InAsN nanowires on InAs stems were obtained using plasma-assisted molecular beam epitaxy on a SiOx/Si(111)sub-strate.Also,heterostructured InAs/InAsN and InAsN/InP nanowires were grown in the core/shell geometry.In th...InAsN nanowires on InAs stems were obtained using plasma-assisted molecular beam epitaxy on a SiOx/Si(111)sub-strate.Also,heterostructured InAs/InAsN and InAsN/InP nanowires were grown in the core/shell geometry.In the low-temperature photoluminescence spectra of the grown structures,spectral features are observed that correspond to the polytypic structure of nanowires with a predominance of the wurtzite phase and parasitic islands of the sphalerite phase.It was shown that the interband photoluminescence spectral features of InAsN nanowires experience a red shift relative to the pristine InAs nanowires.The incorporation of nitrogen reduces the bandgap by splitting the conduction band into two subbands.The position of the spectral features in the photoluminescence spectra confirms the formation of a nitride solid solution with a poly-typic hexagonal structure,having a concentration of nitrogen atoms of up to 0.7%.Additional passivation of the nanowire surface with InP leads to a decrease in the intensity of nonradiative recombination and an improvement in the photoluminescent response of the nanowires,which makes it possible to detect photoluminescence emission at room temperature.Thus,by changing the composition and morphology of nanowires,it is possible to control their electronic structure,which allows varying the operating range of detectors and mid-IR radiation sources based on them.展开更多
Ultraviolet upconversion photoluminescence materials have great potential in various fields,but the improvement of the upconversion efficiency is challenging.Codoping of Li^(+)is considered as an effective strategy an...Ultraviolet upconversion photoluminescence materials have great potential in various fields,but the improvement of the upconversion efficiency is challenging.Codoping of Li^(+)is considered as an effective strategy and widely used to improve the photoluminescence properties of phosphors.In this paper,Li^(+)is introduced into a Y_(7)O_(6)F_(9):Pr^(3+),Gd^(3+)system.The effect of Li^(+)codoping on the phase purity,crystal structure,micro structure,downshifting and upconversion photo luminescence as well as the decay dynamic of the phosphors was studied.It is revealed that the overall photoluminescence efficiency and the energy transfer efficiency from pr^(3+)to Gd^(3+)are greatly promoted.The downshifting and upconversion photoluminescence increase by 2.58 and 10 times as 6 mol%of Li^(+)is codoped.The photo luminescence decay dynamic study shows that the ^(3)P_(0)state decays slower in the Li^(+)-containing phosphor than the Li^(+)-free one.The improvement of the photoluminescence properties is due to the increase of the crystallinity and the reduce of the quenching center.展开更多
Nano phosphors of 2%Dy^(3+)(wt%)doped La_(2)MgTiO_(6) and monovalent/divalent/trivalent co-doped La_(1.98)Dy_(0.02)MgTiO_(6):x%A^(y+)(A^(y+):Li+,Ba^(2+),Sr^(2+),Bi^(3+),and Sm^(3+);0≤x≤2 wt%)were synthesized by comb...Nano phosphors of 2%Dy^(3+)(wt%)doped La_(2)MgTiO_(6) and monovalent/divalent/trivalent co-doped La_(1.98)Dy_(0.02)MgTiO_(6):x%A^(y+)(A^(y+):Li+,Ba^(2+),Sr^(2+),Bi^(3+),and Sm^(3+);0≤x≤2 wt%)were synthesized by combustion method.From the XRD data,it is deduced that an increase in the valency of co-dopant increases the crystallinity of the double perovskite orthorhombic nanocrystal structure.With an increase in co-dopant size,an elevation in optical bandgap is visible with the highest bandgap of 3.835 eV for Bi^(3+).The photo-absorption is monotonically broadened for Sr^(2+),Sm^(3+),and Li+around 200-450 nm.Under351 nm,Dy^(3+)triggered lattice shows major characteristic emission peaks at 480 nm(^(4)F_(9/2)→^(6)H_(15/2)),574 nm(^(4)F_(9/2)→^(6)H_(13/2)),and 670 nm(^(4)F_(9/2)→^(6)H_(11/2)).leading to near white light emission with CIE coordinates(0.341,0.376).Upon co-doping,the PL intensity is significantly increased with maximum emission for trivalent Sm^(3+),followed by divalent Sr^(2+)and monovalent Li+respectively.With increasing excitation wavelength,Sr^(2+)shows a dominated output and it is found that divalent Sr^(2+)is a potential codopant that could enhance luminescence intensity up to 6 times with a Sr^(2+)→Dy^(3+)energy transfer efficiency of 86%.It is specified that the CIE coordinates of Li+co-doped samples show ideal white emission with color coordinates(0.333,0.336).The concluding outcomes signify the noblest rare earth Sm^(3+)co-doping and thus Sm^(3+)→Dy^(3+)energy transfer mechanism is discussed in detail.展开更多
In this research study,magnesium-aluminum(Mg-Al)bimetallic oxide powders are synthesized via the sol-gel auto combustion method using diethanolamine(DEA)as the fuel.In order to subsequently determine the influence of ...In this research study,magnesium-aluminum(Mg-Al)bimetallic oxide powders are synthesized via the sol-gel auto combustion method using diethanolamine(DEA)as the fuel.In order to subsequently determine the influence of calcination temperatures upon the structure,chemical bonding,morphology,optical properties,and fluorescence properties of the as-synthesized and calcined Mg-Al bimetallic oxide powders,the researcher employed X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),transmission electron microscopy(TEM),UV–visible diffuse reflectance spectroscopy(UV-DRS),and photoluminescence spectroscopy(PL),respectively.It was apparent on the basis of the XRD and FT-IR analyses that those powders undergoing calcination at temperatures of 500℃,700℃,and 900℃contained the major phase magnesium aluminate(Mg Al_(2)O_(4))spinel with trace magnesium oxide(Mg O)and hydrotalcite(Mg_(6)Al_(2)(CO_(3))(OH)_(16)).When the calcination temperature rose to 1100℃,this resulted in a single phase MgAl_(2)O_(4)while MgO and(Mg_(6)Al_(2)(CO_(3))(OH)_(16))were no longer observed.UV-DRS analysis revealed that in optimized conditions,calcination resulted in better sample absorption and reflection levels when compared to the ultraviolet,visible,and infrared spectra observed in the case of the as-synthesized sample.The bandgap energy(E_(g))for calcined samples was in the range of 2.65 e V to 5.85 e V,in contrast to the value of 4.10 e V for the as-synthesized sample.Analysis of photoluminescence showed that for the as-synthesized samples and those calcined at low temperatures,visible light was emitted only in the violet,blue,and green regions with low intensity,while for samples calcined at higher temperatures,the emissions showed greater intensity and extended to the yellow and orange regions.Multiple defect centers were found in the bandgap which can explain these findings.展开更多
Achieving high-efficiency photoluminescence in trivalent lanthanides(Ln^(3+))requires precise crystalfield perturbation to overcome parity-forbidden 4f-transitions and suppress nonradiative decay.However,realizing suc...Achieving high-efficiency photoluminescence in trivalent lanthanides(Ln^(3+))requires precise crystalfield perturbation to overcome parity-forbidden 4f-transitions and suppress nonradiative decay.However,realizing such control remains challenging,even in well-optimized Ln^(3+) -doped nanocrystals.Here,by exploiting the atomically precise structure of metal nanoclusters,we demonstrate symmetry engineering in the Eu_(2)Ti_(4) nanoclusters through stepwise ligand substitution(BA/Phen→FBA/Phen→FBA/Bpy.BA:benzoicacid;Phen:1,10-phenanthroline;FBA:p-fluorobenzoicacid;Bpy:2,2'-bipyridine).The incorporation of FBA effectively suppresses nonradiative relaxation,while the flexible Bpy ligand induces symmetry reduction from D_(2d) to C_(2v) through coordination modulation,yielding a high photoluminescence quantum yield(PLQY)of 91.2%in the Ln^(3+) cluster systems.The transient-absorption,Judd-Ofelt theory,crystal-field analysis,and temperature-dependent photophysical studies elucidated the underlying modulation mechanisms.Furthermore,these clusters exhibit promising potential for optoelectronic applications,offering a new design strategy for high-performance luminescent materials.展开更多
There is a growing interest in the rapid assessment of terahertz(THz)spectroscopy owing to its promising application pros-pects in nondestructive testing,security screening,and communication.In this study,we introduce...There is a growing interest in the rapid assessment of terahertz(THz)spectroscopy owing to its promising application pros-pects in nondestructive testing,security screening,and communication.In this study,we introduce a swift characterization method for THz spectroscopy that utilizes a THz-to-optical conversion system in a warm atomic vapor cell.By subtracting the photoluminescence(PL)spectra of cesium atoms with the THz field from those without the THz field,we obtained differential PL spectra that effectively characterized the 0.548 THz field.The differential PL spectra of Rydberg atoms offer the opportunity to quantify the THz field’s intensity and frequency,potentially paving the way for the development of THz spectroscopy based on warm atomic vapor cells.展开更多
Two-dimensional(2D)chiral halide perovskites(CHPs)have attracted broad interest due to their distinct spin-dependent properties and promising applications in chiroptics and spintronics.Here,we report a new type of 2D ...Two-dimensional(2D)chiral halide perovskites(CHPs)have attracted broad interest due to their distinct spin-dependent properties and promising applications in chiroptics and spintronics.Here,we report a new type of 2D CHP single crystals,namely R/S-3BrMBA_(2)PbBr_(4).The chirality of the as-prepared samples is confirmed by exploiting circular dichroism spectroscopy,indicating a successful chirality transfer from chiral organic cations to their inorganic perovskite sublattices.Furthermore,we observed bright photoluminescence spanning from 380 to 750 nm in R/S-3BrMBA_(2)PbBr_(4)crystals at room temperature.Such broad photoluminescence originates from free excitons and self-trapped excitons.In addition,efficient second-harmonic generation(SHG)performance was observed in chiral perovskite single crystals with high circular polarization ratios and non-linear optical circular dichroism.This demonstrates that R/S-3BrMBA_(2)PbBr_(4)crystals can be used to detect and generate left-and righthanded circularly polarized light.Our study provides a new platform to develop high-performance chiroptical and spintronic devices.展开更多
Interfacial disorders in semiconductor quantum wells(QWs)determine material properties and device performance and have attracted great research efforts using different experimental methods.However,so far,there has bee...Interfacial disorders in semiconductor quantum wells(QWs)determine material properties and device performance and have attracted great research efforts using different experimental methods.However,so far,there has been no way to quantify the lateral length distribution of the interfacial disorders in QWs.Since photoluminescence(PL)is sensitive to exciton localization,the evolutions of PL energy and linewidth under external perpendicular magnetic fields have served as effective measurement methods for QW analysis;however,the evolution of PL intensity has not played a matching role.In this paper,we develop a theoretical model correlating the PL intensity with the interfacial disorders of type-I QWs under an external perpendicular magnetic field.We verify the model's rationality and functionality using In Ga(N)As/Ga As single QWs.In addition,we derive the Urbach energy and determine the lateral length distribution of interfacial disorders.The results show that the magnetic field-dependent PL intensity,as described by our model,serves as a valid probe for quantifying the interface flatness.The model also reveals that the mechanism of magnetic-field-induced intensity enhancement is a joint effect of interfacial disorder-induced exciton localization and the transfer of excitons from dark to bright states.These insights may benefit performance improvements of type-I QW materials and devices.展开更多
The properties and creation of optical centers in diamond are essential for applications in quantum technology.Here,we study the photoluminescence(PL)spectroscopy behavior at low temperatures of diamond subjected to e...The properties and creation of optical centers in diamond are essential for applications in quantum technology.Here,we study the photoluminescence(PL)spectroscopy behavior at low temperatures of diamond subjected to electron irradiation and annealing heat treatment.Through temperature variation testing,it was found that the NVcenter intensity of diamond with a nitrogen content of 150 ppm before treatment is insensitive to the experimental temperature,but significantly increases with decreasing temperature after treatment,showing sensitivity to temperature.In addition,the H3 center also shows an increasing trend with decreasing temperature.The results of annealing diamond with a nitrogen content of 730 ppm showed that even at a low temperature of 93 K,no NV^(-)centers were detected,but there were a large number of Ni-N related centers,especially NE8 centers.Our findings can promote a deeper understanding of the behavioral characteristics of HPHT-diamond optical centers in low-temperature environments.展开更多
Mn^(2+)-doped CsPbCl_(3)(Mn^(2+):CsPbCl_(3)) nanocrystals(NCs) have attracted considerable attention due to their unique strong and broad orange-red emission band,presenting promising applications in the field of phot...Mn^(2+)-doped CsPbCl_(3)(Mn^(2+):CsPbCl_(3)) nanocrystals(NCs) have attracted considerable attention due to their unique strong and broad orange-red emission band,presenting promising applications in the field of photoelectric devices.However,pristine Mn^(2+):CsPbCl_(3)NCs commonly suffer from low photoluminescence quantum yield(PL QY) and stability issues.Herein,we introduced europium ions(Eu^(3+))into Mn^(2+):CsPbCl_(3)NCs via the thermal injection synthesis method to obtain high performance Eu^(3+)and Mn^(2+)codoped CsPbCl_(3)(Eu^(3+)/Mn^(2+):CsPbCl_(3)) NCs.The maximum PL QY of the resulting Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs reaches up to 90.92%.It is found that the doping of Eu^(3+)ions significantly reduces the non-radiative recombination caused by high defect states,and improves the energy transfer efficiency from exciton to Mn^(2+),thereby boosting the PL performance.Moreover,doping Eu^(3+)ions notably improves the UV-light and water stability of Mn^(2+):CsPbCl_(3)NCs.We further demonstrate the application versatility of Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs in white light emitting diodes(WLEDs) and optical anticounterfeiting applications.This work provides a valuable perspective for the attainment of high performance Mn^(2+):CsPbCl_(3)NCs and lays a foundation for the codoping of other lanthanide ions to adjust the luminescence properties of Mn^(2+):CsPbCl_(3)NCs.展开更多
Large-scale synthesis of ZnO hexagonal pyramids was achieved by a simple thermal decomposition route of precursor at 240 oC in the presence of PEG400. The precursor was obtained by room-temperature solid-state grindin...Large-scale synthesis of ZnO hexagonal pyramids was achieved by a simple thermal decomposition route of precursor at 240 oC in the presence of PEG400. The precursor was obtained by room-temperature solid-state grinding reaction between Zn（CH3COO）2-2H2O and Na2CO3. Crystal structure and morphology of the products were analyzed and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and high-resolution transmission electron microscopy （HRTEM）. The results of further experiments show that PEG400 has an important role in the formation of ZnO hexagonal pyramids. Difference between the single and double hexagonal pyramid structure may come from the special thermal decomposition reaction. The photoluminescence （PL） spectra of ZnO hexagonal pyramids exhibit strong near-band-edge emission at about 386 nm and weak green emission at about 550 nm. The Raman-active vibration at about 435 cm-1 suggests that the ZnO hexagonal pyramids have high crystallinity.展开更多
Ce-doped ZnO microspheres were solvothermally prepared, and their microstructure, morphology, photoluminescence, and gas sensing were investigated by X-ray diffractometer, field emission scanning electron microscopy, ...Ce-doped ZnO microspheres were solvothermally prepared, and their microstructure, morphology, photoluminescence, and gas sensing were investigated by X-ray diffractometer, field emission scanning electron microscopy, transmission electron microscopy, fluorescence spectrometer and gas sensing analysis system. The results showed that the Ce-doped ZnO microspheres were composed of numerous nanorods with a diameter of 70 nm and a wurtzite structure. Ce-doping could cause a morphological transition from loose nanorods assembly to a tightly assembly in the microspheres. Compared with pure ZnO, the photoluminescence of the Ce-doped microspheres showed red-shifted UV emission and an enhanced blue emission. Particularly, the Ce-doped ZnO sensors exhibited much higher sensitivity and selectivity to ethanol than that of pure ZnO sensor at 320 °C. The ZnO microspheres doped with 6% Ce (mole fraction) exhibited the highest sensitivity (about 30) with rapid response (2 s) and recovery time (16 s) to 50×10?6 ethanol gas.展开更多
SnO2 nanowires with a diameter of 25nm are synthesized at 550~C by Au-Ag catalyst assisted thermal evapora- tion of SnO powders. The room-temperature photoluminescence spectra （PL） of the prepared nanowires are meas...SnO2 nanowires with a diameter of 25nm are synthesized at 550~C by Au-Ag catalyst assisted thermal evapora- tion of SnO powders. The room-temperature photoluminescence spectra （PL） of the prepared nanowires are measured. Among the four PL peaks,the peak of 418nm is newly observed. This peak is caused by the plane defects of the twinned crystal nanowires. The formation of SnO2 nanowires at low temperature is pursued on the basis of the VLS mechanism and application of the reaction source of SnO. We suggest that the chemical reactions of the low temperature and low concen- tration of the vaporized species are responsible for the thinner size of the SnO2 nanowires.展开更多
Neodymium is incorporated into single crystalline silicon on MEVVA (Metal Vapor Vacuum Arc) ion source.At room temperature,strong ultra violet and visible fluorescence are observed at the excitation wavelength of 220...Neodymium is incorporated into single crystalline silicon on MEVVA (Metal Vapor Vacuum Arc) ion source.At room temperature,strong ultra violet and visible fluorescence are observed at the excitation wavelength of 220nm.Luminescence intensity increases with the increase of ion fluence.XPS results manifest that Si-O,Nd-O,Si-Si and O-O bonds exist in the implanted layers.Luminescence mainly results from the radiation transition in the intra 4f shell of Nd 3+ ion.The defects' and damages' contribution to the luminescence is also presented.展开更多
Junctions are an important structure that allows charge separation in solar cells and photocatalysts. Here, we studied the charge transfer at an anatase/rutile TiO2 phase junction using time-resolved photoluminescence...Junctions are an important structure that allows charge separation in solar cells and photocatalysts. Here, we studied the charge transfer at an anatase/rutile TiO2 phase junction using time-resolved photoluminescence spectroscopy. Visible （-S00 nm） and near-infrared （NIR, -830 nm） emissions were monitored to give insight into the photoinduced charges of anatase and rutile in the junction, respectively, New fast photoluminescence decay components appeared in the visible emission of futile-phase dominated TiO2 and in the NIR emission of many mixed phase TiO2samples. The fast decays confirmed that the charge separation occurred at the phase junction. The visible emission intensity from the mixed phase TiO2 increased, revealing that charge transfer from rutile to anatase was the main pathway. The charge separation slowed the microsecond time scale photolumines- cence decay rate for charge carriers in both anatase and rutile. However, the millisecond decay of the charge carriers in anatase TiO2 was accelerated, while there was almost no change in the charge carrier dynamics of rutile TiO2. Thus, charge separation at the anatase/rutile phase junction caused an increase in the charge carrier concentration on a microsecond time scale, because of slower electron-hole recombination. The enhanced photocatalytic activity previously observed at ana- tase/rutile phase junctions is likely caused by the improved charge carrier dynamics we report here. These findings may contribute to the development of improved photocatalytic materials.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
The transitions of E0 ,E0 ＋A0, and E＋ in dilute GaAs（1-x） Nx alloys with x = 0.10% ,0.22% ,0.36% ,and 0.62% are observed by micro-photoluminescence. Resonant Raman scattering results further confirm that they are ...The transitions of E0 ,E0 ＋A0, and E＋ in dilute GaAs（1-x） Nx alloys with x = 0.10% ,0.22% ,0.36% ,and 0.62% are observed by micro-photoluminescence. Resonant Raman scattering results further confirm that they are from the intrinsic emissions in the studied dilute GaAsN alloys rather than some localized exciton emissions in the GaAsN alloys. The results show that the nitrogen-induced E E＋ and E0 ＋ A0 transitions in GaAsN alloys intersect at a nitrogen content of about 0.16%. It is demonstrated that a small amount of isoelectronic doping combined with micro-photoluminescence allows direct observation of above band gap transitions that are not usually accessible in photoluminescence.展开更多
Synthesis of amorphous SiCO nanowires was carried out by means of direct current are discharge. Free-standing SiCO nanowires were deposited on the surface of a graphite crucible without any catalyst and template. The ...Synthesis of amorphous SiCO nanowires was carried out by means of direct current are discharge. Free-standing SiCO nanowires were deposited on the surface of a graphite crucible without any catalyst and template. The SiCO nanowires were analyzed by XRD, SEM, TEM, XPS, and FTIR. The SiCO nanowires were typically 20-100 gm in length and 10-100 nm in diameter as measured by SEM and TEM. The XPS and FTIR spectroscopy analysis confirmed that the Si atoms share bonds with O and C atoms in mixed SiCO units. The PL spectrum of the SiCO nanowires showed strong and stable white emissions at 454 and 540 nm. A plasma-assisted vapor-solid growth mechanism is proposed to be responsible for the formation of the SiCO nanowires.展开更多
Erbium （Er） doped in nanocrystalline Si （nc-Si：Er） surrounded by SiO2 is investigated by selectivelyexcited photoluminescence（PL） technique. Optical transitions come from nc-Si （peak located at 1.39 eV, denote...Erbium （Er） doped in nanocrystalline Si （nc-Si：Er） surrounded by SiO2 is investigated by selectivelyexcited photoluminescence（PL） technique. Optical transitions come from nc-Si （peak located at 1.39 eV, denoted as Enc-Si） and Er ions （peak located at 0. 81 eV, denoted as EEr） are measured when nc-Si：Er is excited by 1. 519 eV or higher excitation photon energy（Eex）. Although the Eex of 1.42 eV exceeds the peak energies of Enc-Si and EEr the Enc-Si and EE, emissions are unobserved. A resonant enhancement of the EEr emission is observed in nc-Si：Er. While the PL peak intensitiy of the Enc-Si transition is quenched under this Eex. The resonant-enhanced effect in nc-Si ：Er indicates that the energy transfer process of carriers from nc-Si to nearby Er ions is enhanced by resonant excitation.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
基金the Ministry of Education and Science of the Russian Federation (state assignment No. FSEG-2023-0016) for financial support of optical studiesfinancially supported by FSRM 2023-0007 project provided by the Ministry of Education and Science of the Russian Federation.
文摘InAsN nanowires on InAs stems were obtained using plasma-assisted molecular beam epitaxy on a SiOx/Si(111)sub-strate.Also,heterostructured InAs/InAsN and InAsN/InP nanowires were grown in the core/shell geometry.In the low-temperature photoluminescence spectra of the grown structures,spectral features are observed that correspond to the polytypic structure of nanowires with a predominance of the wurtzite phase and parasitic islands of the sphalerite phase.It was shown that the interband photoluminescence spectral features of InAsN nanowires experience a red shift relative to the pristine InAs nanowires.The incorporation of nitrogen reduces the bandgap by splitting the conduction band into two subbands.The position of the spectral features in the photoluminescence spectra confirms the formation of a nitride solid solution with a poly-typic hexagonal structure,having a concentration of nitrogen atoms of up to 0.7%.Additional passivation of the nanowire surface with InP leads to a decrease in the intensity of nonradiative recombination and an improvement in the photoluminescent response of the nanowires,which makes it possible to detect photoluminescence emission at room temperature.Thus,by changing the composition and morphology of nanowires,it is possible to control their electronic structure,which allows varying the operating range of detectors and mid-IR radiation sources based on them.
基金supported by the National Natural Science Foundation of China(51701091,12004148,12104199,12204216)the Natural Science Foundation of Shandong Province(ZR2021QA057)+1 种基金the Shandong Province Science and Technology Small and Medium Sized Enterprise Innovation Ability Enhancement Project(2023TSGC0352)the Innovation Team of Higher Educational Science and Technology Program of Shandong Province(2019KJA025)。
文摘Ultraviolet upconversion photoluminescence materials have great potential in various fields,but the improvement of the upconversion efficiency is challenging.Codoping of Li^(+)is considered as an effective strategy and widely used to improve the photoluminescence properties of phosphors.In this paper,Li^(+)is introduced into a Y_(7)O_(6)F_(9):Pr^(3+),Gd^(3+)system.The effect of Li^(+)codoping on the phase purity,crystal structure,micro structure,downshifting and upconversion photo luminescence as well as the decay dynamic of the phosphors was studied.It is revealed that the overall photoluminescence efficiency and the energy transfer efficiency from pr^(3+)to Gd^(3+)are greatly promoted.The downshifting and upconversion photoluminescence increase by 2.58 and 10 times as 6 mol%of Li^(+)is codoped.The photo luminescence decay dynamic study shows that the ^(3)P_(0)state decays slower in the Li^(+)-containing phosphor than the Li^(+)-free one.The improvement of the photoluminescence properties is due to the increase of the crystallinity and the reduce of the quenching center.
文摘Nano phosphors of 2%Dy^(3+)(wt%)doped La_(2)MgTiO_(6) and monovalent/divalent/trivalent co-doped La_(1.98)Dy_(0.02)MgTiO_(6):x%A^(y+)(A^(y+):Li+,Ba^(2+),Sr^(2+),Bi^(3+),and Sm^(3+);0≤x≤2 wt%)were synthesized by combustion method.From the XRD data,it is deduced that an increase in the valency of co-dopant increases the crystallinity of the double perovskite orthorhombic nanocrystal structure.With an increase in co-dopant size,an elevation in optical bandgap is visible with the highest bandgap of 3.835 eV for Bi^(3+).The photo-absorption is monotonically broadened for Sr^(2+),Sm^(3+),and Li+around 200-450 nm.Under351 nm,Dy^(3+)triggered lattice shows major characteristic emission peaks at 480 nm(^(4)F_(9/2)→^(6)H_(15/2)),574 nm(^(4)F_(9/2)→^(6)H_(13/2)),and 670 nm(^(4)F_(9/2)→^(6)H_(11/2)).leading to near white light emission with CIE coordinates(0.341,0.376).Upon co-doping,the PL intensity is significantly increased with maximum emission for trivalent Sm^(3+),followed by divalent Sr^(2+)and monovalent Li+respectively.With increasing excitation wavelength,Sr^(2+)shows a dominated output and it is found that divalent Sr^(2+)is a potential codopant that could enhance luminescence intensity up to 6 times with a Sr^(2+)→Dy^(3+)energy transfer efficiency of 86%.It is specified that the CIE coordinates of Li+co-doped samples show ideal white emission with color coordinates(0.333,0.336).The concluding outcomes signify the noblest rare earth Sm^(3+)co-doping and thus Sm^(3+)→Dy^(3+)energy transfer mechanism is discussed in detail.
基金financial supported from the Thailand Research Fund,Office of the Higher Education Commission(Grant number MRG6280220)。
文摘In this research study,magnesium-aluminum(Mg-Al)bimetallic oxide powders are synthesized via the sol-gel auto combustion method using diethanolamine(DEA)as the fuel.In order to subsequently determine the influence of calcination temperatures upon the structure,chemical bonding,morphology,optical properties,and fluorescence properties of the as-synthesized and calcined Mg-Al bimetallic oxide powders,the researcher employed X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),transmission electron microscopy(TEM),UV–visible diffuse reflectance spectroscopy(UV-DRS),and photoluminescence spectroscopy(PL),respectively.It was apparent on the basis of the XRD and FT-IR analyses that those powders undergoing calcination at temperatures of 500℃,700℃,and 900℃contained the major phase magnesium aluminate(Mg Al_(2)O_(4))spinel with trace magnesium oxide(Mg O)and hydrotalcite(Mg_(6)Al_(2)(CO_(3))(OH)_(16)).When the calcination temperature rose to 1100℃,this resulted in a single phase MgAl_(2)O_(4)while MgO and(Mg_(6)Al_(2)(CO_(3))(OH)_(16))were no longer observed.UV-DRS analysis revealed that in optimized conditions,calcination resulted in better sample absorption and reflection levels when compared to the ultraviolet,visible,and infrared spectra observed in the case of the as-synthesized sample.The bandgap energy(E_(g))for calcined samples was in the range of 2.65 e V to 5.85 e V,in contrast to the value of 4.10 e V for the as-synthesized sample.Analysis of photoluminescence showed that for the as-synthesized samples and those calcined at low temperatures,visible light was emitted only in the violet,blue,and green regions with low intensity,while for samples calcined at higher temperatures,the emissions showed greater intensity and extended to the yellow and orange regions.Multiple defect centers were found in the bandgap which can explain these findings.
基金Project supported by the National Key Research and Development Program of China(2024YFE0206100)the National Natural Science Foundation of China(T2325015,U21A2068,12174151)。
文摘Achieving high-efficiency photoluminescence in trivalent lanthanides(Ln^(3+))requires precise crystalfield perturbation to overcome parity-forbidden 4f-transitions and suppress nonradiative decay.However,realizing such control remains challenging,even in well-optimized Ln^(3+) -doped nanocrystals.Here,by exploiting the atomically precise structure of metal nanoclusters,we demonstrate symmetry engineering in the Eu_(2)Ti_(4) nanoclusters through stepwise ligand substitution(BA/Phen→FBA/Phen→FBA/Bpy.BA:benzoicacid;Phen:1,10-phenanthroline;FBA:p-fluorobenzoicacid;Bpy:2,2'-bipyridine).The incorporation of FBA effectively suppresses nonradiative relaxation,while the flexible Bpy ligand induces symmetry reduction from D_(2d) to C_(2v) through coordination modulation,yielding a high photoluminescence quantum yield(PLQY)of 91.2%in the Ln^(3+) cluster systems.The transient-absorption,Judd-Ofelt theory,crystal-field analysis,and temperature-dependent photophysical studies elucidated the underlying modulation mechanisms.Furthermore,these clusters exhibit promising potential for optoelectronic applications,offering a new design strategy for high-performance luminescent materials.
基金the CAS Project for Young Scientists in Basic Research(No.YSBR-042)the National Natural Science Foundation of China(Nos.12125508,11935020)+2 种基金Program of Shanghai Academic/Technology Research Leader(No.21XD1404100)the Shanghai Pilot Program for Basic Research-Chinese Academy of SciencesShanghai Branch(No.JCYJ-SHFY-2021-010).
文摘There is a growing interest in the rapid assessment of terahertz(THz)spectroscopy owing to its promising application pros-pects in nondestructive testing,security screening,and communication.In this study,we introduce a swift characterization method for THz spectroscopy that utilizes a THz-to-optical conversion system in a warm atomic vapor cell.By subtracting the photoluminescence(PL)spectra of cesium atoms with the THz field from those without the THz field,we obtained differential PL spectra that effectively characterized the 0.548 THz field.The differential PL spectra of Rydberg atoms offer the opportunity to quantify the THz field’s intensity and frequency,potentially paving the way for the development of THz spectroscopy based on warm atomic vapor cells.
基金supported by Natural Science Foundation of Jiangsu Province,Major Project(BK20222007).
文摘Two-dimensional(2D)chiral halide perovskites(CHPs)have attracted broad interest due to their distinct spin-dependent properties and promising applications in chiroptics and spintronics.Here,we report a new type of 2D CHP single crystals,namely R/S-3BrMBA_(2)PbBr_(4).The chirality of the as-prepared samples is confirmed by exploiting circular dichroism spectroscopy,indicating a successful chirality transfer from chiral organic cations to their inorganic perovskite sublattices.Furthermore,we observed bright photoluminescence spanning from 380 to 750 nm in R/S-3BrMBA_(2)PbBr_(4)crystals at room temperature.Such broad photoluminescence originates from free excitons and self-trapped excitons.In addition,efficient second-harmonic generation(SHG)performance was observed in chiral perovskite single crystals with high circular polarization ratios and non-linear optical circular dichroism.This demonstrates that R/S-3BrMBA_(2)PbBr_(4)crystals can be used to detect and generate left-and righthanded circularly polarized light.Our study provides a new platform to develop high-performance chiroptical and spintronic devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.12227901,12393830,and 12274429)the STCSM(Grant No.22QA1410600)。
文摘Interfacial disorders in semiconductor quantum wells(QWs)determine material properties and device performance and have attracted great research efforts using different experimental methods.However,so far,there has been no way to quantify the lateral length distribution of the interfacial disorders in QWs.Since photoluminescence(PL)is sensitive to exciton localization,the evolutions of PL energy and linewidth under external perpendicular magnetic fields have served as effective measurement methods for QW analysis;however,the evolution of PL intensity has not played a matching role.In this paper,we develop a theoretical model correlating the PL intensity with the interfacial disorders of type-I QWs under an external perpendicular magnetic field.We verify the model's rationality and functionality using In Ga(N)As/Ga As single QWs.In addition,we derive the Urbach energy and determine the lateral length distribution of interfacial disorders.The results show that the magnetic field-dependent PL intensity,as described by our model,serves as a valid probe for quantifying the interface flatness.The model also reveals that the mechanism of magnetic-field-induced intensity enhancement is a joint effect of interfacial disorder-induced exciton localization and the transfer of excitons from dark to bright states.These insights may benefit performance improvements of type-I QW materials and devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.12274373,12274372,and 12204259)the Natural Science Foundation of Henan Province(Grant No.242300421155)+2 种基金the Key Research Projects of Higher Education Institutions in Henan Province(Grant No.25A140008)the Science and Technology Base and Talent Project of Guangxi,China(Grant No.AD21220154)the Central Plains Science and Technology Innovation Youth Top Notch Talents.
文摘The properties and creation of optical centers in diamond are essential for applications in quantum technology.Here,we study the photoluminescence(PL)spectroscopy behavior at low temperatures of diamond subjected to electron irradiation and annealing heat treatment.Through temperature variation testing,it was found that the NVcenter intensity of diamond with a nitrogen content of 150 ppm before treatment is insensitive to the experimental temperature,but significantly increases with decreasing temperature after treatment,showing sensitivity to temperature.In addition,the H3 center also shows an increasing trend with decreasing temperature.The results of annealing diamond with a nitrogen content of 730 ppm showed that even at a low temperature of 93 K,no NV^(-)centers were detected,but there were a large number of Ni-N related centers,especially NE8 centers.Our findings can promote a deeper understanding of the behavioral characteristics of HPHT-diamond optical centers in low-temperature environments.
基金Project supported by the National Natural Science Foundation of China (12174075)the Scientific and Technological Bases and Talents of Guangxi (Guike AD21220016)+1 种基金Guangxi Science and Technology Major Project(AA23073018)the special fund for Guangxi Bagui Scholars。
文摘Mn^(2+)-doped CsPbCl_(3)(Mn^(2+):CsPbCl_(3)) nanocrystals(NCs) have attracted considerable attention due to their unique strong and broad orange-red emission band,presenting promising applications in the field of photoelectric devices.However,pristine Mn^(2+):CsPbCl_(3)NCs commonly suffer from low photoluminescence quantum yield(PL QY) and stability issues.Herein,we introduced europium ions(Eu^(3+))into Mn^(2+):CsPbCl_(3)NCs via the thermal injection synthesis method to obtain high performance Eu^(3+)and Mn^(2+)codoped CsPbCl_(3)(Eu^(3+)/Mn^(2+):CsPbCl_(3)) NCs.The maximum PL QY of the resulting Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs reaches up to 90.92%.It is found that the doping of Eu^(3+)ions significantly reduces the non-radiative recombination caused by high defect states,and improves the energy transfer efficiency from exciton to Mn^(2+),thereby boosting the PL performance.Moreover,doping Eu^(3+)ions notably improves the UV-light and water stability of Mn^(2+):CsPbCl_(3)NCs.We further demonstrate the application versatility of Eu^(3+)/Mn^(2+):CsPbCl_(3)NCs in white light emitting diodes(WLEDs) and optical anticounterfeiting applications.This work provides a valuable perspective for the attainment of high performance Mn^(2+):CsPbCl_(3)NCs and lays a foundation for the codoping of other lanthanide ions to adjust the luminescence properties of Mn^(2+):CsPbCl_(3)NCs.
基金Project (BK2009379) supported by the Natural Science Foundation of Jiangsu Province, ChinaProject (1006-56XNA12069) supported by the Nanjing University of Aeronautics and Astronautics Research Funding, China+3 种基金Projects (51172108, 91023020) supported by the National Natural Science Foundation of ChinaProject (IRT0968) supported by the Program for Changjiang Scholars and Innovative Research Team in University, ChinaProject (NCET-10-0070) supported by the Program for New Century Excellent Talents in University, ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions, China
文摘Large-scale synthesis of ZnO hexagonal pyramids was achieved by a simple thermal decomposition route of precursor at 240 oC in the presence of PEG400. The precursor was obtained by room-temperature solid-state grinding reaction between Zn（CH3COO）2-2H2O and Na2CO3. Crystal structure and morphology of the products were analyzed and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and high-resolution transmission electron microscopy （HRTEM）. The results of further experiments show that PEG400 has an important role in the formation of ZnO hexagonal pyramids. Difference between the single and double hexagonal pyramid structure may come from the special thermal decomposition reaction. The photoluminescence （PL） spectra of ZnO hexagonal pyramids exhibit strong near-band-edge emission at about 386 nm and weak green emission at about 550 nm. The Raman-active vibration at about 435 cm-1 suggests that the ZnO hexagonal pyramids have high crystallinity.
基金Project(61079010)supported by the National Natural Science Foundation of China and the Civil Aviation Administration of ChinaProject(3122013P001)supported by the Significant Pre-research Funds of Civil Aviation University of ChinaProject(MHRD20140209)supported by the Science and Technology Innovation Guide Funds of Civil Aviation Administration of China
文摘Ce-doped ZnO microspheres were solvothermally prepared, and their microstructure, morphology, photoluminescence, and gas sensing were investigated by X-ray diffractometer, field emission scanning electron microscopy, transmission electron microscopy, fluorescence spectrometer and gas sensing analysis system. The results showed that the Ce-doped ZnO microspheres were composed of numerous nanorods with a diameter of 70 nm and a wurtzite structure. Ce-doping could cause a morphological transition from loose nanorods assembly to a tightly assembly in the microspheres. Compared with pure ZnO, the photoluminescence of the Ce-doped microspheres showed red-shifted UV emission and an enhanced blue emission. Particularly, the Ce-doped ZnO sensors exhibited much higher sensitivity and selectivity to ethanol than that of pure ZnO sensor at 320 °C. The ZnO microspheres doped with 6% Ce (mole fraction) exhibited the highest sensitivity (about 30) with rapid response (2 s) and recovery time (16 s) to 50×10?6 ethanol gas.
文摘SnO2 nanowires with a diameter of 25nm are synthesized at 550~C by Au-Ag catalyst assisted thermal evapora- tion of SnO powders. The room-temperature photoluminescence spectra （PL） of the prepared nanowires are measured. Among the four PL peaks,the peak of 418nm is newly observed. This peak is caused by the plane defects of the twinned crystal nanowires. The formation of SnO2 nanowires at low temperature is pursued on the basis of the VLS mechanism and application of the reaction source of SnO. We suggest that the chemical reactions of the low temperature and low concen- tration of the vaporized species are responsible for the thinner size of the SnO2 nanowires.
文摘Neodymium is incorporated into single crystalline silicon on MEVVA (Metal Vapor Vacuum Arc) ion source.At room temperature,strong ultra violet and visible fluorescence are observed at the excitation wavelength of 220nm.Luminescence intensity increases with the increase of ion fluence.XPS results manifest that Si-O,Nd-O,Si-Si and O-O bonds exist in the implanted layers.Luminescence mainly results from the radiation transition in the intra 4f shell of Nd 3+ ion.The defects' and damages' contribution to the luminescence is also presented.
基金supported by the National Natural Science Foundation of China (21203185, 21373209)the National Basic Research Program of China (2014CB239400)
文摘Junctions are an important structure that allows charge separation in solar cells and photocatalysts. Here, we studied the charge transfer at an anatase/rutile TiO2 phase junction using time-resolved photoluminescence spectroscopy. Visible （-S00 nm） and near-infrared （NIR, -830 nm） emissions were monitored to give insight into the photoinduced charges of anatase and rutile in the junction, respectively, New fast photoluminescence decay components appeared in the visible emission of futile-phase dominated TiO2 and in the NIR emission of many mixed phase TiO2samples. The fast decays confirmed that the charge separation occurred at the phase junction. The visible emission intensity from the mixed phase TiO2 increased, revealing that charge transfer from rutile to anatase was the main pathway. The charge separation slowed the microsecond time scale photolumines- cence decay rate for charge carriers in both anatase and rutile. However, the millisecond decay of the charge carriers in anatase TiO2 was accelerated, while there was almost no change in the charge carrier dynamics of rutile TiO2. Thus, charge separation at the anatase/rutile phase junction caused an increase in the charge carrier concentration on a microsecond time scale, because of slower electron-hole recombination. The enhanced photocatalytic activity previously observed at ana- tase/rutile phase junctions is likely caused by the improved charge carrier dynamics we report here. These findings may contribute to the development of improved photocatalytic materials.
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.
文摘The transitions of E0 ,E0 ＋A0, and E＋ in dilute GaAs（1-x） Nx alloys with x = 0.10% ,0.22% ,0.36% ,and 0.62% are observed by micro-photoluminescence. Resonant Raman scattering results further confirm that they are from the intrinsic emissions in the studied dilute GaAsN alloys rather than some localized exciton emissions in the GaAsN alloys. The results show that the nitrogen-induced E E＋ and E0 ＋ A0 transitions in GaAsN alloys intersect at a nitrogen content of about 0.16%. It is demonstrated that a small amount of isoelectronic doping combined with micro-photoluminescence allows direct observation of above band gap transitions that are not usually accessible in photoluminescence.
基金This work was supported by National Natural Science Foundation of China （No.61474009 and No.11304020） and the Educational Commission of Liaoning Province of China （No.L2014448）.
文摘Synthesis of amorphous SiCO nanowires was carried out by means of direct current are discharge. Free-standing SiCO nanowires were deposited on the surface of a graphite crucible without any catalyst and template. The SiCO nanowires were analyzed by XRD, SEM, TEM, XPS, and FTIR. The SiCO nanowires were typically 20-100 gm in length and 10-100 nm in diameter as measured by SEM and TEM. The XPS and FTIR spectroscopy analysis confirmed that the Si atoms share bonds with O and C atoms in mixed SiCO units. The PL spectrum of the SiCO nanowires showed strong and stable white emissions at 454 and 540 nm. A plasma-assisted vapor-solid growth mechanism is proposed to be responsible for the formation of the SiCO nanowires.
基金Supported by the Natural Science Foundation for Key Program of Jiangsu Higher Education Institu-tions of China(08KJA510002)the″Six Top Talents″Project of Jiangsu Province+2 种基金the Application Research Program of Nantong,China(K2007016,K2008024)the Creative Talents Foundation of Nantong Universitythe Natural Science Foundation(07Z122)of Nantong University~~
文摘Erbium （Er） doped in nanocrystalline Si （nc-Si：Er） surrounded by SiO2 is investigated by selectivelyexcited photoluminescence（PL） technique. Optical transitions come from nc-Si （peak located at 1.39 eV, denoted as Enc-Si） and Er ions （peak located at 0. 81 eV, denoted as EEr） are measured when nc-Si：Er is excited by 1. 519 eV or higher excitation photon energy（Eex）. Although the Eex of 1.42 eV exceeds the peak energies of Enc-Si and EEr the Enc-Si and EE, emissions are unobserved. A resonant enhancement of the EEr emission is observed in nc-Si：Er. While the PL peak intensitiy of the Enc-Si transition is quenched under this Eex. The resonant-enhanced effect in nc-Si ：Er indicates that the energy transfer process of carriers from nc-Si to nearby Er ions is enhanced by resonant excitation.
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.
