white-LEDs using a 405 nm GaN NUV chip combined with a blend of blue phosphor BAM:Eu²⁺,green phosphor Sr₂SiO₄:Eu²⁺and red emitting MGG:Mn⁴⁺phosphor driven by 40mA current can get white light with chromaticity coordinates?0.316,0.375?and CCT 3340 K.K₂Ge₄O₉ can emit red light peaking at 663 nm under UV or blue light excitation.The CIE chromaticity coordinates and FWHM are?0.702,0.296?and 20 nm which demonstrated that K₂Ge₄O₉:Mn⁴⁺has high color purity.By tuning weight ratio of yellow and red phosphor,the fabricated white-LEDs using a 455 nm InGaN blue chip combined with a blend of yellow phosphor YAG:Ce³⁺and red emitting KGO:Mn⁴⁺phosphor driven by 40 mA current can get white light with chromaticity coordinates?0.405,0.356?and CCT 3119 K.It indicated that K₂Ge₄O₉:Mn⁴⁺is a potential red phosphor matching with blue LED chips to get warm white light.