Trivalent lanthanide(Ln2+)doped luminescent nanocrystals are promising for applications ranging from biosensor,lasing,super-resolution nanoscopy,information security and so on.Although the utility prospect is of great...Trivalent lanthanide(Ln2+)doped luminescent nanocrystals are promising for applications ranging from biosensor,lasing,super-resolution nanoscopy,information security and so on.Although the utility prospect is of great attractions,the light absorption of these lanthanide doped nanocrystals is inherently weak due to the electric dipole-forbidden 4f→4f transitions.Even worse,the quantum yields of upconverison nanocrystals are very low,which will unavoidably hinder their further applications.In a typical lanthanide luminescent nanosystem,both sensitizers as light absorption centers and activators as light emitting centers are necessary and important for desired luminescence properties.Among various sensitization systems,only Yb3+and Nd+are considered as the most efficient sensitizers.Thus,the corresponding excitation wavelengths are strictly limited around 980 and 808 nm.To enrich excitation wavelengths and boost luminescence intensity,exploring more sensitization units that possess larger absorption cross section,higher efficiency of energy transfer process and independent excitation is imperative and beneficial for the demands of different applications,such as broadened absorption in near infrared(NIR)region for higher conversion efficiency of solar cells,prolonged excitation wavelength to second near infrared windows region(NIR Ⅱ,1,000-1,700 nm)for in vivo fluorescence imaging with deeper tissue depth and higher spatial resolution,more orthogonal excitations and emissions to improve optical multiplexing,and so on.Therefore,in the review,we primarily conclude several major energy transfer mechanisms from sensitizers to activators.Then we present three kinds of sensitizers,including lanthanide ions,organic dyes and quantum dots(QDs),and introduce the newly designed sensitization system that allows us to exploit superior excitation wavelength and amplity luminescence intensity.Finally,several future challenges and opportunities for the sensitizing strategies are discussed in hope of directing and broadening the a展开更多
We report herein a class of superatomic AU13 clusters stabilized by different N-heterocyclic carbenes(NHCs).The clusters show diverse metal surface structures,properties and functions as exemplified by:(1)the first an...We report herein a class of superatomic AU13 clusters stabilized by different N-heterocyclic carbenes(NHCs).The clusters show diverse metal surface structures,properties and functions as exemplified by:(1)the first anionic AU13 cluster[Au1g(NHC-1)sBr6],which has bulky NHC-1 ligands that lead to a rather open metal surface contributing to its high catalytic activity;(2)the tricationic cluster[Au13(NHC-2)sBr2]+which has bidentate,benzyl-rich NHC-2 ligands that make it ultra-stable and highly-luminescent,suitable for bio-imaging;and(3)by bearing two pyridyl groups on NHC-3,the dicationic cluster[Au:a(NHC-3)gClg]f+exhibits reversible and stable visible absorption and solubility responses to protonation/deprotonation cycles,making it a potential pH sensor(NHC-1=1,3-disopropylbenzimidazolin-ylidene;NHC-2=1,3-bis(1-benzyl-1H-benzimidazol-1-ium-yl)propane;NHC-3=1,3-bis(icolyI)benzimidazolin-ylidene).The study nicely demonstrates the importance of ligands in designing metal nanoclusters with desired functionalities.展开更多
Exploiting the synergy between microstructure, morphology and dimensions by suitable nanomaterial engineeri ng, can effectively upgrade the physical properties and material performances. Li2SnO3 elongated nano- and mi...Exploiting the synergy between microstructure, morphology and dimensions by suitable nanomaterial engineeri ng, can effectively upgrade the physical properties and material performances. Li2SnO3 elongated nano- and microstructures in form of belts, wires, rods and branched structures have been fabricated by a vapor-solid method at temperatures ranging from 700 to 900℃ using metallic Sn and Li2CO3 as precursors. The achievement of these new morphologies can face challenging applications for Li2SnO3, not only in the field of energy storage, but also as building blocks in optoelectronic devices. The micro? and nanostructures grown at 700 and 800℃ correspond to monoclinic Li2SnO3, while at 900℃ complex Li2S nO/SnO2 core-shell microstructures are grow n, as con firmed by X-ray diffractio n and Rama n spectroscopy. Transmission electron microscopy reveals structural disorder related to stacking faults in some of the branched structures, which is associated with the prese nee of the low-temperature phase of L12S nO3. The luminescent resp onse of these structures is domi nated by in tense emissi ons at 2, 2.5 and 3 eV, almost completely covering the whole range of the visible light spectrum. As a result, white-light emission is obtained without the need of phosphors or complex quantum well heterostructures. Enhanced functionality in applications such as in light-emitting devices could be exploited based on the high luminescenee intensity observed in some of the analysed Li2SnO3 structures.展开更多
An efficient and convenient one-step process was developed for synthesizing new effective red luminous materials through ordered mesoporous γ-alumina assembling with Eu3＋. Employing P123 as a structure-directing age...An efficient and convenient one-step process was developed for synthesizing new effective red luminous materials through ordered mesoporous γ-alumina assembling with Eu3＋. Employing P123 as a structure-directing agent and hydrochloric acid, citric acid as pH adjustor, ordered mesoporous γ-alumina was fabricated by simple sol-gel method. The pore structure was characterized by X-ray diffraction （XRD）, N2 adsorption-desorption isotherms and transmission electron microscopy （TEM）. The as-synthesized γ-aluminas had narrow pore-size distribution （5–7 nm）, large surface area （246 m2/g） and high thermal stability （750–1000 oC）. The luminous property of materials was characterized by Photoluminescence （PL） spectra. The γ-Al2O3：Eu3＋ materials had efficient luminescence, and the emission strength was related to the content of Eu3＋.展开更多
基金the National Key R&D program of China(No.2017YFA0207303)the National Natural Science Foundation of China(Nos.21725502 and 21701027)Key Basic Research Program of Science and Technology Commission of Shanghai Municipality(No.17JC1400100).
文摘Trivalent lanthanide(Ln2+)doped luminescent nanocrystals are promising for applications ranging from biosensor,lasing,super-resolution nanoscopy,information security and so on.Although the utility prospect is of great attractions,the light absorption of these lanthanide doped nanocrystals is inherently weak due to the electric dipole-forbidden 4f→4f transitions.Even worse,the quantum yields of upconverison nanocrystals are very low,which will unavoidably hinder their further applications.In a typical lanthanide luminescent nanosystem,both sensitizers as light absorption centers and activators as light emitting centers are necessary and important for desired luminescence properties.Among various sensitization systems,only Yb3+and Nd+are considered as the most efficient sensitizers.Thus,the corresponding excitation wavelengths are strictly limited around 980 and 808 nm.To enrich excitation wavelengths and boost luminescence intensity,exploring more sensitization units that possess larger absorption cross section,higher efficiency of energy transfer process and independent excitation is imperative and beneficial for the demands of different applications,such as broadened absorption in near infrared(NIR)region for higher conversion efficiency of solar cells,prolonged excitation wavelength to second near infrared windows region(NIR Ⅱ,1,000-1,700 nm)for in vivo fluorescence imaging with deeper tissue depth and higher spatial resolution,more orthogonal excitations and emissions to improve optical multiplexing,and so on.Therefore,in the review,we primarily conclude several major energy transfer mechanisms from sensitizers to activators.Then we present three kinds of sensitizers,including lanthanide ions,organic dyes and quantum dots(QDs),and introduce the newly designed sensitization system that allows us to exploit superior excitation wavelength and amplity luminescence intensity.Finally,several future challenges and opportunities for the sensitizing strategies are discussed in hope of directing and broadening the a
基金the National Key R&D Program of China(No.2017YFA0207304)the National Nautural Science Foundation of China(Nos.21890752,21731005,21802109,and 21721001)the fundamental research funds for central universities(No.20720190043)for financial support.
文摘We report herein a class of superatomic AU13 clusters stabilized by different N-heterocyclic carbenes(NHCs).The clusters show diverse metal surface structures,properties and functions as exemplified by:(1)the first anionic AU13 cluster[Au1g(NHC-1)sBr6],which has bulky NHC-1 ligands that lead to a rather open metal surface contributing to its high catalytic activity;(2)the tricationic cluster[Au13(NHC-2)sBr2]+which has bidentate,benzyl-rich NHC-2 ligands that make it ultra-stable and highly-luminescent,suitable for bio-imaging;and(3)by bearing two pyridyl groups on NHC-3,the dicationic cluster[Au:a(NHC-3)gClg]f+exhibits reversible and stable visible absorption and solubility responses to protonation/deprotonation cycles,making it a potential pH sensor(NHC-1=1,3-disopropylbenzimidazolin-ylidene;NHC-2=1,3-bis(1-benzyl-1H-benzimidazol-1-ium-yl)propane;NHC-3=1,3-bis(icolyI)benzimidazolin-ylidene).The study nicely demonstrates the importance of ligands in designing metal nanoclusters with desired functionalities.
文摘Exploiting the synergy between microstructure, morphology and dimensions by suitable nanomaterial engineeri ng, can effectively upgrade the physical properties and material performances. Li2SnO3 elongated nano- and microstructures in form of belts, wires, rods and branched structures have been fabricated by a vapor-solid method at temperatures ranging from 700 to 900℃ using metallic Sn and Li2CO3 as precursors. The achievement of these new morphologies can face challenging applications for Li2SnO3, not only in the field of energy storage, but also as building blocks in optoelectronic devices. The micro? and nanostructures grown at 700 and 800℃ correspond to monoclinic Li2SnO3, while at 900℃ complex Li2S nO/SnO2 core-shell microstructures are grow n, as con firmed by X-ray diffractio n and Rama n spectroscopy. Transmission electron microscopy reveals structural disorder related to stacking faults in some of the branched structures, which is associated with the prese nee of the low-temperature phase of L12S nO3. The luminescent resp onse of these structures is domi nated by in tense emissi ons at 2, 2.5 and 3 eV, almost completely covering the whole range of the visible light spectrum. As a result, white-light emission is obtained without the need of phosphors or complex quantum well heterostructures. Enhanced functionality in applications such as in light-emitting devices could be exploited based on the high luminescenee intensity observed in some of the analysed Li2SnO3 structures.
基金Project supported by the National Natural Science Foundation of China (21071063, 50872045)
文摘An efficient and convenient one-step process was developed for synthesizing new effective red luminous materials through ordered mesoporous γ-alumina assembling with Eu3＋. Employing P123 as a structure-directing agent and hydrochloric acid, citric acid as pH adjustor, ordered mesoporous γ-alumina was fabricated by simple sol-gel method. The pore structure was characterized by X-ray diffraction （XRD）, N2 adsorption-desorption isotherms and transmission electron microscopy （TEM）. The as-synthesized γ-aluminas had narrow pore-size distribution （5–7 nm）, large surface area （246 m2/g） and high thermal stability （750–1000 oC）. The luminous property of materials was characterized by Photoluminescence （PL） spectra. The γ-Al2O3：Eu3＋ materials had efficient luminescence, and the emission strength was related to the content of Eu3＋.
