Mn^(2+)doping has been adopted as an efficient approach to regulating the luminescence properties of halide perovskite nano-crystals(NCs).However,it is still difficult to understand the interplay of Mn^(2+)luminescenc...Mn^(2+)doping has been adopted as an efficient approach to regulating the luminescence properties of halide perovskite nano-crystals(NCs).However,it is still difficult to understand the interplay of Mn^(2+)luminescence and the matrix self-trapped exciton(STE)emission therein.In this study,Mn^(2+)-doped CsCdCl_(3) NCs are prepared by hot injection,in which CsCdCl_(3) is selected because of its unique crystal structure suitable for STE emission.The blue emission at 441 nm of undoped CsCdCl_(3) NCs originates from the defect states in the NCs.Mn^(2+)doping promotes lattice distortion of CsCdCl_(3) and generates bright orange-red light emission at 656 nm.The en-ergy transfer from the STEs of CsCdCl_(3) to the excited levels of the Mn^(2+)ion is confirmed to be a significant factor in achieving efficient luminescence in CsCdCl_(3):Mn^(2+)NCs.This work highlights the crucial role of energy transfer from STEs to Mn^(2+)dopants in Mn^(2+)-doped halide NCs and lays the groundwork for modifying the luminescence of other metal halide perovskite NCs.展开更多
Ternary metal halides based on Cu(I)and Ag(I)have attracted intensive attention in optoelectronic applications due to their excellent luminescent properties,low toxicity,and robust stability.While the self-trapped exc...Ternary metal halides based on Cu(I)and Ag(I)have attracted intensive attention in optoelectronic applications due to their excellent luminescent properties,low toxicity,and robust stability.While the self-trapped excitons(STEs)emission mechanisms of Cu(I)halides are well understood,the STEs in Ag(I)halides remain less thoroughly explored.This study explores the STE emission efficiency within the A_(2)AgX_(3)(A=Rb,Cs;X=Cl,Br,I)system by identifying three distinct STE states in each material and calculating their configuration coordinate diagrams.We find that the STE emission efficiency in this system is mainly determined by STE stability and influenced by self-trapping and quenching barriers.Moreover,we investigate the impact of structural compactness on emission efficiency and find that the excessive electron–phonon coupling in this system can be reduced by increasing the structural compactness.The atomic packing factor is identified as a low-cost and effective descriptor for predicting STE emission efficiency in both Cs_(2)AgX_(3) and Rb_(2)AgX_(3) systems.These findings can deepen our understanding of STE behavior in metal halide materials and offer valuable insights for the design of efficient STE luminescent materials.The datasets presented in this paper are openly available in Science Data Bank at https://doi.org/10.57760/sciencedb.12094.展开更多
Light-emitting diodes based on lead halide perovskite have attracted great attention due to their outstanding performance.However,their application is plagued by the toxicity of Pb and the poor stability.Herein novel ...Light-emitting diodes based on lead halide perovskite have attracted great attention due to their outstanding performance.However,their application is plagued by the toxicity of Pb and the poor stability.Herein novel copper-based all inorganic perovskite CsCu2I3 with much enhanced stability has been reported with a potential photoluminescence quantum yield(PLQY)over 20%and self-trapped excitons(STE).By taking advantage of its extraordinary thermal stability,we successfully fabricate high-quality CsCu2I3 film through direct vacuum-based deposition(VBD)of CsCu2I3 powder.The resulting film shows almost the same PLQY with the synthesized powder,as well as excellent uniformity and stability.The perovskite light-emitting diodes(Pe-LED)based on the evaporated CsCu2I3 emitting layer achieve a luminescence of 10 cd/m2 and an external quantum efficiency(EQE)of 0.02%.To the best of our knowledge,this is the first CsCu2I3 Pe-LED fabricated by VBD with STE property,which offers a new avenue for lead-free Pe-LED.展开更多
Zero-dimensional metal halides are of unique structures and tunable photoluminescence properties,showing great potential applications such as light-emitting diodes(LEDs)and sensing.Herein,we successfully synthesized C...Zero-dimensional metal halides are of unique structures and tunable photoluminescence properties,showing great potential applications such as light-emitting diodes(LEDs)and sensing.Herein,we successfully synthesized Cu^(+)doped(MA)_(2)ZnCl_(4)metal halides by a slow evaporation solvent method.The introduction of Cu^(+)results in sky-blue self-trapped exciton emission in(MA)_(2)ZnCl_(4) at 486 nm at room temperature,and a photoluminescence quantum yield is as high as 54.9%.Interestingly,at low temperatures,Cu^(+)-doped(MA)_(2)ZnCl_(4) exhibits two emission peaks located at 482 and 605 nm,respectively.This temperaturedependent dual emission indicates two excited state structures that exist on the triplet excited-state potential energy surface.In addition,the temperature sensor we fitted has good performance(Sr=1.65%·K^(−1)),which is the first attempt in Cu^(+) doped Znbased metal halides.Our work enriches the family of sky-blue metal halides and provides a promising strategy for building skyblue LEDs.展开更多
The vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),as a newly-emerging lead-free perovskite system,has attracted great research interest due to its excellent stability and direct band gap.However,the poor ...The vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),as a newly-emerging lead-free perovskite system,has attracted great research interest due to its excellent stability and direct band gap.However,the poor luminescence performance limits its application in light-emitting diodes(LEDs)and other fields.Herein,for the first time,an Ag^(+)ion doping strategy was proposed to greatly improve the emission performance of Cs_(4)CdBi_(2)Cl_(12) synthesized by hydrothermal method.Density functional theory calculations combined with experimental results evidence that the weak orange emission from Cs_(4)CdBi_(2)Cl_(12) is attributed to the phonon scattering and energy level crossing due to the large lattice distortion under excited states.Fortunately,Ag^(+)ion doping breaks the intrinsic crystal field environment of Cs_(4)CdBi_(2)Cl_(12),suppresses the crossover between ground and excited states,and reduces the energy loss in the form of nonradiative recombination.At a critical doping amount of 0.8%,the emission intensity of Cs_(4)CdBi_(2)Cl_(12):Ag^(+)reaches the maximum,about eight times that of the pristine sample.Moreover,the doped Cs_(4)CdBi_(2)Cl_(12) still maintains excellent stability against heat,ultraviolet irradiation,and environmental oxygen/moisture.The above advantages make it possible for this material to be used as solid-state phosphors for white LEDs applications,and the Commission International de I’Eclairage color coordinates of(0.31,0.34)and high color rendering index of 90.6 were achieved.More importantly,the white LED demonstrates remarkable operation stability in air ambient,showing almost no emission decay after a long working time for 48 h.We believe that this study puts forward an effective ion-doping strategy for emission enhancement of vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),highlighting its great potential as efficient emitter compatible for practical applications.展开更多
Self-trapped excitons(STEs)emission from halide perovskites with strong exciton-phonon coupling has attracted considerable attention due to the widespread application in optoelectronic devices.Nevertheless,the in-dept...Self-trapped excitons(STEs)emission from halide perovskites with strong exciton-phonon coupling has attracted considerable attention due to the widespread application in optoelectronic devices.Nevertheless,the in-depth understanding of the relationship between exciton-phonon coupling and luminescence intensity remains incomplete.Herein,a doping-enhanced exciton-phonon coupling effect is observed in Cs_(3)Cu_(2)I_(5)nanocrystals(NCs),which leads to a remarkable increasement of their STEs emission efficiency.Mechanism study shows that the hetero-valent substitution of Cu+with alkaline-earth metal ions(AE^(2+))causes a greater degree of Jahn-Teller distortion between the ground state and excited state structures of[Cu_(2)I_(5)]_(3)-clusters as evidenced by our spectral analysis and first-principles calculations.As a consequence,an X-ray detector based on these Cs_(3)Cu_(2)I_(5):AE NCs delivers an X-ray imaging resolution of up to 10 lp·mm^(-1) and a low detection limit of 0.37μGyair·s^(-1),disclosing the potential of doping-enhanced exciton-phonon coupling effect in improving STEs-emission and practical application for X-ray imaging.展开更多
Sb-based organic–inorganic hybrid metal halides(OIHMHs)with[SbCl5]2−units have been widely reported due to high photoluminescence quantum yield(PLQY)and occasional multiple self-trapped exciton(STE)emission bands mai...Sb-based organic–inorganic hybrid metal halides(OIHMHs)with[SbCl5]2−units have been widely reported due to high photoluminescence quantum yield(PLQY)and occasional multiple self-trapped exciton(STE)emission bands mainly out of singlet and triplet states,and their multi-band emission is important in white light-emitting diode(WLED).However,not all these OIHMH compounds can produce both emissions out of singlet STE and triplet STE at room temperature simultaneously.It is crucial to consider how the singlet STE generates and retains to emit light at room temperature for this material’s design and application.Herein,a strategy is proposed that can significantly lift Sb halide PLQY by synthesizing two Sb-based OIHMHs using organic amine cations of different-sized and-quantity,which modulate the distance of neighboring emission centers.Therein,the occurrence of singlet STE emission is found to be closely related to the distance of[SbCl_(5)]^(2)−units and local unit distortion in the lattice.The larger distance can produce smaller local distortions,favoring the formation of the singlet STE emission band at higher energy.This is the first work to reveal the relationship between the local structure and the origin of the singlet STE emission band,providing new insights into the modulation of the Sb-based OIHMH’s emission.展开更多
With strong electron-phonon coupling,the self-trapped excitons are usually formed in materials,which leads to the local lattice distortion and localized excitons.The self-trapping strongly depends on the dimensionalit...With strong electron-phonon coupling,the self-trapped excitons are usually formed in materials,which leads to the local lattice distortion and localized excitons.The self-trapping strongly depends on the dimensionality of the materials.In the three dimensional case,there is a potential barrier for self-trapping,whereas no such barrier is present for quasi-one-dimensional systems.Two-dimensional(2D)systems are marginal cases with a much lower potential barrier or nonex istent potential barrier for the self-trapping,leading to the easier formation of self-trapped states.Self-trapped excitons emission exhibits a broadband emission with a large Stokes shift below the bandgap.2D perovskites are a class of layered structure material with unique optical properties and would find potential promising optoelectronic.In particular,self-trapped excitons are present in 2D per-ovskites and can significantly influence the optical and electrical properties of 2D perovskites due to the soft characteristic and strong electron-phonon interaction.Here,we summarized the luminescence characteristics,origins,and characterizations of self-trapped excitons in 2D perovskites and finally gave an introduction to their applications in optoelectronics.展开更多
Perovskite variants have attracted wide interest because of the lead-free nature and strong self-trapped exciton (STE) emission. Divalent Sn(II) in CsSnX3 perovskites is easily oxidized to tetravalent Sn(IV), and the ...Perovskite variants have attracted wide interest because of the lead-free nature and strong self-trapped exciton (STE) emission. Divalent Sn(II) in CsSnX3 perovskites is easily oxidized to tetravalent Sn(IV), and the resulted Cs2SnCl6 vacancy-ordered perovskite variant exhibits poor photoluminescence property although it has a direct band gap. Controllable doping is an effective strategy to regulate the optical properties of Cs2SnX6. Herein, combining the first principles calculation and spectral analysis, we attempted to understand the luminescence mechanism of Te4+-doped Cs2SnCl6 lead-free perovskite variants. The chemical potential and defect formation energy are calculated to confirm theoretically the feasible substitutability of tetravalent Te4+ ions in Cs2SnCl6 lattices for the Sn-site. Through analysis of the absorption, emission/excitation, and time-resolved photoluminescence (PL) spectroscopy, the intense green-yellow emission in Te4+:Cs2SnCl6 was considered to originate from the triplet Te(IV) ion 3P1→1S0 STE recombination. Temperature-dependent PL spectra demonstrated the strong electron-phonon coupling that inducing an evident lattice distortion to produce STEs. We further calculated the electronic band structure and molecular orbital levels to reveal the underlying photophysical process. These results will shed light on the doping modulated luminescence properties in stable lead-free Cs2MX6 vacancy-ordered perovskite variants and be helpful to understand the optical properties and physical processes of doped perovskite variants.展开更多
Two-dimensional(2D)perovskites exhibit broadband emission due to strong exciton–phonon coupling-induced self-trapped excitons and thus would find important applications in the field of white-light emitting devices.Ho...Two-dimensional(2D)perovskites exhibit broadband emission due to strong exciton–phonon coupling-induced self-trapped excitons and thus would find important applications in the field of white-light emitting devices.However,the available identifying methods for self-trapped excitons are currently rather limited and complex.Here,we identify the existence of self-trapped excitons by Raman spectroscopy in both excited and non-excited states.Under excited states,the shifting of the Raman peak indicates the presence of the lattice distortion,which together with the extra Raman scattering peak reveals the presence of self-trapped excitons.Our work provides an alternative simple method to study self-trapped excitons in 2 D perovskites.展开更多
The broad emission and high photoluminescence quantum yield of self-trapped exciton(STE)radiative recombination emitters make them an ideal solution for single-substrate,white,solid-state lighting sources.Unlike impur...The broad emission and high photoluminescence quantum yield of self-trapped exciton(STE)radiative recombination emitters make them an ideal solution for single-substrate,white,solid-state lighting sources.Unlike impurities and defects in semiconductors,the formation of STEs requires a lattice distortion,along with strong electron–phonon coupling,in low electrondimensional materials.The photoluminescence of inorganic copper(Ⅰ)metal halides with low electron-dimensionality has been found to be the result of STEs.These materials were of significant interest because of their leadfree,all-inorganic structures,and high luminous efficiencies.In this paper,we summarize the luminescence characteristics of zero-and one-dimensional inorganic copper(I)metal halides with STEs to provide an overview of future research opportunities.展开更多
Exciton binding energy(E_(b))has been regarded as a critical parameter in charge separation during photovoltaic conversion.Minimizing the E_(b) of the photovoltaic materials can facilitate the exciton dissociation in ...Exciton binding energy(E_(b))has been regarded as a critical parameter in charge separation during photovoltaic conversion.Minimizing the E_(b) of the photovoltaic materials can facilitate the exciton dissociation in low-driving force organic solar cells(OSCs)and thus improve the power conversion efficiency(PCE);nevertheless,diminishing the E_(b) with deliberate design principles remains a significant challenge.Herein,bulky side chain as steric hindrance structure was inserted into Y-series acceptors to minimize the E_(b) by modulating the intra-and intermolecular interaction.Theoretical and experimental results indicate that steric hindrance-induced optimal intra-and intermolecular interaction can enhance molecular polarizability,promote electronic orbital overlap between molecules,and facilitate delocalized charge trans-fer pathways,thereby resulting in a low E_(b).The conspicuously reduced E_(b) obtained in Y-ChC5 with pinpoint steric hindrance modulation can minimize the detrimental effects on exciton dissociation in low-driving-force OSCs,achieving a remarkable PCE of 19.1%with over 95%internal quantum efficiency.Our study provides a new molecular design rationale to reduce the E_(b).展开更多
By using one-dimensional tight-binding model modified to include electron-electric field interaction and electron-electron interaction,we theoretically explore the polarization process of exciton and biexciton in cis-...By using one-dimensional tight-binding model modified to include electron-electric field interaction and electron-electron interaction,we theoretically explore the polarization process of exciton and biexciton in cis-polyacetylene.The dynamical simulation is performed by adopting the non-adiabatic evolution approach.The results show that under the effect of moderate electric field,when the strength of electron-electron interaction is weak,the singlet exciton is stable but its polarization presents obvious oscillation.With the enhancement of interaction,it is dissociated into polaron pairs,the spin-flip of which can be observed through modulating the interaction strength.For the triplet exciton,the strong electron-electron interaction restrains its normal polarization,but it is still stable.In the case of biexciton,the strong electron-electron interaction not only dissociate it,but also flip its charge distribution.The yield of the possible states formed after the dissociation of exciton and biexciton is also calculated.展开更多
Two-dimensional(2D)Ga_(2)O_(3)has been confirmed to be a stable structure with five atomic layer thickness configuration.In this work,we study the quasi-particle electronic band structures and then access the excitoni...Two-dimensional(2D)Ga_(2)O_(3)has been confirmed to be a stable structure with five atomic layer thickness configuration.In this work,we study the quasi-particle electronic band structures and then access the excitonic optical properties through solving the Bethe-Salpeter equation(BSE).The results reveal that the exciton dominates the optical absorption in the visible light region with the binding energy as large as~1.0 eV,which is highly stable at room temperature.Importantly,both the dominant absorption P_(1)and P_(2)peaks are optically bright without dark exciton between them,and thus is favorable for luminescence process.The calculated radiative lifetime of the lowest-energy exciton is 2.0×10^(-11)s at 0 K.Furthermore,the radiative lifetime under+4%tensile strain is one order of magnitude shorter than that of the strainfree case,while it is less insensitive under the compressive strain.Our findings set the stage for future theoretical and experimental investigation on monolayer Ga_(2)O_(3).展开更多
Quantum confinement effect and reduced dielectric screening in two-dimensional(2D)dramatically enhance theelectron-hole interactions.In this work,we use many-body perturbation theory and Bethe-Salpeter equation(BSE)to...Quantum confinement effect and reduced dielectric screening in two-dimensional(2D)dramatically enhance theelectron-hole interactions.In this work,we use many-body perturbation theory and Bethe-Salpeter equation(BSE)toinvestigate the electronic and excitonic optical properties of monolayer SnP_(2)S_(6).Our findings reveal that the excitoniceffect dominates the optical absorption spectra in the visible light range,and the lowest-energy exciton X0 in monolayerSnP_(2)S_(6)is optically bright with the binding energy of 0.87 eV and the radiative lifetime of~10^(-11)s,which is highly advantageousto the photo-luminescence.Most importantly,the absence of optically forbidden states below the bright statesX0 would give rise to a high quantum efficiency of 2D SnP_(2)S_(6).We also find that applied biaxial strain can further shortenthe radiative lifetime of the bright states.These results imply that 2D SnP_(2)S_(6)is a promising candidate for the optoelectronicdevices.展开更多
Excitons have significant impacts on the properties of semiconductors.They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping.Huybrecht variational method is a...Excitons have significant impacts on the properties of semiconductors.They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping.Huybrecht variational method is also found to influence the study of exciton ground state energy and ground state binding energy in Al_(x)Ga_(1−x)As semiconductor spherical quantum dots.The Al_(x)Ga_(1−x)As is considered to be a direct semiconductor at AI concentration below 0.45,and an indirect one at the concentration above 0.45.With regards to the former,the ground state binding energy increases and decreases with AI concentration and eigenfrequency,respectively;however,while the ground state energy increases with AI concentration,it is marginally influenced by eigenfrequency.On the other hand,considering the latter,while the ground state binding energy increases with AI concentration,it decreases with eigenfrequency;nevertheless,the ground state energy increases both with AI concentration and eigenfrequency.Hence,for the better practical performance of the semiconductors,the properties of the excitons are suggested to vary by adjusting AI concentration and eigenfrequency.展开更多
Niobic tellurite glass doped by silver chloride nanocrystal was prepared with the melting-quenching and heat treatment method, and the self-trapped exciton absorption band of the silver chloride nanocrystal was observ...Niobic tellurite glass doped by silver chloride nanocrystal was prepared with the melting-quenching and heat treatment method, and the self-trapped exciton absorption band of the silver chloride nanocrystal was observed at 532 nm in the UV-visible absorption spectrum. The glass structure characteristics were investigated by Raman spectroscopy, and the mechanism of self-trapped exciton was analyzed by Jahn-Teller model. Its optical limiting was measured with 532 nm picosecond laser pulses, and the corresponding nonlinear absorption coefficient was measured with open-aperture Z-scan. The experimental results showed that optical limiting at 532 nm was attributed to free carrier absorption between the self-trapped state and the continuum band.展开更多
We investigate the interactions of lattice pbonons with Wannier-Mott exciton, the exciton that has a large radius in two-dimensional molecular lattice, by the method of continuum limit approximation, and obtain that t...We investigate the interactions of lattice pbonons with Wannier-Mott exciton, the exciton that has a large radius in two-dimensional molecular lattice, by the method of continuum limit approximation, and obtain that the self-trapping can also appear in two-dimensional molecular lattice with a harmonic and nonlinear potential. The exciton effect on molecular lattice does not distort the molecular lattice but only makes it localized and the localization can also react, again through phonon coupling, to trap the energy and prevents its dispersion.展开更多
We investigate the interactions of lattice phonons with Frenkel exciton, which has a small radius in a twodimensional discrete molecular lattice, by the virtue of the quasi-discreteness approximation and the method of...We investigate the interactions of lattice phonons with Frenkel exciton, which has a small radius in a twodimensional discrete molecular lattice, by the virtue of the quasi-discreteness approximation and the method of multiplescale, and obtain that the self-trapping can also appear in the two-dimensional discrete molecular lattice with harmonic and nonlinear potential. The excitons＇ effect on the molecular lattice does not distort it but only causes it to localize which enables it to react again through phonon coupling to trap the energy and prevent its dispersion.展开更多
We investigate the properties of the excess charge(electron, hole) introduced into a two-strand biomolecule. We consider the possibility that the stable soliton excitation can be formed due to interaction of excess ch...We investigate the properties of the excess charge(electron, hole) introduced into a two-strand biomolecule. We consider the possibility that the stable soliton excitation can be formed due to interaction of excess charge with the phonon subsystem. The influence of overlap of the molecular orbitals between adjacent structure elements of the macromolecular chain on the soliton properties is discussed. Special attention is paid to the influence of the overlapping of the molecular orbitals between structure elements placed on the different chains. Using the literature values of the basic energy parameters of the two-chain biomolecular structures, possible types of soliton solutions are discussed.展开更多
基金supported by the Guangdong Provincial Science&Technology Project(No.2023A0505050084)the National Natural Science Foundation of China(No.22361132525)+1 种基金the Fundamental Research Funds for the Central Universities(No.2023ZYGXZR002)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01X137).
文摘Mn^(2+)doping has been adopted as an efficient approach to regulating the luminescence properties of halide perovskite nano-crystals(NCs).However,it is still difficult to understand the interplay of Mn^(2+)luminescence and the matrix self-trapped exciton(STE)emission therein.In this study,Mn^(2+)-doped CsCdCl_(3) NCs are prepared by hot injection,in which CsCdCl_(3) is selected because of its unique crystal structure suitable for STE emission.The blue emission at 441 nm of undoped CsCdCl_(3) NCs originates from the defect states in the NCs.Mn^(2+)doping promotes lattice distortion of CsCdCl_(3) and generates bright orange-red light emission at 656 nm.The en-ergy transfer from the STEs of CsCdCl_(3) to the excited levels of the Mn^(2+)ion is confirmed to be a significant factor in achieving efficient luminescence in CsCdCl_(3):Mn^(2+)NCs.This work highlights the crucial role of energy transfer from STEs to Mn^(2+)dopants in Mn^(2+)-doped halide NCs and lays the groundwork for modifying the luminescence of other metal halide perovskite NCs.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62125402 and 62321166653).
文摘Ternary metal halides based on Cu(I)and Ag(I)have attracted intensive attention in optoelectronic applications due to their excellent luminescent properties,low toxicity,and robust stability.While the self-trapped excitons(STEs)emission mechanisms of Cu(I)halides are well understood,the STEs in Ag(I)halides remain less thoroughly explored.This study explores the STE emission efficiency within the A_(2)AgX_(3)(A=Rb,Cs;X=Cl,Br,I)system by identifying three distinct STE states in each material and calculating their configuration coordinate diagrams.We find that the STE emission efficiency in this system is mainly determined by STE stability and influenced by self-trapping and quenching barriers.Moreover,we investigate the impact of structural compactness on emission efficiency and find that the excessive electron–phonon coupling in this system can be reduced by increasing the structural compactness.The atomic packing factor is identified as a low-cost and effective descriptor for predicting STE emission efficiency in both Cs_(2)AgX_(3) and Rb_(2)AgX_(3) systems.These findings can deepen our understanding of STE behavior in metal halide materials and offer valuable insights for the design of efficient STE luminescent materials.The datasets presented in this paper are openly available in Science Data Bank at https://doi.org/10.57760/sciencedb.12094.
基金supported by the National Key R&D Program of China(2016YFB070700702)the National Natural Science Foundation of China(51761145048)+1 种基金the Fundamental Research Funds for the Central Universities(HUST:2019421JYCXJJ004)the China Postdoctoral Science Foundation Grant(2019M662624).
文摘Light-emitting diodes based on lead halide perovskite have attracted great attention due to their outstanding performance.However,their application is plagued by the toxicity of Pb and the poor stability.Herein novel copper-based all inorganic perovskite CsCu2I3 with much enhanced stability has been reported with a potential photoluminescence quantum yield(PLQY)over 20%and self-trapped excitons(STE).By taking advantage of its extraordinary thermal stability,we successfully fabricate high-quality CsCu2I3 film through direct vacuum-based deposition(VBD)of CsCu2I3 powder.The resulting film shows almost the same PLQY with the synthesized powder,as well as excellent uniformity and stability.The perovskite light-emitting diodes(Pe-LED)based on the evaporated CsCu2I3 emitting layer achieve a luminescence of 10 cd/m2 and an external quantum efficiency(EQE)of 0.02%.To the best of our knowledge,this is the first CsCu2I3 Pe-LED fabricated by VBD with STE property,which offers a new avenue for lead-free Pe-LED.
基金supported by the National Natural Science Foundation of China(Nos.22175043 and 52162021)Guangxi Science and Technology Plan Project(No.Guike AA23073018)supported by the high-performance computing platform of Guangxi University。
文摘Zero-dimensional metal halides are of unique structures and tunable photoluminescence properties,showing great potential applications such as light-emitting diodes(LEDs)and sensing.Herein,we successfully synthesized Cu^(+)doped(MA)_(2)ZnCl_(4)metal halides by a slow evaporation solvent method.The introduction of Cu^(+)results in sky-blue self-trapped exciton emission in(MA)_(2)ZnCl_(4) at 486 nm at room temperature,and a photoluminescence quantum yield is as high as 54.9%.Interestingly,at low temperatures,Cu^(+)-doped(MA)_(2)ZnCl_(4) exhibits two emission peaks located at 482 and 605 nm,respectively.This temperaturedependent dual emission indicates two excited state structures that exist on the triplet excited-state potential energy surface.In addition,the temperature sensor we fitted has good performance(Sr=1.65%·K^(−1)),which is the first attempt in Cu^(+) doped Znbased metal halides.Our work enriches the family of sky-blue metal halides and provides a promising strategy for building skyblue LEDs.
基金support from the National Key R&D Program of China(No.2022YFB2803900)the National Natural Science Foundation of China(Nos.12074347,12004346,12204426,and 61935009)+1 种基金Science Foundation for Distinguished Young Scholars of Henan Province(No.212300410019)the Support Program for Scientific and Technological Innovation Teams of Higher Education in Henan Province(No.231RTSTHN012).
文摘The vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),as a newly-emerging lead-free perovskite system,has attracted great research interest due to its excellent stability and direct band gap.However,the poor luminescence performance limits its application in light-emitting diodes(LEDs)and other fields.Herein,for the first time,an Ag^(+)ion doping strategy was proposed to greatly improve the emission performance of Cs_(4)CdBi_(2)Cl_(12) synthesized by hydrothermal method.Density functional theory calculations combined with experimental results evidence that the weak orange emission from Cs_(4)CdBi_(2)Cl_(12) is attributed to the phonon scattering and energy level crossing due to the large lattice distortion under excited states.Fortunately,Ag^(+)ion doping breaks the intrinsic crystal field environment of Cs_(4)CdBi_(2)Cl_(12),suppresses the crossover between ground and excited states,and reduces the energy loss in the form of nonradiative recombination.At a critical doping amount of 0.8%,the emission intensity of Cs_(4)CdBi_(2)Cl_(12):Ag^(+)reaches the maximum,about eight times that of the pristine sample.Moreover,the doped Cs_(4)CdBi_(2)Cl_(12) still maintains excellent stability against heat,ultraviolet irradiation,and environmental oxygen/moisture.The above advantages make it possible for this material to be used as solid-state phosphors for white LEDs applications,and the Commission International de I’Eclairage color coordinates of(0.31,0.34)and high color rendering index of 90.6 were achieved.More importantly,the white LED demonstrates remarkable operation stability in air ambient,showing almost no emission decay after a long working time for 48 h.We believe that this study puts forward an effective ion-doping strategy for emission enhancement of vacancy-ordered quadruple perovskite Cs_(4)CdBi_(2)Cl_(12),highlighting its great potential as efficient emitter compatible for practical applications.
基金This work is supported by the Fund of Fujian Science&Technology Innovation Laboratory for Optoelectronic Information(Nos.2020ZZ114 and 2022ZZ204)the Key Research Program of Frontier Science CAS(No.QYZDY-SSW-SLH025)+1 种基金the National Natural Science Foundation of China(Nos.21731006 and 21871256)the Fund of Advanced Energy Science and Technology Guangdong Laboratory(No.DJLTN0200/DJLTN0240).
文摘Self-trapped excitons(STEs)emission from halide perovskites with strong exciton-phonon coupling has attracted considerable attention due to the widespread application in optoelectronic devices.Nevertheless,the in-depth understanding of the relationship between exciton-phonon coupling and luminescence intensity remains incomplete.Herein,a doping-enhanced exciton-phonon coupling effect is observed in Cs_(3)Cu_(2)I_(5)nanocrystals(NCs),which leads to a remarkable increasement of their STEs emission efficiency.Mechanism study shows that the hetero-valent substitution of Cu+with alkaline-earth metal ions(AE^(2+))causes a greater degree of Jahn-Teller distortion between the ground state and excited state structures of[Cu_(2)I_(5)]_(3)-clusters as evidenced by our spectral analysis and first-principles calculations.As a consequence,an X-ray detector based on these Cs_(3)Cu_(2)I_(5):AE NCs delivers an X-ray imaging resolution of up to 10 lp·mm^(-1) and a low detection limit of 0.37μGyair·s^(-1),disclosing the potential of doping-enhanced exciton-phonon coupling effect in improving STEs-emission and practical application for X-ray imaging.
基金supported by the Guangxi NSF(No.2020GXNSFDA238004)the Bagui Scholar project of Guangxi provincethe Scientific and Technological Bases and Talents of Guangxi(No.Guike AD21238027).
文摘Sb-based organic–inorganic hybrid metal halides(OIHMHs)with[SbCl5]2−units have been widely reported due to high photoluminescence quantum yield(PLQY)and occasional multiple self-trapped exciton(STE)emission bands mainly out of singlet and triplet states,and their multi-band emission is important in white light-emitting diode(WLED).However,not all these OIHMH compounds can produce both emissions out of singlet STE and triplet STE at room temperature simultaneously.It is crucial to consider how the singlet STE generates and retains to emit light at room temperature for this material’s design and application.Herein,a strategy is proposed that can significantly lift Sb halide PLQY by synthesizing two Sb-based OIHMHs using organic amine cations of different-sized and-quantity,which modulate the distance of neighboring emission centers.Therein,the occurrence of singlet STE emission is found to be closely related to the distance of[SbCl_(5)]^(2)−units and local unit distortion in the lattice.The larger distance can produce smaller local distortions,favoring the formation of the singlet STE emission band at higher energy.This is the first work to reveal the relationship between the local structure and the origin of the singlet STE emission band,providing new insights into the modulation of the Sb-based OIHMH’s emission.
基金D.L.acknowledges the support from the National Basic Research Program of China(No.2018YFA0704403)the National Natural Science Foundation of China(NSFC)(Grant No.61674060)Innovation Fund of Wuhan National Laboratory for Optoelectronics(WNLO).
文摘With strong electron-phonon coupling,the self-trapped excitons are usually formed in materials,which leads to the local lattice distortion and localized excitons.The self-trapping strongly depends on the dimensionality of the materials.In the three dimensional case,there is a potential barrier for self-trapping,whereas no such barrier is present for quasi-one-dimensional systems.Two-dimensional(2D)systems are marginal cases with a much lower potential barrier or nonex istent potential barrier for the self-trapping,leading to the easier formation of self-trapped states.Self-trapped excitons emission exhibits a broadband emission with a large Stokes shift below the bandgap.2D perovskites are a class of layered structure material with unique optical properties and would find potential promising optoelectronic.In particular,self-trapped excitons are present in 2D per-ovskites and can significantly influence the optical and electrical properties of 2D perovskites due to the soft characteristic and strong electron-phonon interaction.Here,we summarized the luminescence characteristics,origins,and characterizations of self-trapped excitons in 2D perovskites and finally gave an introduction to their applications in optoelectronics.
基金This work was supported by the National Natural Science Foundation of China(Nos.21661010 and 11774134)Guangxi Natural Science Foundation(No.2017GXNSFGA198005)+1 种基金Natural Science Foundation of Hunan Province(No.2020JJ4424)Research Foundation of Education Bureau of Hunan Province(No.18A009)。
文摘Perovskite variants have attracted wide interest because of the lead-free nature and strong self-trapped exciton (STE) emission. Divalent Sn(II) in CsSnX3 perovskites is easily oxidized to tetravalent Sn(IV), and the resulted Cs2SnCl6 vacancy-ordered perovskite variant exhibits poor photoluminescence property although it has a direct band gap. Controllable doping is an effective strategy to regulate the optical properties of Cs2SnX6. Herein, combining the first principles calculation and spectral analysis, we attempted to understand the luminescence mechanism of Te4+-doped Cs2SnCl6 lead-free perovskite variants. The chemical potential and defect formation energy are calculated to confirm theoretically the feasible substitutability of tetravalent Te4+ ions in Cs2SnCl6 lattices for the Sn-site. Through analysis of the absorption, emission/excitation, and time-resolved photoluminescence (PL) spectroscopy, the intense green-yellow emission in Te4+:Cs2SnCl6 was considered to originate from the triplet Te(IV) ion 3P1→1S0 STE recombination. Temperature-dependent PL spectra demonstrated the strong electron-phonon coupling that inducing an evident lattice distortion to produce STEs. We further calculated the electronic band structure and molecular orbital levels to reveal the underlying photophysical process. These results will shed light on the doping modulated luminescence properties in stable lead-free Cs2MX6 vacancy-ordered perovskite variants and be helpful to understand the optical properties and physical processes of doped perovskite variants.
基金supported by the National Key Research and Development Program of China(No.2018YFA0704403)National Natural Science Foundation of China(NSFC)(No.62074064)+2 种基金Innovation Fund of WNLO,Key Laboratory of Nanodevices and Applications,Suzhou Institute of NanoTech and Nano-Bionics,Chinese Academy of Sciences(No.19ZS03)China Postdoctoral Science Foundation(No.2020M682399)Postdoctoral Innovation Fund of Hubei Province。
文摘Two-dimensional(2D)perovskites exhibit broadband emission due to strong exciton–phonon coupling-induced self-trapped excitons and thus would find important applications in the field of white-light emitting devices.However,the available identifying methods for self-trapped excitons are currently rather limited and complex.Here,we identify the existence of self-trapped excitons by Raman spectroscopy in both excited and non-excited states.Under excited states,the shifting of the Raman peak indicates the presence of the lattice distortion,which together with the extra Raman scattering peak reveals the presence of self-trapped excitons.Our work provides an alternative simple method to study self-trapped excitons in 2 D perovskites.
基金the National Key Research and Development Plan of China(No.2019YFE0107200)the National Natural Science Foundation of China(Grant No.11705277),the Natural Science Foundation of Hubei Province(No.2020CFB700)+1 种基金the Doctoral Research Foundation Project of Hubei University of Arts and Science(No.kyqdf2020023)Innovation Research Team Project of Hubei University of Arts and Science(No.2020kypytd001).
文摘The broad emission and high photoluminescence quantum yield of self-trapped exciton(STE)radiative recombination emitters make them an ideal solution for single-substrate,white,solid-state lighting sources.Unlike impurities and defects in semiconductors,the formation of STEs requires a lattice distortion,along with strong electron–phonon coupling,in low electrondimensional materials.The photoluminescence of inorganic copper(Ⅰ)metal halides with low electron-dimensionality has been found to be the result of STEs.These materials were of significant interest because of their leadfree,all-inorganic structures,and high luminous efficiencies.In this paper,we summarize the luminescence characteristics of zero-and one-dimensional inorganic copper(I)metal halides with STEs to provide an overview of future research opportunities.
基金National Natural Science Foundation of China,Grant/Award Numbers:52203225,52073122,22375077,22008184Key R&D Project of Hubei Province,Grant/Award Number:2022BAA095+3 种基金Hubei Natural Science Foundation,Grant/Award Number:2022CFB903Special Project from Jianghan University,Grant/Award Number:2022XKZX02Ministry of Science and Technology of China,Grant/Award Number:2021YFE0113600Excellent Discipline Cultivation Project by JHUN,Grant/Award Numbers:2023XKZ010,2023XKZ014。
文摘Exciton binding energy(E_(b))has been regarded as a critical parameter in charge separation during photovoltaic conversion.Minimizing the E_(b) of the photovoltaic materials can facilitate the exciton dissociation in low-driving force organic solar cells(OSCs)and thus improve the power conversion efficiency(PCE);nevertheless,diminishing the E_(b) with deliberate design principles remains a significant challenge.Herein,bulky side chain as steric hindrance structure was inserted into Y-series acceptors to minimize the E_(b) by modulating the intra-and intermolecular interaction.Theoretical and experimental results indicate that steric hindrance-induced optimal intra-and intermolecular interaction can enhance molecular polarizability,promote electronic orbital overlap between molecules,and facilitate delocalized charge trans-fer pathways,thereby resulting in a low E_(b).The conspicuously reduced E_(b) obtained in Y-ChC5 with pinpoint steric hindrance modulation can minimize the detrimental effects on exciton dissociation in low-driving-force OSCs,achieving a remarkable PCE of 19.1%with over 95%internal quantum efficiency.Our study provides a new molecular design rationale to reduce the E_(b).
基金Project supported by the Natural Science Foundation of Shandong Province,China(Grant No.ZR2020MA070).
文摘By using one-dimensional tight-binding model modified to include electron-electric field interaction and electron-electron interaction,we theoretically explore the polarization process of exciton and biexciton in cis-polyacetylene.The dynamical simulation is performed by adopting the non-adiabatic evolution approach.The results show that under the effect of moderate electric field,when the strength of electron-electron interaction is weak,the singlet exciton is stable but its polarization presents obvious oscillation.With the enhancement of interaction,it is dissociated into polaron pairs,the spin-flip of which can be observed through modulating the interaction strength.For the triplet exciton,the strong electron-electron interaction restrains its normal polarization,but it is still stable.In the case of biexciton,the strong electron-electron interaction not only dissociate it,but also flip its charge distribution.The yield of the possible states formed after the dissociation of exciton and biexciton is also calculated.
基金supported by the National Natural Science Foundation of China(Grant No.12064032).
文摘Two-dimensional(2D)Ga_(2)O_(3)has been confirmed to be a stable structure with five atomic layer thickness configuration.In this work,we study the quasi-particle electronic band structures and then access the excitonic optical properties through solving the Bethe-Salpeter equation(BSE).The results reveal that the exciton dominates the optical absorption in the visible light region with the binding energy as large as~1.0 eV,which is highly stable at room temperature.Importantly,both the dominant absorption P_(1)and P_(2)peaks are optically bright without dark exciton between them,and thus is favorable for luminescence process.The calculated radiative lifetime of the lowest-energy exciton is 2.0×10^(-11)s at 0 K.Furthermore,the radiative lifetime under+4%tensile strain is one order of magnitude shorter than that of the strainfree case,while it is less insensitive under the compressive strain.Our findings set the stage for future theoretical and experimental investigation on monolayer Ga_(2)O_(3).
基金support by the National Natural Science Foundation of China(Grant No.12064032).
文摘Quantum confinement effect and reduced dielectric screening in two-dimensional(2D)dramatically enhance theelectron-hole interactions.In this work,we use many-body perturbation theory and Bethe-Salpeter equation(BSE)toinvestigate the electronic and excitonic optical properties of monolayer SnP_(2)S_(6).Our findings reveal that the excitoniceffect dominates the optical absorption spectra in the visible light range,and the lowest-energy exciton X0 in monolayerSnP_(2)S_(6)is optically bright with the binding energy of 0.87 eV and the radiative lifetime of~10^(-11)s,which is highly advantageousto the photo-luminescence.Most importantly,the absence of optically forbidden states below the bright statesX0 would give rise to a high quantum efficiency of 2D SnP_(2)S_(6).We also find that applied biaxial strain can further shortenthe radiative lifetime of the bright states.These results imply that 2D SnP_(2)S_(6)is a promising candidate for the optoelectronicdevices.
基金supported by the National Natural Science Foundation of China(Nos.12164032 and 11964026)the Natural Science Foundation of Inner Mongolia(No.2019MS01010)+3 种基金Scientific Research Projects in Colleges and Universities in Inner Mongolia(No.NJZZ19145)Graduate Science Innovative Research Projects(No.S20210281Z)the Natural Science Foundation of Inner Mongolia(No.2022MS01014)Doctor Research Start-up Fund of Inner Mongolia Minzu University(No.BS625).
文摘Excitons have significant impacts on the properties of semiconductors.They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping.Huybrecht variational method is also found to influence the study of exciton ground state energy and ground state binding energy in Al_(x)Ga_(1−x)As semiconductor spherical quantum dots.The Al_(x)Ga_(1−x)As is considered to be a direct semiconductor at AI concentration below 0.45,and an indirect one at the concentration above 0.45.With regards to the former,the ground state binding energy increases and decreases with AI concentration and eigenfrequency,respectively;however,while the ground state energy increases with AI concentration,it is marginally influenced by eigenfrequency.On the other hand,considering the latter,while the ground state binding energy increases with AI concentration,it decreases with eigenfrequency;nevertheless,the ground state energy increases both with AI concentration and eigenfrequency.Hence,for the better practical performance of the semiconductors,the properties of the excitons are suggested to vary by adjusting AI concentration and eigenfrequency.
基金Supported by Shanghai Leading Academic Discipline Project (Grant No. B408)National Basic Research Program of China (Grant Nos. 2006CB806006, 2006CB921105)+1 种基金Program for Changjiang Scholars and Innovative Research Team in University, Doctoral Program of High Education (Grant No. 20050269011)Project sponsored by Shanghai Science and Technology Committee (Grant Nos. 06DJ14008, 07dz22025, 06QH14003)
文摘Niobic tellurite glass doped by silver chloride nanocrystal was prepared with the melting-quenching and heat treatment method, and the self-trapped exciton absorption band of the silver chloride nanocrystal was observed at 532 nm in the UV-visible absorption spectrum. The glass structure characteristics were investigated by Raman spectroscopy, and the mechanism of self-trapped exciton was analyzed by Jahn-Teller model. Its optical limiting was measured with 532 nm picosecond laser pulses, and the corresponding nonlinear absorption coefficient was measured with open-aperture Z-scan. The experimental results showed that optical limiting at 532 nm was attributed to free carrier absorption between the self-trapped state and the continuum band.
基金supported by the National Natural Science Foundation of China (Grant No.1057400)the Natural Science Foundation of Heilongjiang Province,China (Grant No.A200506)
文摘We investigate the interactions of lattice pbonons with Wannier-Mott exciton, the exciton that has a large radius in two-dimensional molecular lattice, by the method of continuum limit approximation, and obtain that the self-trapping can also appear in two-dimensional molecular lattice with a harmonic and nonlinear potential. The exciton effect on molecular lattice does not distort the molecular lattice but only makes it localized and the localization can also react, again through phonon coupling, to trap the energy and prevents its dispersion.
基金supported by the National Natural Science Foundation of China (Grant No 1057400)the Natural Science Foundation of Heilongjiang Province of China (Grant No A200506)
文摘We investigate the interactions of lattice phonons with Frenkel exciton, which has a small radius in a twodimensional discrete molecular lattice, by the virtue of the quasi-discreteness approximation and the method of multiplescale, and obtain that the self-trapping can also appear in the two-dimensional discrete molecular lattice with harmonic and nonlinear potential. The excitons＇ effect on the molecular lattice does not distort it but only causes it to localize which enables it to react again through phonon coupling to trap the energy and prevent its dispersion.
基金Project supported by the Ministry of Education,Science and Technological Development of the Republic of Serbiathe Ministry of Science and Higher Education of the Russian Federation in the framework of Increase Competitiveness Program of NUST “MISiS” (Grant No.K2-2019-010)the Project within the Cooperation Agreement between the JINR,Dubna,Russian Federation and Ministry of Education and Science of the Republic of Serbia。
文摘We investigate the properties of the excess charge(electron, hole) introduced into a two-strand biomolecule. We consider the possibility that the stable soliton excitation can be formed due to interaction of excess charge with the phonon subsystem. The influence of overlap of the molecular orbitals between adjacent structure elements of the macromolecular chain on the soliton properties is discussed. Special attention is paid to the influence of the overlapping of the molecular orbitals between structure elements placed on the different chains. Using the literature values of the basic energy parameters of the two-chain biomolecular structures, possible types of soliton solutions are discussed.
