Long-term optical data storage(ODS)technology is essential to break the bottleneck of high energy consumption for information storage in the current era of big data.Here,ODS with an ultralong lifetime of 2×10^(7)...Long-term optical data storage(ODS)technology is essential to break the bottleneck of high energy consumption for information storage in the current era of big data.Here,ODS with an ultralong lifetime of 2×10^(7)years is attained with single ultrafast laser pulse induced reduction of Eu^(3+)ions and tailoring of optical properties inside the Eu-doped aluminosilicate glasses.We demonstrate that the induced local modifications in the glass can stand against the temperature of up to 970 K and strong ultraviolet light irradiation with the power density of 100 kW/cm^(2).Furthermore,the active ions of Eu^(2+)exhibit strong and broadband emission with the full width at half maximum reaching 190 nm,and the photoluminescence(PL)is flexibly tunable in the whole visible region by regulating the alkaline earth metal ions in the glasses.The developed technology and materials will be of great significance in photonic applications such as long-term ODS.展开更多
Low photolumines-cence(PL)quantum yield of molybdenum disulfide(MoS_(2))quan-tum dots(QDs)has lim-ited practical applica-tion as potential fluores-cent materials.Here,we report the intercalation of aluminum ion(Al^(3+...Low photolumines-cence(PL)quantum yield of molybdenum disulfide(MoS_(2))quan-tum dots(QDs)has lim-ited practical applica-tion as potential fluores-cent materials.Here,we report the intercalation of aluminum ion(Al^(3+))to enhance the PL of MoS_(2)QDs and the un-derlying mechanism.With detailed characterization and exciton dynamics study,we suggest that additional surface states including new emission centers have been effectively introduced to MoS_(2)QDs by the Al^(3+)intercalation.The synergy of new radiative pathway for exciton re-combination and the passivation of non-radiative surface traps is responsible for the en-hanced fluorescence of MoS_(2)QDs.Our findings demonstrate an efficient strategy to improve the optical properties of MoS_(2)QDs and are important for understanding the regulation effect of surface states on the emission of two dimensional sulfide QDs.展开更多
Tin halide perovskites recently have attracted extensive research attention due to their similar electronic and band structures but non-toxicity compared with their lead analogues. In this work, we prepare high-qualit...Tin halide perovskites recently have attracted extensive research attention due to their similar electronic and band structures but non-toxicity compared with their lead analogues. In this work, we prepare high-quality CsSnX_(3)(X=Br,I) microplates with lateral sizes of around 1–4 μm by chemical vapor deposition and investigate their low-temperature photoluminescence(PL) properties. A remarkable splitting of PL peaks of the CsSnBr_(3)microplate is observed at low temperatures. Besides the possible structural phase transition at below 70 K, the multi-peak fittings using Gauss functions and the power-dependent saturation phenomenon suggest that the PL could also be influenced by the conversion from the emission of bound excitons into free excitons. With the increase of temperature, the peak position shows a blueshift tendency for CsSnI_(3), which is governed by thermal expansion. However, the peak position of the CsSnBr3microplate exhibits a transition from redshift to blueshift at ~160 K. The full width at half maximum of CsSnX_(3)broadens with increasing temperature, and the fitting results imply that longitudinal optical phonons dominate the electron–phonon coupling and the coupling strength is much more robust in CsSnBr3than in CsSnI_(3). The PL intensity of CsSnX_(3)microplates is suppressed due to the enhanced non-radiative relaxation and exciton dissociation competing with radiative recombination. According to the Arrhenius law, the exciton binding energy of CsSnBr_(3)is ~38.4 meV, slightly smaller than that of CsSnI_(3).展开更多
Type-Ⅱband alignment can realize the efficient charge transfer and separation at the semiconductor heterointerface,which results in photoluminescence(PL)quenching.Recently,several researches demonstrated great enhanc...Type-Ⅱband alignment can realize the efficient charge transfer and separation at the semiconductor heterointerface,which results in photoluminescence(PL)quenching.Recently,several researches demonstrated great enhancement of localized PL at the interface of type-Ⅱtwo-dimensional(2D)heterostructure.However,the dominant physical mechanism of this enhanced PL emission has not been well understood.In this work,we symmetrically study the exciton dynamics of type-Ⅱlateral heterostructures of monolayer MoS_(2) and WS_(2) at room temperatures.The strong PL enhancement along the one-dimensional(1D)heterointerface is associated with the trion emission of the WS_(2) shell,while a dramatic PL quenching of neutral exciton is observed on the MoS_(2) core.The enhanced quantum yield of WS2trion emission can be explained by charge-transfer-enhanced photoexcited carrier dynamics,which is facilitated by resonance hole transfer from MoS_(2) side to WS_(2) side.This work sheds light on the 1D exciton photophysics in lateral heterostructures,which has the potential to lead to new concepts and applications of optoelectronic device.展开更多
Recently, lanthanide-ion-doped luminescent materials have been extensively used as optical thermometry probes due to their fast responses, non-contact, and high sensitivity properties. Based on different responses of ...Recently, lanthanide-ion-doped luminescent materials have been extensively used as optical thermometry probes due to their fast responses, non-contact, and high sensitivity properties. Based on different responses of two emissions to temperature, the fluorescence intensity ratio(FIR) technique can be used to estimate the sensitivities for assessing the optical thermometry performances. In this study, we introduce different doping concentrations of Eu^(3+) ions into negative thermal expansion material Sc2W3O12to increase the thermal-enhanced luminescence from 373 K to 548 K, and investigate the temperature sensing properties in detail. All samples can exhibit their good luminescence behaviors thermally enhanced.The emission intensity of Sc2W3O12:6-mol% Eu3+phosphor reaches 147.8% of initial intensity at 473 K. As the Eu3+doping concentration increases, the resistance of the sample to thermal quenching decreases. The FIR technique based on each of the transitions 5D→7F_(1)(592 nm) and 5D→7F_(2)(613 nm) of Eu3+ions demonstrates a maximum relative temperature sensitivity of 3.063% K-1at 298 K for Sc_(2)W_(3)O_(12):6-mol% Eu3+phosphor. The sensitivity of sample decreases with the increase of Eu3+concentration. Benefiting from the thermal-enhanced luminescence performance and good temperature sensing properties, the Sc_(2)W_(3)O_(12):Eu^(3+)phosphors can be used as optical thermometers.展开更多
Amorphous silicon carbide films are deposited by the plasma enhanced chemical vapour deposition technique,and optical emissions from the near-infrared to the visible are obtained.The optical band gap of the films incr...Amorphous silicon carbide films are deposited by the plasma enhanced chemical vapour deposition technique,and optical emissions from the near-infrared to the visible are obtained.The optical band gap of the films increases from 1.91 eV to 2.92 eV by increasing the carbon content,and the photoluminescence(PL) peak shifts from 1.51 eV to 2.16 eV.The band tail state PL mechanism is confirmed by analysing the optical band gap,PL intensity,the Stocks shift of the PL,and the Urbach energy of the film.The PL decay times of the samples are in the nanosecond scale,and the dependence of the PL lifetime on the emission energy also supports that the optical emission is related to the radiative recombination in the band tail state.展开更多
A series of Zn-Cu-In-S nanocrystals (ZCIS NCs) are prepared and the optical properties of the ZCIS NCs are tuned by adjusting the reaction time. It is interesting to observe that the temperature-dependent photolumin...A series of Zn-Cu-In-S nanocrystals (ZCIS NCs) are prepared and the optical properties of the ZCIS NCs are tuned by adjusting the reaction time. It is interesting to observe that the temperature-dependent photoluminescence (PL) spectra of the ZCIS NCs show a redshift with decreasing intensity at low temperature (50-280 K) and a blueshift at high temperature (318--403 K). The blueshift can be explained by the thermally active phonon-assisted tunneling from the excited states of the low-energy emission band to the excited states of the high-energy emission band.展开更多
Colloidal ZnAgInSe(ZAISe) quantum dots(QDs) with different particle sizes were obtained by accommodating the reaction time. In the previous research, photoluminescence(PL) of ZAISe QDs only could be tuned by cha...Colloidal ZnAgInSe(ZAISe) quantum dots(QDs) with different particle sizes were obtained by accommodating the reaction time. In the previous research, photoluminescence(PL) of ZAISe QDs only could be tuned by changing the composition. In this work the size-tunable photoluminescence was observed successfully. The red shift in the photoluminescence spectra was caused by the quantum confinement effect. The time-resolved photoluminescence indicated that the luminescence mechanisms of the ZAISe QDs were contributed by three recombination processes. Furthermore, the temperature-dependent PL spectra were investigated. We verified the regular change of temperature-dependent PL intensity, peak energy, and the emission linewidth of broadening for ZAISe QDs. According to these fitting data, the activation energy(?E) of ZAISe QDs with different nanocrystal sizes was obtained and the stability of luminescence was discussed.展开更多
Well-crystalline CeO_2 nanowires were prepared via a surfactant-assisted hydrothermal process.Reaction temperature and reaction time were changed for the determination of optimal synthesis parameters.The as-obtained p...Well-crystalline CeO_2 nanowires were prepared via a surfactant-assisted hydrothermal process.Reaction temperature and reaction time were changed for the determination of optimal synthesis parameters.The as-obtained products were characterized by X-ray diffraction (XRD),high-resolution transmission electron microscopy(HRTEM),and field emission scanning electron microscopy(FESEM).The results show that single crystal CeO_2 nanowires with high yield and good uniformity can be obtained hydrothermally at 180℃for 12 h with the aid of 2.0 g surfactant(polyvinyl pyrrolidone,PVP).The role of PVP was then discussed and a possible growth mechanism was proposed. Moreover,room temperature photoluminescence(PL) spectra were obtained for these CeO2 nanowires,which are believed to be related to the abundant defects in these nanostructures.展开更多
Eight neutral mononuclear complexes constructed from transition metals (M = Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Cd(Ⅱ)) and ligands N-(2-pyridylmethyl)-L-phenylalanine (L-Hpmpa) and N-(2-pyridylmethyl)-L...Eight neutral mononuclear complexes constructed from transition metals (M = Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Cd(Ⅱ)) and ligands N-(2-pyridylmethyl)-L-phenylalanine (L-Hpmpa) and N-(2-pyridylmethyl)-L-tyrosine (L-Hpmtyr) have been synthesized by both hydrothermal and conventional room temperature reactions. Four of them have been structurally characterized by single-crystal X-ray diffractions. They are: [Co(L-pmpa)2·2H2O] 1, [Ni(L-pmpa)2·2H2O] 2, [Cu(L-pmpa)2·2H2O] 3 and [Cu(L-pmtyr)2·2H2O] 4. Single-crystal X-ray analysis, IR and elemental analysis revealed that complexes 1, 2 and 3 are isostructural. Powder X-ray diffraction, IR and elemental analysis revealed that complexes 4, 5 (Zn[L-pmtyr]2·2H2O), 6 (Cd[L-pmtyr]2·2H2O), 7 (Co[L-pmtyr]2·2H2O) and 8 (Ni[L-pmtyr]2·2H2O) are isostructural. The photoluminescence properties of L-Hpmtyr ligand, compounds 5 and 6 were also investigated.展开更多
A novel holmium complex [Ho(HIA)_2(H_2O)_4(NO_3)](NO_3)_2(1, HIA = isonicotinic acid) has been synthesized through hydrothermal reactions and characterized by single-crystal X-ray diffraction. Complex 1 crystallizes i...A novel holmium complex [Ho(HIA)_2(H_2O)_4(NO_3)](NO_3)_2(1, HIA = isonicotinic acid) has been synthesized through hydrothermal reactions and characterized by single-crystal X-ray diffraction. Complex 1 crystallizes in the C2/c space group of monoclinic system: a = 14.4797(7), b = 12.4768(2), c = 13.3471(5) ?, β = 118.690(4)°, V = 2115.26(13) ?~3, C_(12)H_(16)HoN_5O_(17), Mr = 667.23, Z = 4, Dc = 2.095 g/cm^3, μ(Mo Kα) = 3.838 mm^(–1) and F(000) = 1304. The crystal structure of 1 is characterized by an isolated structure. Solid-state photoluminescence experiment uncovers that it shows yellow light emission. The emission bands are originated from the characteristic emission of the 4 f electrons intrashell transition of the ~5S_2 → ~5I_8 and ~5F_5 → ~5I_8 of the Ho^(3+) ions. Energy transfer mechanism is explained by the energy level diagram of the Ho3+ ion and the isonicotinic acid ligand. It has remarkable CIE chromaticity coordinates of(0.4929, 0.4632), so it may be a promising color converter for lighting and displays.展开更多
Visible photoluminescence (PL) has been observed from rare earth (Tm, Sm and Dy)-doped AlN films grown by radio-frequency magnetron reactive sputtering. X-ray diffraction indicates that the films are c-axis-orient...Visible photoluminescence (PL) has been observed from rare earth (Tm, Sm and Dy)-doped AlN films grown by radio-frequency magnetron reactive sputtering. X-ray diffraction indicates that the films are c-axis-oriented hexagonal wurtzite type structure with an average crystal size of about 80-110 nm. Room-temperature PL spectra indicate that the blue emission is due to the transition of ^1D2 to ^3F4 and ^1G4 to ^3H6 intra 4f electron of Tm^3+, the yellow emissions of AlN:Sm are due to ^4G5/2 to the ^6HJ (J=5/2, 7/2, 9/2, 11/2) and the reddish emissions of AlN:Dy correspond to the ^4F9/2 to ^6HJ (J=5/2, 13/2, 11/2 and 9/2) and ^6Fll/2 transitions.展开更多
Reaction of ZnCI2 and 4-amino-3,5-propyl-1,2,4-triazole (dpatrz) or CdC12, NaN3 and dpatrz, in aqueous solution at room temperature yields two neutral clusters: a dinuclear complex [Zn2(dpatrz)2Ch] (I) and a li...Reaction of ZnCI2 and 4-amino-3,5-propyl-1,2,4-triazole (dpatrz) or CdC12, NaN3 and dpatrz, in aqueous solution at room temperature yields two neutral clusters: a dinuclear complex [Zn2(dpatrz)2Ch] (I) and a linear trinuclear complex, [Cd3(dpatrz)4(N3)2Cl4] (II). Both complexes have been characterized by X-ray single-crystal diffraction, powder XRD, IR, elemental analysis, TG and fluorescence analysis. Complex I crystallizes in orthorhombic, space group Pbca with a = 11.865(2), b = 14.464(3), c = 15.985(3) A, V= 2743.4(9) A3, Z = 4, C16H32NsCI4Zn2, Mr = 609.4, Dc = 1.475 g.cm3, p = 2.16 mm-1, F(000) = 1248, GOOF = 1.091, the final R = 0.0295 and wR = 0.0665 for 1999 observed reflections (I 〉 2a(/)). Complex Ⅱcrystallizes in monoclinic, space group P2/c with a = 11.408(2), b = 15.211(3), c = 18.152(6) A, fl = 123.75(2)°, V = 2619.1(1) A3, Z = 2, C32H64N22ClaCd3, Mr = 1236.05, Dc = 1.567 g.cm3, p = 1.46 mm-1, F(000) = 1244, GOOF = 1.042, the final R = 0.0444 and wR = 0.0913 for 3466 observed reflections (I 〉 2a(/)). The analysis of X-ray revealed that both structures lie about the inversion centers: complex I adopts two pl,2-triazole bridges linking two Zn(II) ions and II forms a linear trinuclear structure with four μ1,2-triazoles and two/μIA-N3 bridging modes. There are different coordinated geometries for three Cd(II) ions in Ⅱ: one is coordinated with an octahedral environment, and the other two are distorted tetragonal pyramids (r = 0.34). The hydrogen bonds of C-H...C1 and N-H...C1 lead to the discretes into a 3D supramolecular network in both compounds. The thermal stabilities and photoluminescence behaviors of them were also studied.展开更多
Eu^2+-doped Ba3Si6012N2 green phosphors were prepared by microwave assisted sintering method at 1275℃ for 4 h, while the counterparts using conventional solid-state reaction method were synthesized at temperature hi...Eu^2+-doped Ba3Si6012N2 green phosphors were prepared by microwave assisted sintering method at 1275℃ for 4 h, while the counterparts using conventional solid-state reaction method were synthesized at temperature higher than 1300℃ and for to 10 h. Microwave assisted sintering could reduce the activation energy and enhance the diffu- sion rate, thus greatly improved the sintering. Moreover, the influence of Si3N4 content on phase formation, morphol- ogy, absorption, and quantum efficiency, and photoluminescence properties of phosphors were studied. As a result, the Ba3Si6OI2N2:Eu^2+ samples sintered by microwave assisted sintering method have a higher phase purity and photo- luminescence intensity under ultraviolet excitation as compared with samples sintered in the conventional tube furnace The proposed method is a potential preparation method for the oxynitride phosphors with strong photoluminescence and high phase purity.展开更多
A novel terbium-mercury complex [Tb(IA)3(H3 O)2]2 n(2 n HgCl4)(n Hg2 Cl5)·n H3 O· 3 n H2 O(1, HIA = isonicotinic acid) has been synthesized through hydrothermal reactions and characterized by single-crystal ...A novel terbium-mercury complex [Tb(IA)3(H3 O)2]2 n(2 n HgCl4)(n Hg2 Cl5)·n H3 O· 3 n H2 O(1, HIA = isonicotinic acid) has been synthesized through hydrothermal reactions and characterized by single-crystal X-ray diffraction. Complex 1 crystallizes in the C2/c space group of monoclinic system with a = 24.2347(5), b = 20.8342(6), c = 15.3206(3) ?, β = 128.257(2)°, V = 6074.3(2) ?3, C36H41Cl13Hg4N6O20Tb2, Mr = 2458.80, Z = 4, Dc = 2.689 g/cm3, μ(Mo Kα) = 13.014 mm–1 and F(000) = 4520. The crystal structure of 1 is characterized by a one-dimensional(1-D) chain-like structure. Solid-state UV/Vis diffuse reflectance spectrum reveals the existence of a wide optical band gap of 3.36 eV. Solid-state photoluminescence experiment uncovers that it shows reddish brown upconversion emission. The emission bands are originated from the characteristic emission of the 4 f electrons intrashell transition of the 5D4 → 7 FJ(J = 6, 5, 4) of the Tb3+ ions. Energy transfer mechanism is explained by the energy level diagram of the Tb3+ ion and the isonicotinic acid ligand. It shows a remarkable CIE chromaticity coordinates(0.4158, 0.4005).展开更多
Dipyrido [3, 2-a:2,3-c] phenazine moiety has been introduced as neutral ligand in europium complex. Therefore, a new europium complex with saturated emission, strong fluorescent intensity and good solubility was desi...Dipyrido [3, 2-a:2,3-c] phenazine moiety has been introduced as neutral ligand in europium complex. Therefore, a new europium complex with saturated emission, strong fluorescent intensity and good solubility was designed and synthesized for the first time. Its photoluminescence and UV properties were examined. The experimental results showed that this new Eu-complex could be used as red electroluminescent materials.展开更多
In this paper the multiwalled carbon nanotubes (MWNTs) were synthesized by a chemical vapour deposition and the SEM graph shows that the sample has good construction. The micro-Raman spectrum shows the characteristi...In this paper the multiwalled carbon nanotubes (MWNTs) were synthesized by a chemical vapour deposition and the SEM graph shows that the sample has good construction. The micro-Raman spectrum shows the characteristic line of the MWNTs and an additional line produced by the defects on the outer surface of MWNTs. The photoluminescence (PL) spectra observed experimentally are variable under different excitation wavelengths and the strong excitation wavelength dependence of luminescence indicates a distribution of emitters which include electron π in excited states and the Van Hove singularities. The absorption spectra confirm the transition channels which are consistent with the PL emission.展开更多
Ce^(3+)/Tb^(3+) co-doped and Ce^(3+)/Tb^(3+)/Eu^(3+) tri-doped β-NaYF_(4) photoluminescent microcrystals using oleic acid as surfactant were synthesized using the solvothermal method.Their microstructural characteris...Ce^(3+)/Tb^(3+) co-doped and Ce^(3+)/Tb^(3+)/Eu^(3+) tri-doped β-NaYF_(4) photoluminescent microcrystals using oleic acid as surfactant were synthesized using the solvothermal method.Their microstructural characteristics and photoluminescence properties were investigated in detail.They have the shape of hexagonal prism bipyramids with uniform particle size,which decreases with the concentrations of Tb^(3+) and Eu^(3+).The energy transfer processes of both the Ce^(3+)→Tb^(3+) and the Ce^(3+)→Tb^(3+)→Eu^(3+) were systematically studied.Compared with Eu^(3+) or Tb^(3+) single-doped β-NaYF_(4) microcrystals,the sensitization by Ce^(3+) for the photoluminescence of Tb^(3+) and Eu^(3+) leads to a broad excitation spectral bandwidth in the ultraviolet (UV) range.Meanwhile,the corresponding optical absorption efficiency is greatly enhanced.High energy transfer efficiencies have been observed from Ce^(3+) to Tb^(3+) and from Tb^(3+) to Eu^(3+).展开更多
Two new europium (Ⅲ) coordination polymers formulated as Eu2(H20)a(ox)4]· (CsH6N)2-2H20 (1) and Eu2(ad)3(H20)4]'0.25H20 (2) (H20x = oxalic acid, H2ad = adipic acid) have been synthesized from ...Two new europium (Ⅲ) coordination polymers formulated as Eu2(H20)a(ox)4]· (CsH6N)2-2H20 (1) and Eu2(ad)3(H20)4]'0.25H20 (2) (H20x = oxalic acid, H2ad = adipic acid) have been synthesized from the self-assembly of lanthanide ions Eu^3+ with flexible oxalic and adipic acid ligands, respectively. Structural analyses revealed that complex 1 exhibits three-dimensional metalorganic frameworks, and 2 has intricate two-dimensional interpenetrated metal-organic networks. In addition, the photoluminescent properties of complexes 1 and 2 were discussed in detail, which shows strong red emission, corresponding to ^5Do →^7F? transition of Eu^3+ ions.展开更多
基金supports from the National Key R&D Program of China (No. 2021YFB2802000 and 2021YFB2800500)the National Natural Science Foundation of China (Grant Nos. U20A20211, 51902286, 61775192, 61905215, and 62005164)+2 种基金Key Research Project of Zhejiang Labthe State Key Laboratory of High Field Laser Physics (Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences)China Postdoctoral Science Foundation (2021M702799)。
文摘Long-term optical data storage(ODS)technology is essential to break the bottleneck of high energy consumption for information storage in the current era of big data.Here,ODS with an ultralong lifetime of 2×10^(7)years is attained with single ultrafast laser pulse induced reduction of Eu^(3+)ions and tailoring of optical properties inside the Eu-doped aluminosilicate glasses.We demonstrate that the induced local modifications in the glass can stand against the temperature of up to 970 K and strong ultraviolet light irradiation with the power density of 100 kW/cm^(2).Furthermore,the active ions of Eu^(2+)exhibit strong and broadband emission with the full width at half maximum reaching 190 nm,and the photoluminescence(PL)is flexibly tunable in the whole visible region by regulating the alkaline earth metal ions in the glasses.The developed technology and materials will be of great significance in photonic applications such as long-term ODS.
基金supported by the National Natural Sci-ence Foundation of China(No.12004101,No.61905066,No.22103024,No.61805070,and No.22105063)the Nat-ural Science Foundation of Henan Province(No.202300410065)the Open Project of the State Key Laboratory of Crop Stress Adaptation and Im-provement.
文摘Low photolumines-cence(PL)quantum yield of molybdenum disulfide(MoS_(2))quan-tum dots(QDs)has lim-ited practical applica-tion as potential fluores-cent materials.Here,we report the intercalation of aluminum ion(Al^(3+))to enhance the PL of MoS_(2)QDs and the un-derlying mechanism.With detailed characterization and exciton dynamics study,we suggest that additional surface states including new emission centers have been effectively introduced to MoS_(2)QDs by the Al^(3+)intercalation.The synergy of new radiative pathway for exciton re-combination and the passivation of non-radiative surface traps is responsible for the en-hanced fluorescence of MoS_(2)QDs.Our findings demonstrate an efficient strategy to improve the optical properties of MoS_(2)QDs and are important for understanding the regulation effect of surface states on the emission of two dimensional sulfide QDs.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11974279, 12074311, 12004310, and 12261141662)。
文摘Tin halide perovskites recently have attracted extensive research attention due to their similar electronic and band structures but non-toxicity compared with their lead analogues. In this work, we prepare high-quality CsSnX_(3)(X=Br,I) microplates with lateral sizes of around 1–4 μm by chemical vapor deposition and investigate their low-temperature photoluminescence(PL) properties. A remarkable splitting of PL peaks of the CsSnBr_(3)microplate is observed at low temperatures. Besides the possible structural phase transition at below 70 K, the multi-peak fittings using Gauss functions and the power-dependent saturation phenomenon suggest that the PL could also be influenced by the conversion from the emission of bound excitons into free excitons. With the increase of temperature, the peak position shows a blueshift tendency for CsSnI_(3), which is governed by thermal expansion. However, the peak position of the CsSnBr3microplate exhibits a transition from redshift to blueshift at ~160 K. The full width at half maximum of CsSnX_(3)broadens with increasing temperature, and the fitting results imply that longitudinal optical phonons dominate the electron–phonon coupling and the coupling strength is much more robust in CsSnBr3than in CsSnI_(3). The PL intensity of CsSnX_(3)microplates is suppressed due to the enhanced non-radiative relaxation and exciton dissociation competing with radiative recombination. According to the Arrhenius law, the exciton binding energy of CsSnBr_(3)is ~38.4 meV, slightly smaller than that of CsSnI_(3).
基金Project supported by the National Natural Science Foundation of China(Grant No.61804047)the Training Program for the Natural Science Foundation of Henan Normal University,China(Grant No.2017PL02)+2 种基金the Scientific Research Start-up Foundation for Ph D of Chaohu University,China(Grant No.KYQD-2023012)the Natural Science Foundation Henan Province of China(Grant No.232300421236)the High Performance Computing Center(HPCC)of Henan Normal University,China。
文摘Type-Ⅱband alignment can realize the efficient charge transfer and separation at the semiconductor heterointerface,which results in photoluminescence(PL)quenching.Recently,several researches demonstrated great enhancement of localized PL at the interface of type-Ⅱtwo-dimensional(2D)heterostructure.However,the dominant physical mechanism of this enhanced PL emission has not been well understood.In this work,we symmetrically study the exciton dynamics of type-Ⅱlateral heterostructures of monolayer MoS_(2) and WS_(2) at room temperatures.The strong PL enhancement along the one-dimensional(1D)heterointerface is associated with the trion emission of the WS_(2) shell,while a dramatic PL quenching of neutral exciton is observed on the MoS_(2) core.The enhanced quantum yield of WS2trion emission can be explained by charge-transfer-enhanced photoexcited carrier dynamics,which is facilitated by resonance hole transfer from MoS_(2) side to WS_(2) side.This work sheds light on the 1D exciton photophysics in lateral heterostructures,which has the potential to lead to new concepts and applications of optoelectronic device.
基金supported by the National Natural Science Foundation of China (Grant No. 51872327)。
文摘Recently, lanthanide-ion-doped luminescent materials have been extensively used as optical thermometry probes due to their fast responses, non-contact, and high sensitivity properties. Based on different responses of two emissions to temperature, the fluorescence intensity ratio(FIR) technique can be used to estimate the sensitivities for assessing the optical thermometry performances. In this study, we introduce different doping concentrations of Eu^(3+) ions into negative thermal expansion material Sc2W3O12to increase the thermal-enhanced luminescence from 373 K to 548 K, and investigate the temperature sensing properties in detail. All samples can exhibit their good luminescence behaviors thermally enhanced.The emission intensity of Sc2W3O12:6-mol% Eu3+phosphor reaches 147.8% of initial intensity at 473 K. As the Eu3+doping concentration increases, the resistance of the sample to thermal quenching decreases. The FIR technique based on each of the transitions 5D→7F_(1)(592 nm) and 5D→7F_(2)(613 nm) of Eu3+ions demonstrates a maximum relative temperature sensitivity of 3.063% K-1at 298 K for Sc_(2)W_(3)O_(12):6-mol% Eu3+phosphor. The sensitivity of sample decreases with the increase of Eu3+concentration. Benefiting from the thermal-enhanced luminescence performance and good temperature sensing properties, the Sc_(2)W_(3)O_(12):Eu^(3+)phosphors can be used as optical thermometers.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60878040)the Natural Science Foundation of Hebei Province,China (Grant Nos. F2012201007 and F2012201042)
文摘Amorphous silicon carbide films are deposited by the plasma enhanced chemical vapour deposition technique,and optical emissions from the near-infrared to the visible are obtained.The optical band gap of the films increases from 1.91 eV to 2.92 eV by increasing the carbon content,and the photoluminescence(PL) peak shifts from 1.51 eV to 2.16 eV.The band tail state PL mechanism is confirmed by analysing the optical band gap,PL intensity,the Stocks shift of the PL,and the Urbach energy of the film.The PL decay times of the samples are in the nanosecond scale,and the dependence of the PL lifetime on the emission energy also supports that the optical emission is related to the radiative recombination in the band tail state.
基金supported by the National Natural Science Foundation of China(Grand Nos.60907021,60977035,and 60877029)the Natural Science Foundation of Tianjin,China(Grant No.11JCYBJC00300)
文摘A series of Zn-Cu-In-S nanocrystals (ZCIS NCs) are prepared and the optical properties of the ZCIS NCs are tuned by adjusting the reaction time. It is interesting to observe that the temperature-dependent photoluminescence (PL) spectra of the ZCIS NCs show a redshift with decreasing intensity at low temperature (50-280 K) and a blueshift at high temperature (318--403 K). The blueshift can be explained by the thermally active phonon-assisted tunneling from the excited states of the low-energy emission band to the excited states of the high-energy emission band.
基金supported by the National High Technology Research and Development Program of China(Grant No.2013AA014201)the National Key Foundation for Exploring Scientific Instrument of China(Grant No.2014YQ120351)the Natural Science Foundation of Tianjin(Grant No.11JCYBJC00300,4JCZDJC31200,15JCYBJC16700,and 15JCYBJC16800)
文摘Colloidal ZnAgInSe(ZAISe) quantum dots(QDs) with different particle sizes were obtained by accommodating the reaction time. In the previous research, photoluminescence(PL) of ZAISe QDs only could be tuned by changing the composition. In this work the size-tunable photoluminescence was observed successfully. The red shift in the photoluminescence spectra was caused by the quantum confinement effect. The time-resolved photoluminescence indicated that the luminescence mechanisms of the ZAISe QDs were contributed by three recombination processes. Furthermore, the temperature-dependent PL spectra were investigated. We verified the regular change of temperature-dependent PL intensity, peak energy, and the emission linewidth of broadening for ZAISe QDs. According to these fitting data, the activation energy(?E) of ZAISe QDs with different nanocrystal sizes was obtained and the stability of luminescence was discussed.
基金supported by the National Natural Science Foundation of China(Nos.50901074 and 50672001)the Young Teacher Natural Science Fund of Anhui Province,China(No.2008jq1002).
文摘Well-crystalline CeO_2 nanowires were prepared via a surfactant-assisted hydrothermal process.Reaction temperature and reaction time were changed for the determination of optimal synthesis parameters.The as-obtained products were characterized by X-ray diffraction (XRD),high-resolution transmission electron microscopy(HRTEM),and field emission scanning electron microscopy(FESEM).The results show that single crystal CeO_2 nanowires with high yield and good uniformity can be obtained hydrothermally at 180℃for 12 h with the aid of 2.0 g surfactant(polyvinyl pyrrolidone,PVP).The role of PVP was then discussed and a possible growth mechanism was proposed. Moreover,room temperature photoluminescence(PL) spectra were obtained for these CeO2 nanowires,which are believed to be related to the abundant defects in these nanostructures.
基金Supported by the 973 Program (2006CB932903, 2007CB815303)NNSFC, NSF of Fujian Province (2006F3134)+1 种基金"One Hundred Talent Project"Key Projects from CAS
文摘Eight neutral mononuclear complexes constructed from transition metals (M = Co(Ⅱ), Ni(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Cd(Ⅱ)) and ligands N-(2-pyridylmethyl)-L-phenylalanine (L-Hpmpa) and N-(2-pyridylmethyl)-L-tyrosine (L-Hpmtyr) have been synthesized by both hydrothermal and conventional room temperature reactions. Four of them have been structurally characterized by single-crystal X-ray diffractions. They are: [Co(L-pmpa)2·2H2O] 1, [Ni(L-pmpa)2·2H2O] 2, [Cu(L-pmpa)2·2H2O] 3 and [Cu(L-pmtyr)2·2H2O] 4. Single-crystal X-ray analysis, IR and elemental analysis revealed that complexes 1, 2 and 3 are isostructural. Powder X-ray diffraction, IR and elemental analysis revealed that complexes 4, 5 (Zn[L-pmtyr]2·2H2O), 6 (Cd[L-pmtyr]2·2H2O), 7 (Co[L-pmtyr]2·2H2O) and 8 (Ni[L-pmtyr]2·2H2O) are isostructural. The photoluminescence properties of L-Hpmtyr ligand, compounds 5 and 6 were also investigated.
基金supported by the NNSFC(21361013)Jiangxi Provincial Department of Education’s Item of Science and Technology(GJJ170637)+1 种基金the open foundation(20180008)of the State Key Laboratory of Structural Chemistry,Fujian Institute of Research on the Structure of Matter,Chinese Academy of Sciencesthe open foundation(ST201522007)of the Key Laboratory of Jiangxi Province for Persistant Pollutants Control and Resources Recycle(Nanchang Hangkong University)
文摘A novel holmium complex [Ho(HIA)_2(H_2O)_4(NO_3)](NO_3)_2(1, HIA = isonicotinic acid) has been synthesized through hydrothermal reactions and characterized by single-crystal X-ray diffraction. Complex 1 crystallizes in the C2/c space group of monoclinic system: a = 14.4797(7), b = 12.4768(2), c = 13.3471(5) ?, β = 118.690(4)°, V = 2115.26(13) ?~3, C_(12)H_(16)HoN_5O_(17), Mr = 667.23, Z = 4, Dc = 2.095 g/cm^3, μ(Mo Kα) = 3.838 mm^(–1) and F(000) = 1304. The crystal structure of 1 is characterized by an isolated structure. Solid-state photoluminescence experiment uncovers that it shows yellow light emission. The emission bands are originated from the characteristic emission of the 4 f electrons intrashell transition of the ~5S_2 → ~5I_8 and ~5F_5 → ~5I_8 of the Ho^(3+) ions. Energy transfer mechanism is explained by the energy level diagram of the Ho3+ ion and the isonicotinic acid ligand. It has remarkable CIE chromaticity coordinates of(0.4929, 0.4632), so it may be a promising color converter for lighting and displays.
基金Project supported by the National Natural Science Foundation of China (Grant No 50372082).
文摘Visible photoluminescence (PL) has been observed from rare earth (Tm, Sm and Dy)-doped AlN films grown by radio-frequency magnetron reactive sputtering. X-ray diffraction indicates that the films are c-axis-oriented hexagonal wurtzite type structure with an average crystal size of about 80-110 nm. Room-temperature PL spectra indicate that the blue emission is due to the transition of ^1D2 to ^3F4 and ^1G4 to ^3H6 intra 4f electron of Tm^3+, the yellow emissions of AlN:Sm are due to ^4G5/2 to the ^6HJ (J=5/2, 7/2, 9/2, 11/2) and the reddish emissions of AlN:Dy correspond to the ^4F9/2 to ^6HJ (J=5/2, 13/2, 11/2 and 9/2) and ^6Fll/2 transitions.
基金Supported by the National Natural Science Foundation of China(No.21271121)SRFDP(No.20111401110002)Shanxi Scholarship Council of China(2013-026)
文摘Reaction of ZnCI2 and 4-amino-3,5-propyl-1,2,4-triazole (dpatrz) or CdC12, NaN3 and dpatrz, in aqueous solution at room temperature yields two neutral clusters: a dinuclear complex [Zn2(dpatrz)2Ch] (I) and a linear trinuclear complex, [Cd3(dpatrz)4(N3)2Cl4] (II). Both complexes have been characterized by X-ray single-crystal diffraction, powder XRD, IR, elemental analysis, TG and fluorescence analysis. Complex I crystallizes in orthorhombic, space group Pbca with a = 11.865(2), b = 14.464(3), c = 15.985(3) A, V= 2743.4(9) A3, Z = 4, C16H32NsCI4Zn2, Mr = 609.4, Dc = 1.475 g.cm3, p = 2.16 mm-1, F(000) = 1248, GOOF = 1.091, the final R = 0.0295 and wR = 0.0665 for 1999 observed reflections (I 〉 2a(/)). Complex Ⅱcrystallizes in monoclinic, space group P2/c with a = 11.408(2), b = 15.211(3), c = 18.152(6) A, fl = 123.75(2)°, V = 2619.1(1) A3, Z = 2, C32H64N22ClaCd3, Mr = 1236.05, Dc = 1.567 g.cm3, p = 1.46 mm-1, F(000) = 1244, GOOF = 1.042, the final R = 0.0444 and wR = 0.0913 for 3466 observed reflections (I 〉 2a(/)). The analysis of X-ray revealed that both structures lie about the inversion centers: complex I adopts two pl,2-triazole bridges linking two Zn(II) ions and II forms a linear trinuclear structure with four μ1,2-triazoles and two/μIA-N3 bridging modes. There are different coordinated geometries for three Cd(II) ions in Ⅱ: one is coordinated with an octahedral environment, and the other two are distorted tetragonal pyramids (r = 0.34). The hydrogen bonds of C-H...C1 and N-H...C1 lead to the discretes into a 3D supramolecular network in both compounds. The thermal stabilities and photoluminescence behaviors of them were also studied.
文摘Eu^2+-doped Ba3Si6012N2 green phosphors were prepared by microwave assisted sintering method at 1275℃ for 4 h, while the counterparts using conventional solid-state reaction method were synthesized at temperature higher than 1300℃ and for to 10 h. Microwave assisted sintering could reduce the activation energy and enhance the diffu- sion rate, thus greatly improved the sintering. Moreover, the influence of Si3N4 content on phase formation, morphol- ogy, absorption, and quantum efficiency, and photoluminescence properties of phosphors were studied. As a result, the Ba3Si6OI2N2:Eu^2+ samples sintered by microwave assisted sintering method have a higher phase purity and photo- luminescence intensity under ultraviolet excitation as compared with samples sintered in the conventional tube furnace The proposed method is a potential preparation method for the oxynitride phosphors with strong photoluminescence and high phase purity.
基金Supported by the NSF of China(21361013,31460488)NSF of Fujian(2018J01447)+1 种基金Jiangxi Provincial Department of Education’s Item of Science and Technology(GJJ170637)the Open Foundation(20180008)of State Key Laboratory of Structural Chemistry
文摘A novel terbium-mercury complex [Tb(IA)3(H3 O)2]2 n(2 n HgCl4)(n Hg2 Cl5)·n H3 O· 3 n H2 O(1, HIA = isonicotinic acid) has been synthesized through hydrothermal reactions and characterized by single-crystal X-ray diffraction. Complex 1 crystallizes in the C2/c space group of monoclinic system with a = 24.2347(5), b = 20.8342(6), c = 15.3206(3) ?, β = 128.257(2)°, V = 6074.3(2) ?3, C36H41Cl13Hg4N6O20Tb2, Mr = 2458.80, Z = 4, Dc = 2.689 g/cm3, μ(Mo Kα) = 13.014 mm–1 and F(000) = 4520. The crystal structure of 1 is characterized by a one-dimensional(1-D) chain-like structure. Solid-state UV/Vis diffuse reflectance spectrum reveals the existence of a wide optical band gap of 3.36 eV. Solid-state photoluminescence experiment uncovers that it shows reddish brown upconversion emission. The emission bands are originated from the characteristic emission of the 4 f electrons intrashell transition of the 5D4 → 7 FJ(J = 6, 5, 4) of the Tb3+ ions. Energy transfer mechanism is explained by the energy level diagram of the Tb3+ ion and the isonicotinic acid ligand. It shows a remarkable CIE chromaticity coordinates(0.4158, 0.4005).
基金This work was supported by the National Natural Science Foundation of China (No29992530-6) and Provincial Natural Science Foundation of Hunan (00JJY2043).
文摘Dipyrido [3, 2-a:2,3-c] phenazine moiety has been introduced as neutral ligand in europium complex. Therefore, a new europium complex with saturated emission, strong fluorescent intensity and good solubility was designed and synthesized for the first time. Its photoluminescence and UV properties were examined. The experimental results showed that this new Eu-complex could be used as red electroluminescent materials.
文摘In this paper the multiwalled carbon nanotubes (MWNTs) were synthesized by a chemical vapour deposition and the SEM graph shows that the sample has good construction. The micro-Raman spectrum shows the characteristic line of the MWNTs and an additional line produced by the defects on the outer surface of MWNTs. The photoluminescence (PL) spectra observed experimentally are variable under different excitation wavelengths and the strong excitation wavelength dependence of luminescence indicates a distribution of emitters which include electron π in excited states and the Van Hove singularities. The absorption spectra confirm the transition channels which are consistent with the PL emission.
基金Funded by the National Natural Science Foundation of China(Nos.21571095,51362020)the Jiangxi Provincial Department of Education(No.KJLD13008)the Scientific Research Projects of Hunan Education Department(No.18C1442)。
文摘Ce^(3+)/Tb^(3+) co-doped and Ce^(3+)/Tb^(3+)/Eu^(3+) tri-doped β-NaYF_(4) photoluminescent microcrystals using oleic acid as surfactant were synthesized using the solvothermal method.Their microstructural characteristics and photoluminescence properties were investigated in detail.They have the shape of hexagonal prism bipyramids with uniform particle size,which decreases with the concentrations of Tb^(3+) and Eu^(3+).The energy transfer processes of both the Ce^(3+)→Tb^(3+) and the Ce^(3+)→Tb^(3+)→Eu^(3+) were systematically studied.Compared with Eu^(3+) or Tb^(3+) single-doped β-NaYF_(4) microcrystals,the sensitization by Ce^(3+) for the photoluminescence of Tb^(3+) and Eu^(3+) leads to a broad excitation spectral bandwidth in the ultraviolet (UV) range.Meanwhile,the corresponding optical absorption efficiency is greatly enhanced.High energy transfer efficiencies have been observed from Ce^(3+) to Tb^(3+) and from Tb^(3+) to Eu^(3+).
基金This work was supported by the National Natural Science Foundation of China(No.20272014)the Project of National Education Ministry(Project No.204097)National 973 Project of China(Project No.2002CB613400-5).
基金The project was supported by the scientific and technological department of Henan Province (No. 102300410269)
文摘Two new europium (Ⅲ) coordination polymers formulated as Eu2(H20)a(ox)4]· (CsH6N)2-2H20 (1) and Eu2(ad)3(H20)4]'0.25H20 (2) (H20x = oxalic acid, H2ad = adipic acid) have been synthesized from the self-assembly of lanthanide ions Eu^3+ with flexible oxalic and adipic acid ligands, respectively. Structural analyses revealed that complex 1 exhibits three-dimensional metalorganic frameworks, and 2 has intricate two-dimensional interpenetrated metal-organic networks. In addition, the photoluminescent properties of complexes 1 and 2 were discussed in detail, which shows strong red emission, corresponding to ^5Do →^7F? transition of Eu^3+ ions.