The development of novel near-infrared(NIR)phosphors that simultaneously satisfy diverse performance needs is extremely difficult in the vast materials space.In this paper,we propose a novel approach combining three-o...The development of novel near-infrared(NIR)phosphors that simultaneously satisfy diverse performance needs is extremely difficult in the vast materials space.In this paper,we propose a novel approach combining three-objective optimization(TOO)and crystal field engineering(CFE)for the development of new NIR phosphors.Utilizing the efficient optimization capabilities of machine learning in a high-dimensional space and the extended advantages of CFE in specific material systems,we successfully discovered a new NIR phosphor,LaGa_(0.5)Sb_(1.5)O_(6):Cr^(3+),with an excellent performance,which emerged from the LnAmB_(2-m)O_(6):Cr^(3+)(Ln=La,Gd;A=Al,Ga,In,Mg;B=Sb,Te;m=0.5,1/3)family.LaGa_(0.5)Sb_(1.5)O_(6):Cr^(3+)exhibited a broadband emission in the range 700–1200 nm(λmax=850 nm)with a full width at the half maximum(FWHM)of 200 nm and an internal quantum efficiency(IQE)of 55.4%.Moreover,65% of its initial emission intensity could be maintained when heated to 393 K.This study paves a promising way for the rapid development of novel NIR phosphors with multiple essential properties.展开更多
Controlled energy transfer has been found to be one of the most effective ways of designing tunable and white photoluminescent phosphors.Utilizing host emission to achieve the same would lead to a new dimension in the...Controlled energy transfer has been found to be one of the most effective ways of designing tunable and white photoluminescent phosphors.Utilizing host emission to achieve the same would lead to a new dimension in the design strategy for novel luminescent materials in solid state lighting and display devices.In this work,we have achieved controlled energy transfer by suppressing the host to dopant energy transfer in La_(2)Hf_(2)O_(7):Eu^(3+)nanoparticles(NPs)by co-doping with uranium ions.Uranium acts as a barrier between the oxygen vacancies of the La_(2)Hf_(2)O_(7) host and Eu^(3+)doping ions to increase their separation and reduce the non-radiative energy transfer between them.Density functional theory(DFT)calculations of defect formation energy showed that the Eu^(3+)dopant occupies the La^(3+)site and the uranium ion occupies the Hf^(4+)site.Co-doping the La_(2)Hf_(2)O_(7):Eu^(3+)NPs with uranium ions creates negatively charged lanthanum and hafnium vacancies making the system highly electron rich.Formation of cation vacancies is expected to compensate the excess charge in the U and Eu co-doped La_(2)Hf_(2)O_(7) NPs suppressing the formation of oxygen vacancies.This work shows how one can utilize the full color gamut in the La_(2)Hf_(2)O_(7):Eu^(3+),U6+NPs with blue,green and red emissions from the host,uranium and europium,respectively,to produce near perfect white light emission.展开更多
基金financially supported by the National Key Research and Development Program of China(2021YFB3501502)Guangdong Province Key Area R&D Program(2019B010940001)+1 种基金National Natural Science Foundation of China(52201061,U22A20106)Fundamental Research Funds for the Central Universities(FRF-TP-22-008A1).
文摘The development of novel near-infrared(NIR)phosphors that simultaneously satisfy diverse performance needs is extremely difficult in the vast materials space.In this paper,we propose a novel approach combining three-objective optimization(TOO)and crystal field engineering(CFE)for the development of new NIR phosphors.Utilizing the efficient optimization capabilities of machine learning in a high-dimensional space and the extended advantages of CFE in specific material systems,we successfully discovered a new NIR phosphor,LaGa_(0.5)Sb_(1.5)O_(6):Cr^(3+),with an excellent performance,which emerged from the LnAmB_(2-m)O_(6):Cr^(3+)(Ln=La,Gd;A=Al,Ga,In,Mg;B=Sb,Te;m=0.5,1/3)family.LaGa_(0.5)Sb_(1.5)O_(6):Cr^(3+)exhibited a broadband emission in the range 700–1200 nm(λmax=850 nm)with a full width at the half maximum(FWHM)of 200 nm and an internal quantum efficiency(IQE)of 55.4%.Moreover,65% of its initial emission intensity could be maintained when heated to 393 K.This study paves a promising way for the rapid development of novel NIR phosphors with multiple essential properties.
基金support from the National Science Foundation under CHE(award#1952803 and#1710160)the United States-India Education Foundation(USIEF)and the Institute of International Education(IIE)for his Fulbright Nehru Postdoctoral Fellowship(award#2268/FNPDR/2017).
文摘Controlled energy transfer has been found to be one of the most effective ways of designing tunable and white photoluminescent phosphors.Utilizing host emission to achieve the same would lead to a new dimension in the design strategy for novel luminescent materials in solid state lighting and display devices.In this work,we have achieved controlled energy transfer by suppressing the host to dopant energy transfer in La_(2)Hf_(2)O_(7):Eu^(3+)nanoparticles(NPs)by co-doping with uranium ions.Uranium acts as a barrier between the oxygen vacancies of the La_(2)Hf_(2)O_(7) host and Eu^(3+)doping ions to increase their separation and reduce the non-radiative energy transfer between them.Density functional theory(DFT)calculations of defect formation energy showed that the Eu^(3+)dopant occupies the La^(3+)site and the uranium ion occupies the Hf^(4+)site.Co-doping the La_(2)Hf_(2)O_(7):Eu^(3+)NPs with uranium ions creates negatively charged lanthanum and hafnium vacancies making the system highly electron rich.Formation of cation vacancies is expected to compensate the excess charge in the U and Eu co-doped La_(2)Hf_(2)O_(7) NPs suppressing the formation of oxygen vacancies.This work shows how one can utilize the full color gamut in the La_(2)Hf_(2)O_(7):Eu^(3+),U6+NPs with blue,green and red emissions from the host,uranium and europium,respectively,to produce near perfect white light emission.
