Twist,the very degree of freedom in van der Waals heterostructures,offers a compelling avenue to manipulate and tailor their electrical and optical characteristics.In particular,moirépatterns in twisted homobilay...Twist,the very degree of freedom in van der Waals heterostructures,offers a compelling avenue to manipulate and tailor their electrical and optical characteristics.In particular,moirépatterns in twisted homobilayer transition metal dichalcogenides(TMDs)lead to zone folding and miniband formation in the resulting electronic bands,holding the promise to exhibit inter-layer excitonic optical phenomena.Although some experiments have shown the existence of twist-angle-dependent intra-and inter-layer excitons in twisted MoSe2 homobilayers,electrical control of the interlayer excitons in MoSe_(2) is relatively under-explored.Here,we show the signatures of the moiréeffect on intralayer and interlayer excitons in 2H-stacked twisted MoSe2 homobilayers.Doping-and electric field-dependent photoluminescence mea-surements at low temperatures give evidence of the momentum-direct K-K intralayer excitons,and the momentum-indirect Г-K and Г-Q interlayer excitons.Our results suggest that twisted MoSe_(2) homobilayers are an intriguing platform for engineering interlayer exciton states,which may shed light on future atomically thin optoelectronic applications.展开更多
Insight into exciton dynamics of two-dimensional(2D)transition metal dichalcogenides(TMDs)is critical for the optimization of their performance in photonic and optoelectronic devices.Although current researches have p...Insight into exciton dynamics of two-dimensional(2D)transition metal dichalcogenides(TMDs)is critical for the optimization of their performance in photonic and optoelectronic devices.Although current researches have primarily concentrated on the near-resonant excitation scenario in 2D TMDs,the case of excitation energies resonating with highenergy excitons or higher energies has yet to be fully elucidated.Here,a comparative analysis is conducted between highenergy excitation(360 nm)and near-resonant excitation(515 nm)utilizing transient absorption spectroscopy to achieve a comprehensive understanding of the exciton dynamics within monolayer WS_(2).It is observed that the high-energy C-exciton can be generated via an up-conversion process under 515 nm excitation,even the energy of which is less than that of the C-exciton.Furthermore,the capacity to efficiently occupy band-edge A-exciton states leads to longer lifetimes for both the C-excitons and the A-excitons under conditions of near-resonant excitation,accompanied by an augmented rate of radiative recombination.This study provides a paradigm for optimizing the performance of 2D TMDs-based devices by offering valuable insights into their exciton dynamics.展开更多
Organic photovoltaics(OPVs)have achieved remarkable progress,with laboratory-scale single-junction devices now demonstrating power conversion efficiencies(PCEs)exceeding 20%.However,these efficiencies are highly depen...Organic photovoltaics(OPVs)have achieved remarkable progress,with laboratory-scale single-junction devices now demonstrating power conversion efficiencies(PCEs)exceeding 20%.However,these efficiencies are highly dependent on the thickness of the photoactive layer,which is typically around 100 nm.This sensitivity poses a challenge for industrial-scale fabrication.Achieving high PCEs in thick-film OPVs is therefore essential.This review systematically examines recent advancements in thick-film OPVs,focusing on the fundamental mechanisms that lead to efficiency loss and strategies to enhance performance.We provide a comprehensive analysis spanning the complete photovoltaic process chain:from initial exciton generation and diffusion dynamics,through dissociation mechanisms,to subsequent charge-carrier transport,balance optimization,and final collection efficiency.Particular emphasis is placed on cutting-edge solutions in molecular engineering and device architecture optimization.By synthesizing these interdisciplinary approaches and investigating the potential contributions in stability,cost,and machine learning aspects,this work establishes comprehensive guidelines for designing high-performance OPVs devices with minimal thickness dependence,ultimately aiming to bridge the gap between laboratory achievements and industrial manufacturing requirements.展开更多
Carbon dots(CDs),due to their low cost,high stability,and high luminous efficiency,have emerged as an excellent material for the emissive layer in next-generation electroluminescent light-emitting diodes(ELEDs).Howeve...Carbon dots(CDs),due to their low cost,high stability,and high luminous efficiency,have emerged as an excellent material for the emissive layer in next-generation electroluminescent light-emitting diodes(ELEDs).However,improving the efficiency of fluorescent CDs-based ELEDs remains challenging,primarily because it is difficult to utilize triplet excitons in the electroluminescence process.Therefore,enhancing the exciton utilization efficiency of CDs during electroluminescence is crucial.Based on this,we exploited the characteristic large exciton binding energy commonly found in CDs to develop exciton-emitting CDs.These CDs facilitate the radiative recombination of excitons during electroluminescence,thereby improving the electroluminescent efficiency.By rationally selecting precursors,we developed high quantum efficiency CDs and subsequently constructed CDs-based ELEDs.The blue-light device exhibited an external quantum efficiency of over 4%.This study introduces a novel design concept for CDs,providing a new strategy for developing high-performance blue ELEDs based on CDs.展开更多
We investigate electronic structures and excitonic properties of monolayer SiP_(2)within the framework of firstprinciples GW plus Bethe-Salpeter equation(GW-BSE)calculations.Within the G_(0)W_(0)approximation,monolaye...We investigate electronic structures and excitonic properties of monolayer SiP_(2)within the framework of firstprinciples GW plus Bethe-Salpeter equation(GW-BSE)calculations.Within the G_(0)W_(0)approximation,monolayer SiP_(2)is identified as a direct-gap semiconductor with an electronic gap of 3.14 e V,and the excitons exhibit a hybrid-dimensional character similar to that of the bulk counterpart.The optical absorption spectra reveal pronounced excitonic effects with strong anisotropy:the first bright exciton has a binding energy of 840 meV under x-polarized light,compared with 450 meV under y-polarized light.We further analyze the symmetry origins of the polarization-dependent optical selection rules through group theory.This binding energy difference arises from the intrinsic nature of the excitons:flat-band excitons under x-polarized light and conventional excitons localized at a single k point under y-polarized light.Our work enhances the understanding of excitonic behavior in monolayer SiP_(2)and highlights its potential for polarization-sensitive and directionally tunable optoelectronic applications.展开更多
Understanding interlayer charge transfer is crucial for elucidating interface interactions in heterostructures.As the layer number can significantly influence the interface coupling and band alignment,the charge trans...Understanding interlayer charge transfer is crucial for elucidating interface interactions in heterostructures.As the layer number can significantly influence the interface coupling and band alignment,the charge transfer behaviors can be largely regulated.Here,we constructed two-dimensional(2D)heterostructures consisting of monolayer WS_(2)and few-layer InSe to investigate the impact of InSe thickness on exciton dynamics.We performed photoluminescence(PL)spectroscopy and lifetime measurements on pristine few-layer InSe and the heterostructures with different InSe thicknesses.For pristine InSe layers,we found a non-monotonic layer dependence on PL lifetime,which can be attributed to the interplay between the indirect-to-direct bandgap transition and surface recombination effects.For heterostructures,we demonstrated that the type I band alignment of the heterostructure facilitates electron and hole transfer from monolayer WS_(2)to InSe.As the InSe layer number increases,the reduction in conduction band minimum(CBM)enhances the driving force for charge transfer,thereby improving the transfer efficiency.Furthermore,we fabricated and characterized a WS_(2)/InSe optoelectronic device.By analyzing bias voltage dependent PL spectra,we further demonstrated that the trions in WS_(2)within the heterostructure are positively charged(X^(+)),and their emission intensity can be efficiently modulated by applying different biases.This study not only reveals the layer-dependent characteristics of band alignment and interlayer charge transfer in heterostructures but also provides valuable insights for the applications of 2D semiconductors in optoelectronic devices.展开更多
The excitonic insulator(EI)is a more than 60-year-old theoretical proposal that is still elusive.It is a purely quantum phenomenon involving the spontaneous generation of excitons in quantum mechanics and the spontane...The excitonic insulator(EI)is a more than 60-year-old theoretical proposal that is still elusive.It is a purely quantum phenomenon involving the spontaneous generation of excitons in quantum mechanics and the spontaneous condensation of excitons in quantum statistics.At this point,the excitons represent the ground state rather than the conventional excited state.Thus,the scarcity of candidate materials is a key factor contributing to the lack of recognized EI to date.In this review,we begin with the birth of EI,presenting the current state of the field and the main challenges it faces.We then focus on recent advances in the discovery and design of EIs based on the first-principles Bethe-Salpeter scheme,in particular the dark-exciton rule guided screening of materials.It not only opens up new avenues for realizing excitonic instability in direct-gap and wide-gap semiconductors,but also leads to the discovery of novel quantum states of matter such as half-EIs and spin-triplet EIs.Finally,we will look ahead to possible research pathways leading to the first recognized EI,both theoretically and computationally.展开更多
In moiré-patterned van der Waals structures of transition metal dichalcogenides,correlated insulators can form under integer and fractional fillings,whose transport properties are governed by various quasiparticl...In moiré-patterned van der Waals structures of transition metal dichalcogenides,correlated insulators can form under integer and fractional fillings,whose transport properties are governed by various quasiparticle excitations including holons,doublons and interlayer exciton insulators.Here we theoretically investigate the nearest-neighbor inter-site hoppings of holons and interlayer exciton insulators.Our analysis indicates that these hopping strengths are significantly enhanced compared to that of a single carrier.The underlying mechanism can be attributed to the strong Coulomb interaction between carriers at different sites.For the interlayer exciton insulator consisting of a holon and a carrier in different layers,we have also obtained its effective Bohr radius and energy splitting between the ground and the first-excited states.展开更多
Two-dimensional(2D)transition-metal dichalcogenide(TMD)monolayers based on become a promising platform to study photonics and optoelectronics.Electrically controlling the excitonic properties of TMD monolayers can be ...Two-dimensional(2D)transition-metal dichalcogenide(TMD)monolayers based on become a promising platform to study photonics and optoelectronics.Electrically controlling the excitonic properties of TMD monolayers can be realized in different devices.In this work,we realize the strong coupling between the excitons of WS_(2)monolayers and a photonic cavity mode in a liquid crystal microcavity.The formed exciton polaritons can be electrically tuned by applying voltage to the microcavity.Our work offers a way to study exciton-polariton manipulation based on TMD monolayers by electrical methods at room temperature.展开更多
Efficient exciton transport over long distances is crucial for organic optoelectronics.Despite efforts to improve the transport properties of organic semiconductors,the limited exciton diffusion remains a significant ...Efficient exciton transport over long distances is crucial for organic optoelectronics.Despite efforts to improve the transport properties of organic semiconductors,the limited exciton diffusion remains a significant obstacle for light-harvesting applications.In this study,we observe phenomena where exciton transport is significantly enhanced by light irradiation in the organic molecular crystal of 2,2'-(2,5-bis(2,2-diphenylvinyl)-1,4-phenylene)dinaphthalene(BDVPN).The exciton transport in this material is improved,as evidenced by the increased diffusion coefficient from 10^(−3) cm^(2)·s^(−1) to over 1 cm^(2)·s^(−1) and a prolonged diffusion length from less than 50 nm to nearly 700 nm characterized by time-resolved photoluminescence microscopy(TPLM).Additionally,we confirmed the enhancement of charge transport capability under irradiation as additional evidence of improved transport properties of the material.These intriguing phenomena may be associated with the material’s twisted molecular conformation and rotatable single bonds,which facilitate light-induced structural alterations conducive to efficient transport properties.Our work provides a novel insight into developing organic semiconductors with efficient exciton transport.展开更多
Two-dimensional(2D)transition metal dichalcogenides(TMDs),endowed with exceptional light-matter interaction strength,have become a pivotal platform in advanced optoelectronics,enabling atomically precise control of ex...Two-dimensional(2D)transition metal dichalcogenides(TMDs),endowed with exceptional light-matter interaction strength,have become a pivotal platform in advanced optoelectronics,enabling atomically precise control of excitonic phenomena and offering transformative potential for engineering next-generation optoelectronic devices.In contrast to the narrowband absorption characteristics of conventional band-edge excitons,which are limited by the bandgap energy,highenergy excitons not only demonstrate broad momentum matching capability in the ultraviolet regime due to band nesting effects,but also exhibit distinct absorption peak signatures owing to robust excitonic stabilization under 2D confinement.These unique photophysical properties have established such systems as a prominent research frontier in contemporary exciton physics.This review primarily outlines the distinctive physical characteristics of high-energy excitons in TMDs from the perspectives of band structure,excitonic characteristics,and optical properties.Subsequently,we systematically delineate cutting-edge developments in TMD-based photonic devices exploiting high-energy excitonic band-nesting phenomena,with dedicated emphasis on the strategic engineering of nanoscale heterostructures for tailored optoelectronic functionality.Finally,the discussion concludes with an examination of the challenges associated with the design of high-energy exciton devices and their potential future applications.展开更多
Transition metal dichalcogenide(TMDC)monolayers provide an ideal platform for exciton and valley-spintronics exploration due to their unique properties.Integrating TMDC monolayers with conventional semiconductors allo...Transition metal dichalcogenide(TMDC)monolayers provide an ideal platform for exciton and valley-spintronics exploration due to their unique properties.Integrating TMDC monolayers with conventional semiconductors allows for harnessing the unique properties of both materials.This strategy holds great promise for the development of advanced optoelectronics and spintronic devices.In this work,we investigated exciton and valley dynamics in WSe_(2)/Ga As heterostructure by employing the femtosecond pump-probe ultrafast spectroscopy.Facilitated by the charge transfer within the heterostructure,it was found that the exciton of WSe_(2)exhibited much longer lifetime of nanosecond than that of the WSe_(2)monolayer counterpart.Especially,a significantly long valley lifetime up to~2.7 ns was observed for trions of WSe_(2)in the heterostructure even under the off-resonant excitation,which is found to be associated with the resident electrons accumulated at the interface resulting from the charge transfer and resultant interfacial electric field.Our results provide fundamental references for conventional semiconductor-integrated TMDC heterostructures that have great potential for designing novel optoelectronic and spintronic devices.展开更多
Correction to:Nano-Micro Letters(2026)18:10.https://doi.org/10.1007/s40820-025-01852-8 Following publication of the original article[1],the authors reported that the last author’s name was inadvertently misspelled.Th...Correction to:Nano-Micro Letters(2026)18:10.https://doi.org/10.1007/s40820-025-01852-8 Following publication of the original article[1],the authors reported that the last author’s name was inadvertently misspelled.The published version showed“Hongzhen Chen”,whereas the correct spelling should be“Hongzheng Chen”.The correct author name has been provided in this Correction,and the original article[1]has been corrected.展开更多
Solar-driven hydrogen peroxide(H_(2)O_(2))production offers a sustainable and environmentally friendly alternative to the traditional anthraquinone oxidation method.Conjugated polymers(CPs)are emerging as promising ph...Solar-driven hydrogen peroxide(H_(2)O_(2))production offers a sustainable and environmentally friendly alternative to the traditional anthraquinone oxidation method.Conjugated polymers(CPs)are emerging as promising photocatalysts for H_(2)O_(2)production due to their unique electronic,optical properties,and tunable structures.However,the high exciton binding energy of CPs hinders efficient exciton dissociation and charge separation,limiting their photocatalytic performance.In this work,we synthesized scandium(Sc)atoms decorated CPs with enhanced ordered stacking and crystallinity by introducing benzaldehyde as an end-capping reagent.The strong interaction between charged Sc atoms and electrons facilitates exciton dissociation and improves charge transfer capability.Furthermore,the Lewis acidic nature of Sc atoms promotes oxygen adsorption and enhances the stabilization of superoxide anion intermediate(·O_(2)^(-)).As a result,the as-synthesized photocatalysts exhibit a high H_(2)O_(2)production rate of 18μmol h^(-1)in pure water,which is three times that of pristine CPs,This work provides valuable insights into the design of organic polymer photocatalysts for various photocatalytic reactions.展开更多
Focusing on the mechanism of interfa-cial exciton dissociation in edge-on stacked ZnPc-F_(8)ZnPc aggregate,we employ the fragment particle-hole densities(FPHD)method to con-struct the Hamiltonian of diabatic states an...Focusing on the mechanism of interfa-cial exciton dissociation in edge-on stacked ZnPc-F_(8)ZnPc aggregate,we employ the fragment particle-hole densities(FPHD)method to con-struct the Hamiltonian of diabatic states and use the non-Markovian stochastic Schrödinger equation(NMSSE)to simulate the photo-in-duced dynamics processes.The re-sults show that aggregation effects have a significant impact on the interfacial exciton dissociation process.After photo-excita-tion,the excitons first preferentially delocalize and perform the charge transfer(CT)states in the pure ZnPc or F_(8)ZnPc aggregates within 100 fs.These‘intramolecular’CT states can easi-ly evolve into interfacial CT states by hopping electrons and holes in the intramolecular CT states across the interface.Compared with these exciton dissociation processes,the direct ex-citon dissociation into interfacial CT state is relatively slow due to the small electronic cou-pling and vibrational coherence between the locally excited state and the interfacial CT state.As the temperature rises and the vibronic coherence weakens,the direct dissociation rates are significantly enhanced.This investigation provides valuable insights for the design and opti-mization of high-performance organic photovoltaic devices.展开更多
Supersolidity is a counterintuitive quantum phase of matter where the long-range spatial order of a solid coexists with the frictionless flow characteristic of a superfluid.Recently,evidence of supersolidity has been ...Supersolidity is a counterintuitive quantum phase of matter where the long-range spatial order of a solid coexists with the frictionless flow characteristic of a superfluid.Recently,evidence of supersolidity has been demonstrated in polariton condensates in III-V photonic crystal microcavities by condensing into a topological bound state in the continuum,offering a new light-matter hybrid platform for exploring such quantum phase.In this work,we propose a theoretical scheme for realizing room-temperature supersolidity based on halide perovskite exciton polaritons operating in the optical parametric oscillation regime.By employing a waveguide microcavity geometry,we confine polariton scattering direction in reciprocal space,enabling controlled momentum selection.Leveraging the intrinsic nonlinear interactions among polaritons,we theoretically demonstrate the spontaneous breaking of both continuous translational symmetry and global phase symmetry,i.e.,the evidence of supersolidity.Furthermore,we identify a tunable phase transition sequence in our system:from a Bose-Einstein condensate to a supersolid phase,and ultimately to an insulating phase,as the nonlinear interaction strength increases.展开更多
Semiconductor moirésuperlattices provide great platforms for exploring exotic collective excitations.Optical Stark effect,a shift of the electronic transition in the presence of a light field,provides an ultrafas...Semiconductor moirésuperlattices provide great platforms for exploring exotic collective excitations.Optical Stark effect,a shift of the electronic transition in the presence of a light field,provides an ultrafast and coherent method of manipulating matter states,which,however,has not been demonstrated in moirématerials.Here,we report the valleyselective optical Stark effect of moiréexcitons in the WSe_(2)/WS_(2)superlattice by using transient reflection spectroscopy.Prominent valley-selective energy shifts up to 7.8 meV have been observed for moiréexcitons,corresponding to pseudomagnetic fields as large as 34 T.Our results provide a route to coherently manipulate exotic states in moirésuperlattices.展开更多
Electron-hole interactions play a crucial role in determining the optoelectronic properties of materials,and in lowdimensional systems this is especially true due to the decrease of screening.In this review,we focus o...Electron-hole interactions play a crucial role in determining the optoelectronic properties of materials,and in lowdimensional systems this is especially true due to the decrease of screening.In this review,we focus on one unique quantum phase induced by the electron-hole interaction in two-dimensional systems,known as“exciton insulators”(EIs).Although this phase of matter has been studied for more than half a century,suitable platforms for its stable realization remain scarce.We provide an overview of the strategies to realize EIs in accessible materials and structures,along with a discussion on some unique properties of EIs stemming from the band structures of these materials.Additionally,signatures in experiments to distinguish EIs are discussed.展开更多
Carbon nitride,a typical low-dimensional conjugated polymer photocatalyst,features a high exciton binding energy due to the weak dielectric screening and the strong Coulombic attraction of photogenerated electrons and...Carbon nitride,a typical low-dimensional conjugated polymer photocatalyst,features a high exciton binding energy due to the weak dielectric screening and the strong Coulombic attraction of photogenerated electrons and holes.The reduction of the exciton binding energy of carbon nitride to promote the conversion from excitons into free carriers is the first priority for the improvement of charge-transfer-dependent photocatalytic reaction activity.In this paper,by introducing a variety of polar metal cations to carbon nitride,it is demonstrated that the charge distribution of the heptazine ring can be improved by ion polarization,which effectively promotes the dissociation of excitons into electrons and holes.The sodium ion shows the best modification effect,which enhances the rate of both photocatalytic hydrogen and hydrogen peroxide production by about 50%.Characterization shows that the introduction of strongly polar metal cations contributes to the reduction of the exciton dissociation energy of carbon nitride.This study provides a new perspective and a convenient method for the exciton modulation engineering of low-dimensional photocatalysts.展开更多
We report a mechanistic study of excitonic photoluminescence in predesigned hybrid organic-inorganic perovskite(HOIP)systems,i.e.,(DMAEA)Pb_(2)I_(6),(DMAPA)PbI_(4),(DEAEA)Pb_(2)I_(6),and(DEAPA)_(4)Pb_(5)I_(18),featuri...We report a mechanistic study of excitonic photoluminescence in predesigned hybrid organic-inorganic perovskite(HOIP)systems,i.e.,(DMAEA)Pb_(2)I_(6),(DMAPA)PbI_(4),(DEAEA)Pb_(2)I_(6),and(DEAPA)_(4)Pb_(5)I_(18),featuring targeted regulation of organic cations.Starting from the prototype DMAEA(i.e.,2-N,N-dimethylamino-l-ethylamine)for(DMAEA)Pb_(2)I_(6),the other three HOIPs differ only in the extensions with CH_(2)group(s)at the“head”or/and“tail”of DMAEA that is an“alkylated ammonia”.Their crystal structures are constructed and structural distortions are evaluated.The steady-state/transient absorption and emission spectroscopic characterizations,combined with the band-structure calculations,are conducted.The two different photoluminescence(PL)mechanisms are identified,i.e.,PL emissions dominated by free excitons for(DMAPA)PbI_(4)and by self-trapped excitons for(DMAEA)Pb_(2)I_(6),(DEAEA)Pb_(2)I_(6),and(DEAPA)_(4)Pb_(5)I_(18).The self-trapped excitonic effect involved in the latter three HOIPs is quantitatively analyzed.This work would be of guiding value for the design of HOIP systems based on organic-cation engineering,beneficial for the pertinent performance optimization in light-emitting applications.展开更多
基金supported by the National Key R&D Program of China(No.2023YFF1500600)the National Natural Science Foun-dation of China(Nos.12004259,12204287)+3 种基金China Postdoc-toral Science Foundation(Grant No.2022M723215)Zheng Vitto Han acknowledges the support of the Fund for Shanxi“1331 Project”Key Subjects Construction,and the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302003)Kenji Watanabe and Takashi Taniguchi acknowledge support from the JSPS KAKENHI(Grant Nos.20H00354 and 23H02052)the World Premier International Research Center Initiative(WPI),MEXT,Japan.
文摘Twist,the very degree of freedom in van der Waals heterostructures,offers a compelling avenue to manipulate and tailor their electrical and optical characteristics.In particular,moirépatterns in twisted homobilayer transition metal dichalcogenides(TMDs)lead to zone folding and miniband formation in the resulting electronic bands,holding the promise to exhibit inter-layer excitonic optical phenomena.Although some experiments have shown the existence of twist-angle-dependent intra-and inter-layer excitons in twisted MoSe2 homobilayers,electrical control of the interlayer excitons in MoSe_(2) is relatively under-explored.Here,we show the signatures of the moiréeffect on intralayer and interlayer excitons in 2H-stacked twisted MoSe2 homobilayers.Doping-and electric field-dependent photoluminescence mea-surements at low temperatures give evidence of the momentum-direct K-K intralayer excitons,and the momentum-indirect Г-K and Г-Q interlayer excitons.Our results suggest that twisted MoSe_(2) homobilayers are an intriguing platform for engineering interlayer exciton states,which may shed light on future atomically thin optoelectronic applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.12474421 and 12104066)the Fund from Education Department of Jilin Province(Grant Nos.JJKH20250473KJ and JJKH20241413KJ)the Fund from Department of Science and Technology of Jilin Province(Grant No.YDZJ202101ZYTS041)。
文摘Insight into exciton dynamics of two-dimensional(2D)transition metal dichalcogenides(TMDs)is critical for the optimization of their performance in photonic and optoelectronic devices.Although current researches have primarily concentrated on the near-resonant excitation scenario in 2D TMDs,the case of excitation energies resonating with highenergy excitons or higher energies has yet to be fully elucidated.Here,a comparative analysis is conducted between highenergy excitation(360 nm)and near-resonant excitation(515 nm)utilizing transient absorption spectroscopy to achieve a comprehensive understanding of the exciton dynamics within monolayer WS_(2).It is observed that the high-energy C-exciton can be generated via an up-conversion process under 515 nm excitation,even the energy of which is less than that of the C-exciton.Furthermore,the capacity to efficiently occupy band-edge A-exciton states leads to longer lifetimes for both the C-excitons and the A-excitons under conditions of near-resonant excitation,accompanied by an augmented rate of radiative recombination.This study provides a paradigm for optimizing the performance of 2D TMDs-based devices by offering valuable insights into their exciton dynamics.
基金supported by Natural Science Foundation of Zhejiang Province(Nos.LQ23E030002,LZ23B040001)the National Natural Science Foundation of China(Nos.52303226,21971049)L.Zhan acknowledges the research start-up fund from Hangzhou Normal University(4095C50222204002).
文摘Organic photovoltaics(OPVs)have achieved remarkable progress,with laboratory-scale single-junction devices now demonstrating power conversion efficiencies(PCEs)exceeding 20%.However,these efficiencies are highly dependent on the thickness of the photoactive layer,which is typically around 100 nm.This sensitivity poses a challenge for industrial-scale fabrication.Achieving high PCEs in thick-film OPVs is therefore essential.This review systematically examines recent advancements in thick-film OPVs,focusing on the fundamental mechanisms that lead to efficiency loss and strategies to enhance performance.We provide a comprehensive analysis spanning the complete photovoltaic process chain:from initial exciton generation and diffusion dynamics,through dissociation mechanisms,to subsequent charge-carrier transport,balance optimization,and final collection efficiency.Particular emphasis is placed on cutting-edge solutions in molecular engineering and device architecture optimization.By synthesizing these interdisciplinary approaches and investigating the potential contributions in stability,cost,and machine learning aspects,this work establishes comprehensive guidelines for designing high-performance OPVs devices with minimal thickness dependence,ultimately aiming to bridge the gap between laboratory achievements and industrial manufacturing requirements.
基金supported by the National Natural Science Foundation of China(Nos.22205058,22105064,52122308)the Funding Plan of Key Scientific Research Projects in Colleges and Universities of Henan Province(No.23A150001)+2 种基金Doctoral Scientific Research Start-up Foundation from Henan University of Technology(No.2021BS024)the Project of Youth Backbone Teachers of Henan University of Technology(No.21421250)the Innovative Funds Plan of Henan University of Technology(No.2022ZKCJ01)。
文摘Carbon dots(CDs),due to their low cost,high stability,and high luminous efficiency,have emerged as an excellent material for the emissive layer in next-generation electroluminescent light-emitting diodes(ELEDs).However,improving the efficiency of fluorescent CDs-based ELEDs remains challenging,primarily because it is difficult to utilize triplet excitons in the electroluminescence process.Therefore,enhancing the exciton utilization efficiency of CDs during electroluminescence is crucial.Based on this,we exploited the characteristic large exciton binding energy commonly found in CDs to develop exciton-emitting CDs.These CDs facilitate the radiative recombination of excitons during electroluminescence,thereby improving the electroluminescent efficiency.By rationally selecting precursors,we developed high quantum efficiency CDs and subsequently constructed CDs-based ELEDs.The blue-light device exhibited an external quantum efficiency of over 4%.This study introduces a novel design concept for CDs,providing a new strategy for developing high-performance blue ELEDs based on CDs.
基金supported by the National Natural Science Foundation of China(Grant Nos.12234011 and 12374053)the National Key Research and Development Program of China(Grant No.2024YFA1409100)。
文摘We investigate electronic structures and excitonic properties of monolayer SiP_(2)within the framework of firstprinciples GW plus Bethe-Salpeter equation(GW-BSE)calculations.Within the G_(0)W_(0)approximation,monolayer SiP_(2)is identified as a direct-gap semiconductor with an electronic gap of 3.14 e V,and the excitons exhibit a hybrid-dimensional character similar to that of the bulk counterpart.The optical absorption spectra reveal pronounced excitonic effects with strong anisotropy:the first bright exciton has a binding energy of 840 meV under x-polarized light,compared with 450 meV under y-polarized light.We further analyze the symmetry origins of the polarization-dependent optical selection rules through group theory.This binding energy difference arises from the intrinsic nature of the excitons:flat-band excitons under x-polarized light and conventional excitons localized at a single k point under y-polarized light.Our work enhances the understanding of excitonic behavior in monolayer SiP_(2)and highlights its potential for polarization-sensitive and directionally tunable optoelectronic applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.92263107,U23A20570,52221001,62090035,and 52022029)the Hunan Provincial Natural Science Foundation of China(Grant No.2024RC1034)。
文摘Understanding interlayer charge transfer is crucial for elucidating interface interactions in heterostructures.As the layer number can significantly influence the interface coupling and band alignment,the charge transfer behaviors can be largely regulated.Here,we constructed two-dimensional(2D)heterostructures consisting of monolayer WS_(2)and few-layer InSe to investigate the impact of InSe thickness on exciton dynamics.We performed photoluminescence(PL)spectroscopy and lifetime measurements on pristine few-layer InSe and the heterostructures with different InSe thicknesses.For pristine InSe layers,we found a non-monotonic layer dependence on PL lifetime,which can be attributed to the interplay between the indirect-to-direct bandgap transition and surface recombination effects.For heterostructures,we demonstrated that the type I band alignment of the heterostructure facilitates electron and hole transfer from monolayer WS_(2)to InSe.As the InSe layer number increases,the reduction in conduction band minimum(CBM)enhances the driving force for charge transfer,thereby improving the transfer efficiency.Furthermore,we fabricated and characterized a WS_(2)/InSe optoelectronic device.By analyzing bias voltage dependent PL spectra,we further demonstrated that the trions in WS_(2)within the heterostructure are positively charged(X^(+)),and their emission intensity can be efficiently modulated by applying different biases.This study not only reveals the layer-dependent characteristics of band alignment and interlayer charge transfer in heterostructures but also provides valuable insights for the applications of 2D semiconductors in optoelectronic devices.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2023YFA1406400 and 2020YFA0308800)the National Natural Science Foundation of China(Grant No.12474064)。
文摘The excitonic insulator(EI)is a more than 60-year-old theoretical proposal that is still elusive.It is a purely quantum phenomenon involving the spontaneous generation of excitons in quantum mechanics and the spontaneous condensation of excitons in quantum statistics.At this point,the excitons represent the ground state rather than the conventional excited state.Thus,the scarcity of candidate materials is a key factor contributing to the lack of recognized EI to date.In this review,we begin with the birth of EI,presenting the current state of the field and the main challenges it faces.We then focus on recent advances in the discovery and design of EIs based on the first-principles Bethe-Salpeter scheme,in particular the dark-exciton rule guided screening of materials.It not only opens up new avenues for realizing excitonic instability in direct-gap and wide-gap semiconductors,but also leads to the discovery of novel quantum states of matter such as half-EIs and spin-triplet EIs.Finally,we will look ahead to possible research pathways leading to the first recognized EI,both theoretically and computationally.
基金support by the National Natural Sci-ence Foundation of China(Grant No.12274477)the De-partment of Science and Technology of Guangdong Provincein China(Grant No.2019QN01X061)。
文摘In moiré-patterned van der Waals structures of transition metal dichalcogenides,correlated insulators can form under integer and fractional fillings,whose transport properties are governed by various quasiparticle excitations including holons,doublons and interlayer exciton insulators.Here we theoretically investigate the nearest-neighbor inter-site hoppings of holons and interlayer exciton insulators.Our analysis indicates that these hopping strengths are significantly enhanced compared to that of a single carrier.The underlying mechanism can be attributed to the strong Coulomb interaction between carriers at different sites.For the interlayer exciton insulator consisting of a holon and a carrier in different layers,we have also obtained its effective Bohr radius and energy splitting between the ground and the first-excited states.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174285 and 12474315)support from the National Natural Science Foundation of China(Grant No.62375200)+2 种基金support from the National Natural Science Foundation of China(Grant No.12504372)the China Postdoctoral Science Foundation-Tianjin Joint Support Program(Grant No.2025T003TJ)support from the National Natural Science Foundation of China(Grant No.12404424)。
文摘Two-dimensional(2D)transition-metal dichalcogenide(TMD)monolayers based on become a promising platform to study photonics and optoelectronics.Electrically controlling the excitonic properties of TMD monolayers can be realized in different devices.In this work,we realize the strong coupling between the excitons of WS_(2)monolayers and a photonic cavity mode in a liquid crystal microcavity.The formed exciton polaritons can be electrically tuned by applying voltage to the microcavity.Our work offers a way to study exciton-polariton manipulation based on TMD monolayers by electrical methods at room temperature.
基金the National Natural Science Foundation of China(No.62075115,62335013,22275065,52073116)the National Key R&D Program of China(No.2022YFB4600400)the Natural Science Foundation of Jilin Province(20240101003JJ)for their financial support.
文摘Efficient exciton transport over long distances is crucial for organic optoelectronics.Despite efforts to improve the transport properties of organic semiconductors,the limited exciton diffusion remains a significant obstacle for light-harvesting applications.In this study,we observe phenomena where exciton transport is significantly enhanced by light irradiation in the organic molecular crystal of 2,2'-(2,5-bis(2,2-diphenylvinyl)-1,4-phenylene)dinaphthalene(BDVPN).The exciton transport in this material is improved,as evidenced by the increased diffusion coefficient from 10^(−3) cm^(2)·s^(−1) to over 1 cm^(2)·s^(−1) and a prolonged diffusion length from less than 50 nm to nearly 700 nm characterized by time-resolved photoluminescence microscopy(TPLM).Additionally,we confirmed the enhancement of charge transport capability under irradiation as additional evidence of improved transport properties of the material.These intriguing phenomena may be associated with the material’s twisted molecular conformation and rotatable single bonds,which facilitate light-induced structural alterations conducive to efficient transport properties.Our work provides a novel insight into developing organic semiconductors with efficient exciton transport.
基金Project supported by the National Natural Science Foundation Fund for Distinguished Young Scholars(Grant No.52025022)the National Natural Science Foundation of China(Grant Nos.62574038,12474421,62275045,and 12074060)+1 种基金the National Key R&D Program of China(Grant No.2023YFB3610200)the Fund from Jilin Province(Grant Nos.JJKH20241413KJ and 20240601049RC)。
文摘Two-dimensional(2D)transition metal dichalcogenides(TMDs),endowed with exceptional light-matter interaction strength,have become a pivotal platform in advanced optoelectronics,enabling atomically precise control of excitonic phenomena and offering transformative potential for engineering next-generation optoelectronic devices.In contrast to the narrowband absorption characteristics of conventional band-edge excitons,which are limited by the bandgap energy,highenergy excitons not only demonstrate broad momentum matching capability in the ultraviolet regime due to band nesting effects,but also exhibit distinct absorption peak signatures owing to robust excitonic stabilization under 2D confinement.These unique photophysical properties have established such systems as a prominent research frontier in contemporary exciton physics.This review primarily outlines the distinctive physical characteristics of high-energy excitons in TMDs from the perspectives of band structure,excitonic characteristics,and optical properties.Subsequently,we systematically delineate cutting-edge developments in TMD-based photonic devices exploiting high-energy excitonic band-nesting phenomena,with dedicated emphasis on the strategic engineering of nanoscale heterostructures for tailored optoelectronic functionality.Finally,the discussion concludes with an examination of the challenges associated with the design of high-energy exciton devices and their potential future applications.
基金funded by the National Key Research and Development Program of China(Grant No.2022YFA1405100)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB43000000)。
文摘Transition metal dichalcogenide(TMDC)monolayers provide an ideal platform for exciton and valley-spintronics exploration due to their unique properties.Integrating TMDC monolayers with conventional semiconductors allows for harnessing the unique properties of both materials.This strategy holds great promise for the development of advanced optoelectronics and spintronic devices.In this work,we investigated exciton and valley dynamics in WSe_(2)/Ga As heterostructure by employing the femtosecond pump-probe ultrafast spectroscopy.Facilitated by the charge transfer within the heterostructure,it was found that the exciton of WSe_(2)exhibited much longer lifetime of nanosecond than that of the WSe_(2)monolayer counterpart.Especially,a significantly long valley lifetime up to~2.7 ns was observed for trions of WSe_(2)in the heterostructure even under the off-resonant excitation,which is found to be associated with the resident electrons accumulated at the interface resulting from the charge transfer and resultant interfacial electric field.Our results provide fundamental references for conventional semiconductor-integrated TMDC heterostructures that have great potential for designing novel optoelectronic and spintronic devices.
文摘Correction to:Nano-Micro Letters(2026)18:10.https://doi.org/10.1007/s40820-025-01852-8 Following publication of the original article[1],the authors reported that the last author’s name was inadvertently misspelled.The published version showed“Hongzhen Chen”,whereas the correct spelling should be“Hongzheng Chen”.The correct author name has been provided in this Correction,and the original article[1]has been corrected.
基金supported by the Natural Science Foundation of China(22408278,22275139,21971190,U21A2077)the Key Project of Natural Science Foundation of Tianjin City(Contract No.22JCZDJC00510)Key Laboratory of Functional Inorganic Material Chemistry(Heilongjiang University),Ministry of Education。
文摘Solar-driven hydrogen peroxide(H_(2)O_(2))production offers a sustainable and environmentally friendly alternative to the traditional anthraquinone oxidation method.Conjugated polymers(CPs)are emerging as promising photocatalysts for H_(2)O_(2)production due to their unique electronic,optical properties,and tunable structures.However,the high exciton binding energy of CPs hinders efficient exciton dissociation and charge separation,limiting their photocatalytic performance.In this work,we synthesized scandium(Sc)atoms decorated CPs with enhanced ordered stacking and crystallinity by introducing benzaldehyde as an end-capping reagent.The strong interaction between charged Sc atoms and electrons facilitates exciton dissociation and improves charge transfer capability.Furthermore,the Lewis acidic nature of Sc atoms promotes oxygen adsorption and enhances the stabilization of superoxide anion intermediate(·O_(2)^(-)).As a result,the as-synthesized photocatalysts exhibit a high H_(2)O_(2)production rate of 18μmol h^(-1)in pure water,which is three times that of pristine CPs,This work provides valuable insights into the design of organic polymer photocatalysts for various photocatalytic reactions.
基金supported by the National Natural Science Foundation of China(Nos.22033006,22173074,22473091, 92372105).
文摘Focusing on the mechanism of interfa-cial exciton dissociation in edge-on stacked ZnPc-F_(8)ZnPc aggregate,we employ the fragment particle-hole densities(FPHD)method to con-struct the Hamiltonian of diabatic states and use the non-Markovian stochastic Schrödinger equation(NMSSE)to simulate the photo-in-duced dynamics processes.The re-sults show that aggregation effects have a significant impact on the interfacial exciton dissociation process.After photo-excita-tion,the excitons first preferentially delocalize and perform the charge transfer(CT)states in the pure ZnPc or F_(8)ZnPc aggregates within 100 fs.These‘intramolecular’CT states can easi-ly evolve into interfacial CT states by hopping electrons and holes in the intramolecular CT states across the interface.Compared with these exciton dissociation processes,the direct ex-citon dissociation into interfacial CT state is relatively slow due to the small electronic cou-pling and vibrational coherence between the locally excited state and the interfacial CT state.As the temperature rises and the vibronic coherence weakens,the direct dissociation rates are significantly enhanced.This investigation provides valuable insights for the design and opti-mization of high-performance organic photovoltaic devices.
基金supported by the National Natural Science Foundation of China(Grant No.12434011 obtained by Q X)the China Postdoctoral Science Foundation(Grant No.Y24PJ2425214 obtained by L T).
文摘Supersolidity is a counterintuitive quantum phase of matter where the long-range spatial order of a solid coexists with the frictionless flow characteristic of a superfluid.Recently,evidence of supersolidity has been demonstrated in polariton condensates in III-V photonic crystal microcavities by condensing into a topological bound state in the continuum,offering a new light-matter hybrid platform for exploring such quantum phase.In this work,we propose a theoretical scheme for realizing room-temperature supersolidity based on halide perovskite exciton polaritons operating in the optical parametric oscillation regime.By employing a waveguide microcavity geometry,we confine polariton scattering direction in reciprocal space,enabling controlled momentum selection.Leveraging the intrinsic nonlinear interactions among polaritons,we theoretically demonstrate the spontaneous breaking of both continuous translational symmetry and global phase symmetry,i.e.,the evidence of supersolidity.Furthermore,we identify a tunable phase transition sequence in our system:from a Bose-Einstein condensate to a supersolid phase,and ultimately to an insulating phase,as the nonlinear interaction strength increases.
基金Project supported by the National Key R&D Program of China(Grant Nos.2022YFA1402400 and 2022YFA1405400)the National Natural Science Foundation of China(Grant Nos.11934011 and 12274365)+3 种基金Zhejiang Provincial Natural Science Foundation of China(Grant No.LR24A040001)Open project of Key Laboratory of Artificial Structures and Quantum Control(Ministry of Education)of Shanghai Jiao Tong Universitysupport from the JSPS KAKENHI(Grant Nos.20H00354 and 23H02052)World Premier International Research Center Initiative(WPI),MEXT,Japan。
文摘Semiconductor moirésuperlattices provide great platforms for exploring exotic collective excitations.Optical Stark effect,a shift of the electronic transition in the presence of a light field,provides an ultrafast and coherent method of manipulating matter states,which,however,has not been demonstrated in moirématerials.Here,we report the valleyselective optical Stark effect of moiréexcitons in the WSe_(2)/WS_(2)superlattice by using transient reflection spectroscopy.Prominent valley-selective energy shifts up to 7.8 meV have been observed for moiréexcitons,corresponding to pseudomagnetic fields as large as 34 T.Our results provide a route to coherently manipulate exotic states in moirésuperlattices.
基金supported by the National Key Research&Development Program of China(Grant Nos.2022YFA1403500 and 2021YFA1400500)the National Science Foundation of China(Grant Nos.62321004,12234001,and 12474215)+1 种基金supported by New Cornerstone Science Foundationa fellowship and a CRF award from the Research Grants Council of the Hong Kong Special Administrative Region,China(Grant Nos.HKUST SRFS2324-6S01 and C7037-22GF)。
文摘Electron-hole interactions play a crucial role in determining the optoelectronic properties of materials,and in lowdimensional systems this is especially true due to the decrease of screening.In this review,we focus on one unique quantum phase induced by the electron-hole interaction in two-dimensional systems,known as“exciton insulators”(EIs).Although this phase of matter has been studied for more than half a century,suitable platforms for its stable realization remain scarce.We provide an overview of the strategies to realize EIs in accessible materials and structures,along with a discussion on some unique properties of EIs stemming from the band structures of these materials.Additionally,signatures in experiments to distinguish EIs are discussed.
基金supported by the National Natural Science Foundation of China(Nos.22002107,21905202,22179093)。
文摘Carbon nitride,a typical low-dimensional conjugated polymer photocatalyst,features a high exciton binding energy due to the weak dielectric screening and the strong Coulombic attraction of photogenerated electrons and holes.The reduction of the exciton binding energy of carbon nitride to promote the conversion from excitons into free carriers is the first priority for the improvement of charge-transfer-dependent photocatalytic reaction activity.In this paper,by introducing a variety of polar metal cations to carbon nitride,it is demonstrated that the charge distribution of the heptazine ring can be improved by ion polarization,which effectively promotes the dissociation of excitons into electrons and holes.The sodium ion shows the best modification effect,which enhances the rate of both photocatalytic hydrogen and hydrogen peroxide production by about 50%.Characterization shows that the introduction of strongly polar metal cations contributes to the reduction of the exciton dissociation energy of carbon nitride.This study provides a new perspective and a convenient method for the exciton modulation engineering of low-dimensional photocatalysts.
基金supported by the National Natural Science Foundation of China(No.22173090 and No.91950207)the Innovation Program for Quantum Science and Technology(No.2021ZD0303303)+2 种基金the National Key Research and Development Program of China(No.2016YFA0200602 and No.2018YFA0208702)the Anhui Initiative in Quantum Information Technologies(No.AHY090200)the USTC Key Directions Project Incubation Fund(No.WK2340000106).
文摘We report a mechanistic study of excitonic photoluminescence in predesigned hybrid organic-inorganic perovskite(HOIP)systems,i.e.,(DMAEA)Pb_(2)I_(6),(DMAPA)PbI_(4),(DEAEA)Pb_(2)I_(6),and(DEAPA)_(4)Pb_(5)I_(18),featuring targeted regulation of organic cations.Starting from the prototype DMAEA(i.e.,2-N,N-dimethylamino-l-ethylamine)for(DMAEA)Pb_(2)I_(6),the other three HOIPs differ only in the extensions with CH_(2)group(s)at the“head”or/and“tail”of DMAEA that is an“alkylated ammonia”.Their crystal structures are constructed and structural distortions are evaluated.The steady-state/transient absorption and emission spectroscopic characterizations,combined with the band-structure calculations,are conducted.The two different photoluminescence(PL)mechanisms are identified,i.e.,PL emissions dominated by free excitons for(DMAPA)PbI_(4)and by self-trapped excitons for(DMAEA)Pb_(2)I_(6),(DEAEA)Pb_(2)I_(6),and(DEAPA)_(4)Pb_(5)I_(18).The self-trapped excitonic effect involved in the latter three HOIPs is quantitatively analyzed.This work would be of guiding value for the design of HOIP systems based on organic-cation engineering,beneficial for the pertinent performance optimization in light-emitting applications.
