Light-harvesters with long-lived excited states are desired for efficient solar energy conversion systems. Many solar-to-fuel conversion reactions, such as H2 evolution and CO2 reduction, require multiple sequential e...Light-harvesters with long-lived excited states are desired for efficient solar energy conversion systems. Many solar-to-fuel conversion reactions, such as H2 evolution and CO2 reduction, require multiple sequential electron transfer processes, which leads to a complicated situation that excited states involves not only excitons （electron-hole pairs） but also multi-excitons and charged excitons. While long-lived excitons can be obtained in various systems （e.g., semiconductor nanocrystals）, multi-excitons and charged excitons are typically shorted-lived due to nonradiative Auger recombination pathways whereby the recombination energy of an exciton is quickly transferred to the third carrier on a few to hundreds of picoseconds timescale. In this work, we report a study of excitons, trions （an exciton plus an additional charge）, and biexcitons in CdSe/CdTe colloidal quantum wells or nanoplatelets. The type- II band alignment effectively separates electrons and holes in space, leading to a single exciton lifetime of 340 ns which is -2 order of magnitudes longer than that in plane CdSe nanoplatelets. More importantly, the electron-hole separation also dramatically slows down Auger decay, giving rise to a trion lifetime of 70 ns and a biexciton lifetime of 11 ns, among the longest values ever reported for colloidal nanocrystals. The long-lived exciton, trion, and biexciton states, combined with the intrinsically strong light-absorption capability of two-dimensional systems, enable the CdSe/CdTe type-II nanoplatelets as promising light harvesters for efficient solar-to-fuel conversion reactions.展开更多
Interface engineering in atomically thin transition metal dichalcogenides(TMDs)is becoming an important and powerful technique to alter their properties,enabling new optoelectronic applications and quantum devices.Int...Interface engineering in atomically thin transition metal dichalcogenides(TMDs)is becoming an important and powerful technique to alter their properties,enabling new optoelectronic applications and quantum devices.Interface engineering in a monolayer WSe_(2)sample via introduction of high-density edges of standing structured graphene nanosheets(GNs)is realized.A strong photoluminescence(PL)emission peak from intravalley and intervalley trions at about 750 nm is observed at the room temperature,which indicated the heavily p-type doping of the monolayer WSe_(2)/thin graphene nanosheet-embedded carbon(TGNEC)film heterostructure.We also successfully triggered the emission of biexcitons(excited state biexciton)in a monolayer WSe_(2),via the electron trapping centers of edge quantum wells of a TGNEC film.The PL emission of a monolayer WSe_(2)/GNEC film is quenched by capturing the photoexcited electrons to reduce the electron-hole recombination rate.This study can be an important benchmark for the extensive understanding of light–matter interaction in TMDs,and their dynamics.展开更多
The transition from the biexciton to the exciton can turn over the direction of the electric dipole of a polymericmolecule. This turning-over action combined with the photoinduced polarization reversion can be used as...The transition from the biexciton to the exciton can turn over the direction of the electric dipole of a polymericmolecule. This turning-over action combined with the photoinduced polarization reversion can be used as a switch. Theswitching speed is governed by the relaxation time of the turning-over process, which can be determined by a dynamicalsimulation.展开更多
It has been known that the static polarizability of a polymer chain with a biexciton is negative. In order to understand this peculiar fact, this paper studies the dynamical process of the charge transfer in the polym...It has been known that the static polarizability of a polymer chain with a biexciton is negative. In order to understand this peculiar fact, this paper studies the dynamical process of the charge transfer in the polymer chain induced by an external electric held E during forming the biexciton. The time dependence of the charge distribution in the chain reveals that the charge transfer is backward: the positive charge shifts in the opposite direction of the external electric field. Such a backward charge transfer (BCT) produces an opposite dipole, which makes the polarization negative. The effect of electron interaction on the BCT is illustrated.展开更多
We theoretically analyze the steady state emission spectrum and transient temporal dynamics in a coupled biexciton quantum dot（QD）–cavity system. For steady state, a phonon-assisted biexciton–exciton cascade model...We theoretically analyze the steady state emission spectrum and transient temporal dynamics in a coupled biexciton quantum dot（QD）–cavity system. For steady state, a phonon-assisted biexciton–exciton cascade model under continuous wave（CW） excitation is presented to explain the asymmetric QD–cavity emission spectrum intensities（intensities of cavity,exciton, and biexciton emission peak） in off-resonance condition. Results demonstrate that the electron–phonon process is crucial to the asymmetry of emission spectrum intensity. Moreover the transient characteristics of the biexciton–exciton cascade system under pulse excitation show abundant nonlinear temporal dynamic behaviors, including complicated oscillations which are caused by the four-level structure of QD model. We also reveal that under off-resonance condition the cavity outputs are slightly reduced due to the electron–phonon interaction.展开更多
The effect of interchain coupling on the formation and the stability of a biexciton is studied in poly （p-phenylene vinylene） chains in the framework of the tight-binding approach. We obtain an intrachain exciton an...The effect of interchain coupling on the formation and the stability of a biexciton is studied in poly （p-phenylene vinylene） chains in the framework of the tight-binding approach. We obtain an intrachain exciton and biexciton as well as an interchain exciton and biexciton through a double-photon excitation.It is found that a biexciton is energetically favourable to two single excitons even when there exists an interchain coupling.There is a turnover value t⊥c of the interchain coupling for the formation of a biexciton,beyond which two excitons are combined into one biexciton.The binding energy of a biexciton is calculated to decrease with the increase of interchain coupling,which indicates that a biexciton is relatively stable in polymers with a weak interchain coupling.The conclusion is consistent with the experimental observations.In addition,a suggestion about how to improve the yielding efficiency or the formation of biexcitons in actual applications is given.展开更多
A double cascade-type four-level multiple-quantum-well-based exciton-biexciton transitions are proposed. The study is carried out on a 4.8-rim ZnSe single-quantum well which is embedded into ZnMgSSe cladding layers an...A double cascade-type four-level multiple-quantum-well-based exciton-biexciton transitions are proposed. The study is carried out on a 4.8-rim ZnSe single-quantum well which is embedded into ZnMgSSe cladding layers and pseudomor- phically grown by molecular beam epitaxy on a （0 0 1） GaAs substrate. It is displayed that the exciton spin relaxation and relative phases between applied fields can influence the transient and steady-state behaviors of absorption, dispersion, and group velocity of two weak probe and signal fields. Also, transient behaviors of electron population of different levels are discussed. It is found that the probe or signal amplification occurs in the absence of population inversion.展开更多
We report the observed photon bunching statistics of biexciton cascade emission at zero time delay in single quantum dots by second-order correlation function g（2） （T） measurements under continuous wave excitation...We report the observed photon bunching statistics of biexciton cascade emission at zero time delay in single quantum dots by second-order correlation function g（2） （T） measurements under continuous wave excitation. It is found that the bunching phenomenon is independent of the biexciton binding energy when it varies from 0.59 meV to nearly zero. The photon bunching takes place when the exeiton photon is not spectrally distinguishable from the biexciton photon, and either of them can trigger the %tart＇ in a Hanbury-Brown and Twiss setup. However, if the exciton energy is spectrally distinguishable from the biexciton, the photon statistics will become asymmetric and a cross-bunching lineshape can be obtained. The theoretical calculations based on a model of three-level rate-equation analysis are consistent with the result of g（2）（τ） correlation function measurements.展开更多
Lead halide perovskite quantum dots(QDs)suffer from frequent batch-to-batch inconsistencies and poor reproducibility,resulting in serious non-radiative defect-assisted recombination and Auger recombination.To overcome...Lead halide perovskite quantum dots(QDs)suffer from frequent batch-to-batch inconsistencies and poor reproducibility,resulting in serious non-radiative defect-assisted recombination and Auger recombination.To overcome these challenges,in this study,CsPbBr3 QDs were prepared by designing a novel cesium precursor recipe that involved a combination of dual-functional acetate(AcO-)and 2-hexyldecanoic acid(2-HA)as short--branched-chain ligand:first,AcO aided in significantly improving the complete conversion degree of cesium salt,enhancing the purity of the cesium precursor from 70.26%to 98.59%with a low relative standard deviation of size distribution and photoluminescence quantum yield(9.02 and 0.82%,respectively)by decreasing the formation of by-products during the reaction,which leads to enhanced homogeneity and reproducibility,especially at room-temperature.Second,AcO can act as a surface ligand to passivate the dangling surface bonds.Furthermore,compared to oleic acid,2-HA exhibited a stronger binding affinity toward the QDs,further passivated the surface defects,and effectively suppressed biexciton Auger recombination,thereby improving the spontaneous emission rate of the QDs.Consequently,the QDs prepared using this new recipe exhibited a uniform size distribution,a green emission peak at 512 nm,a high photoluminescence quantum yield of 99%with excellent stability,and a narrow emission linewidth of 22 nm.In particular,the optimized QDs exhibited enhanced amplified spontaneous-2 emission(ASE)performance,while the ASE threshold of treated QDs reduced by 70%from 1.8μJ·cm to 0.54μJ·cm-2.展开更多
Auger recombination has been a long?standing obstacle to many prospective applications of colloidal quantum dots (QDs) ranging from lasing, light-emitting diodes to bio-labeling. As such, understanding the physical un...Auger recombination has been a long?standing obstacle to many prospective applications of colloidal quantum dots (QDs) ranging from lasing, light-emitting diodes to bio-labeling. As such, understanding the physical underpinnings and scaling laws for Auger recombination is essential to these applications. Previous studies of biexciton Auger recombination in various QDs established a universal scaling of biexciton lifetime (rxx) with QD volume (V):τxx =γV. However, recent measurements on perovskite nanocrystals (NCs), an emerging class of enablers for light harvest!ng and emitting applications, showed significant deviations from this universal scaling law, likely because the measured NCs are weakly-confined and also have relatively broad size-distributions. Here we study biexciton Auger recombination in mono-dispersed (size distributions within 1.7%—9.0%), quantunvconfined CsPbBr3 NCs (with confinement energy up to 410 meV) synthesized using a latest approach based on thermodynamic equilibrium control. Our measurements clearly reproduce the volume-scaling of τxx in confined CsPbBb QDs. However, the scaling factor γ(0.085 ± 0.001 ps/nm^3) is one order of magnitude lower than that reported for CdSe and PbSe QDs (1.00 ± 0.05 ps/nm^3), suggest!ng unique mechanisms enhancing Auger recombination rate in perovskite NCs.展开更多
Charge carrier dynamics essentially determines the performance of various optoelectronic applications of colloidal semiconductor nanocrystals.Among them,two-dimensional nanoplatelets provide new adjustment freedom for...Charge carrier dynamics essentially determines the performance of various optoelectronic applications of colloidal semiconductor nanocrystals.Among them,two-dimensional nanoplatelets provide new adjustment freedom for their unique core/crown heterostructures.Herein,we demonstrate that by fine-tuning the core size and the lateral quantum confinement,the charge carrier transfer rate from the crown to the core can be varied by one order of magnitude in CdSe/CdSeS core/alloy-crown nanoplatelets.In addition,the transfer can be affected by a carrier blocking mechanism,i.e.,the filled carriers hinder further possible transfer.Furthermore,we found that the biexciton interaction is oppositely affected by quantum confinement and electron delocalization,resulting in a non-monotonic variation of the biexciton binding energy with the emission wavelength.This work provides new observations and insights into the charge carrier transfer dynamics and exciton interactions in colloidal nanoplatelets and will promote their further applications in lasing,display,sensing,etc.展开更多
Here I provide a summary of my group’s research on the photophysics of nanocrystal quantum dots and briefly discuss multipeak luminescence structures related to excitons,trions,and biexcitons in halide perovskite nan...Here I provide a summary of my group’s research on the photophysics of nanocrystal quantum dots and briefly discuss multipeak luminescence structures related to excitons,trions,and biexcitons in halide perovskite nanocrystals.展开更多
Colloidal semiconductor quantum dots(QDs)exhibit broadband light absorption,continuously tunable narrowband emission,and high photoluminescence quantum yields.As such,they represent promising materials for use in ligh...Colloidal semiconductor quantum dots(QDs)exhibit broadband light absorption,continuously tunable narrowband emission,and high photoluminescence quantum yields.As such,they represent promising materials for use in light-emitting diodes,solar cells,detectors,and lasers.Single-QD spectroscopy can remove the ensemble averaging to reveal the diverse optical properties and exciton dynamics of QD materials at the single-particle level.The results of relevant research can serve as guidelines for materials science community in tailoring the synthesis of QDs to develop novel applications.This paper reviews recent progress in exciton dynamics revealed by single-QD spectroscopy,focusing on the exciton and multi-exciton dynamics of single colloidal CdSe-based QDs and perovskite QDs.Finally,potential future directions for single-QD spectroscopy and exciton dynamics are briefly considered.展开更多
文摘Light-harvesters with long-lived excited states are desired for efficient solar energy conversion systems. Many solar-to-fuel conversion reactions, such as H2 evolution and CO2 reduction, require multiple sequential electron transfer processes, which leads to a complicated situation that excited states involves not only excitons （electron-hole pairs） but also multi-excitons and charged excitons. While long-lived excitons can be obtained in various systems （e.g., semiconductor nanocrystals）, multi-excitons and charged excitons are typically shorted-lived due to nonradiative Auger recombination pathways whereby the recombination energy of an exciton is quickly transferred to the third carrier on a few to hundreds of picoseconds timescale. In this work, we report a study of excitons, trions （an exciton plus an additional charge）, and biexcitons in CdSe/CdTe colloidal quantum wells or nanoplatelets. The type- II band alignment effectively separates electrons and holes in space, leading to a single exciton lifetime of 340 ns which is -2 order of magnitudes longer than that in plane CdSe nanoplatelets. More importantly, the electron-hole separation also dramatically slows down Auger decay, giving rise to a trion lifetime of 70 ns and a biexciton lifetime of 11 ns, among the longest values ever reported for colloidal nanocrystals. The long-lived exciton, trion, and biexciton states, combined with the intrinsically strong light-absorption capability of two-dimensional systems, enable the CdSe/CdTe type-II nanoplatelets as promising light harvesters for efficient solar-to-fuel conversion reactions.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(Nos.62104155,52275565,52005343,and 62204117)of Chinathe Natural Science Foundation of Guangdong Province(No.2022A1515011667)+1 种基金the financial support from Jiangsu Province Science Foundation for Youths(No.BK20210275)Guangdong Kangyi Special Fund(No.2020KZDZX1173).
文摘Interface engineering in atomically thin transition metal dichalcogenides(TMDs)is becoming an important and powerful technique to alter their properties,enabling new optoelectronic applications and quantum devices.Interface engineering in a monolayer WSe_(2)sample via introduction of high-density edges of standing structured graphene nanosheets(GNs)is realized.A strong photoluminescence(PL)emission peak from intravalley and intervalley trions at about 750 nm is observed at the room temperature,which indicated the heavily p-type doping of the monolayer WSe_(2)/thin graphene nanosheet-embedded carbon(TGNEC)film heterostructure.We also successfully triggered the emission of biexcitons(excited state biexciton)in a monolayer WSe_(2),via the electron trapping centers of edge quantum wells of a TGNEC film.The PL emission of a monolayer WSe_(2)/GNEC film is quenched by capturing the photoexcited electrons to reduce the electron-hole recombination rate.This study can be an important benchmark for the extensive understanding of light–matter interaction in TMDs,and their dynamics.
基金This work was supported by the National Natural Science Foundation of China (Grants 19874014 and 20074007), Doctoral Fund for Universities and "863" Projects.
文摘The transition from the biexciton to the exciton can turn over the direction of the electric dipole of a polymericmolecule. This turning-over action combined with the photoinduced polarization reversion can be used as a switch. Theswitching speed is governed by the relaxation time of the turning-over process, which can be determined by a dynamicalsimulation.
文摘It has been known that the static polarizability of a polymer chain with a biexciton is negative. In order to understand this peculiar fact, this paper studies the dynamical process of the charge transfer in the polymer chain induced by an external electric held E during forming the biexciton. The time dependence of the charge distribution in the chain reveals that the charge transfer is backward: the positive charge shifts in the opposite direction of the external electric field. Such a backward charge transfer (BCT) produces an opposite dipole, which makes the polarization negative. The effect of electron interaction on the BCT is illustrated.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61275201 and 61372037)the Beijing Municipal Excellent Ph.D. Thesis Guidance Foundation(Grant No.20131001301)the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications),China
文摘We theoretically analyze the steady state emission spectrum and transient temporal dynamics in a coupled biexciton quantum dot（QD）–cavity system. For steady state, a phonon-assisted biexciton–exciton cascade model under continuous wave（CW） excitation is presented to explain the asymmetric QD–cavity emission spectrum intensities（intensities of cavity,exciton, and biexciton emission peak） in off-resonance condition. Results demonstrate that the electron–phonon process is crucial to the asymmetry of emission spectrum intensity. Moreover the transient characteristics of the biexciton–exciton cascade system under pulse excitation show abundant nonlinear temporal dynamic behaviors, including complicated oscillations which are caused by the four-level structure of QD model. We also reveal that under off-resonance condition the cavity outputs are slightly reduced due to the electron–phonon interaction.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10804062 and 10874100)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant Nos 200804221005 and 20070422058)China Postdoctoral Science Foundation funded project (Grant No 20080431171)
文摘The effect of interchain coupling on the formation and the stability of a biexciton is studied in poly （p-phenylene vinylene） chains in the framework of the tight-binding approach. We obtain an intrachain exciton and biexciton as well as an interchain exciton and biexciton through a double-photon excitation.It is found that a biexciton is energetically favourable to two single excitons even when there exists an interchain coupling.There is a turnover value t⊥c of the interchain coupling for the formation of a biexciton,beyond which two excitons are combined into one biexciton.The binding energy of a biexciton is calculated to decrease with the increase of interchain coupling,which indicates that a biexciton is relatively stable in polymers with a weak interchain coupling.The conclusion is consistent with the experimental observations.In addition,a suggestion about how to improve the yielding efficiency or the formation of biexcitons in actual applications is given.
文摘A double cascade-type four-level multiple-quantum-well-based exciton-biexciton transitions are proposed. The study is carried out on a 4.8-rim ZnSe single-quantum well which is embedded into ZnMgSSe cladding layers and pseudomor- phically grown by molecular beam epitaxy on a （0 0 1） GaAs substrate. It is displayed that the exciton spin relaxation and relative phases between applied fields can influence the transient and steady-state behaviors of absorption, dispersion, and group velocity of two weak probe and signal fields. Also, transient behaviors of electron population of different levels are discussed. It is found that the probe or signal amplification occurs in the absence of population inversion.
基金Supported by the National Key Basic Research Program of China under Grant No 2013CB922304the National Natural Science Foundation of China under Grant Nos 11474275 and 11464034
文摘We report the observed photon bunching statistics of biexciton cascade emission at zero time delay in single quantum dots by second-order correlation function g（2） （T） measurements under continuous wave excitation. It is found that the bunching phenomenon is independent of the biexciton binding energy when it varies from 0.59 meV to nearly zero. The photon bunching takes place when the exeiton photon is not spectrally distinguishable from the biexciton photon, and either of them can trigger the %tart＇ in a Hanbury-Brown and Twiss setup. However, if the exciton energy is spectrally distinguishable from the biexciton, the photon statistics will become asymmetric and a cross-bunching lineshape can be obtained. The theoretical calculations based on a model of three-level rate-equation analysis are consistent with the result of g（2）（τ） correlation function measurements.
基金financially supported by the National Natural Science Foundation of China(No.52302171)Shandong Provincial Natural Science Foundation,China(ZR2023QF005)+2 种基金Heilongjiang Provincial Natural Science Foundation of China(LH2023F026,LH2020A007,and LH2020F027)New Era Longjiang Excellent Doctoral Discovery Project(LJYXL2022-003),Teaching Reform Research Project of Harbin Engineering University(79005023/013)Fundamental Research Funds for the Central Universities(3072024XX2606,3072022TS2613,79000012/012).
文摘Lead halide perovskite quantum dots(QDs)suffer from frequent batch-to-batch inconsistencies and poor reproducibility,resulting in serious non-radiative defect-assisted recombination and Auger recombination.To overcome these challenges,in this study,CsPbBr3 QDs were prepared by designing a novel cesium precursor recipe that involved a combination of dual-functional acetate(AcO-)and 2-hexyldecanoic acid(2-HA)as short--branched-chain ligand:first,AcO aided in significantly improving the complete conversion degree of cesium salt,enhancing the purity of the cesium precursor from 70.26%to 98.59%with a low relative standard deviation of size distribution and photoluminescence quantum yield(9.02 and 0.82%,respectively)by decreasing the formation of by-products during the reaction,which leads to enhanced homogeneity and reproducibility,especially at room-temperature.Second,AcO can act as a surface ligand to passivate the dangling surface bonds.Furthermore,compared to oleic acid,2-HA exhibited a stronger binding affinity toward the QDs,further passivated the surface defects,and effectively suppressed biexciton Auger recombination,thereby improving the spontaneous emission rate of the QDs.Consequently,the QDs prepared using this new recipe exhibited a uniform size distribution,a green emission peak at 512 nm,a high photoluminescence quantum yield of 99%with excellent stability,and a narrow emission linewidth of 22 nm.In particular,the optimized QDs exhibited enhanced amplified spontaneous-2 emission(ASE)performance,while the ASE threshold of treated QDs reduced by 70%from 1.8μJ·cm to 0.54μJ·cm-2.
基金We gratefully acknowledge financial supports from the MinistryScience and Technology of China (No. 2018YFA028703)the National Natural Science Foundation of China (No. 21773239).
文摘Auger recombination has been a long?standing obstacle to many prospective applications of colloidal quantum dots (QDs) ranging from lasing, light-emitting diodes to bio-labeling. As such, understanding the physical underpinnings and scaling laws for Auger recombination is essential to these applications. Previous studies of biexciton Auger recombination in various QDs established a universal scaling of biexciton lifetime (rxx) with QD volume (V):τxx =γV. However, recent measurements on perovskite nanocrystals (NCs), an emerging class of enablers for light harvest!ng and emitting applications, showed significant deviations from this universal scaling law, likely because the measured NCs are weakly-confined and also have relatively broad size-distributions. Here we study biexciton Auger recombination in mono-dispersed (size distributions within 1.7%—9.0%), quantunvconfined CsPbBr3 NCs (with confinement energy up to 410 meV) synthesized using a latest approach based on thermodynamic equilibrium control. Our measurements clearly reproduce the volume-scaling of τxx in confined CsPbBb QDs. However, the scaling factor γ(0.085 ± 0.001 ps/nm^3) is one order of magnitude lower than that reported for CdSe and PbSe QDs (1.00 ± 0.05 ps/nm^3), suggest!ng unique mechanisms enhancing Auger recombination rate in perovskite NCs.
基金This work was supported by the National Natural Science Foundation of China(No.61875002)the National Key R&D Program of China(No.2018YFA0306302)+4 种基金the Beijing Natural Science Foundation(No.Z190005)the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices(No.KF202208)The author acknowledges the support of the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)the National Natural Science Foundation of China(Nos.11874130 and 22073022)the support from the DNL Cooperation Fund,CAS(No.DNL202016)of Dalian National Laboratory for Clean Energy。
文摘Charge carrier dynamics essentially determines the performance of various optoelectronic applications of colloidal semiconductor nanocrystals.Among them,two-dimensional nanoplatelets provide new adjustment freedom for their unique core/crown heterostructures.Herein,we demonstrate that by fine-tuning the core size and the lateral quantum confinement,the charge carrier transfer rate from the crown to the core can be varied by one order of magnitude in CdSe/CdSeS core/alloy-crown nanoplatelets.In addition,the transfer can be affected by a carrier blocking mechanism,i.e.,the filled carriers hinder further possible transfer.Furthermore,we found that the biexciton interaction is oppositely affected by quantum confinement and electron delocalization,resulting in a non-monotonic variation of the biexciton binding energy with the emission wavelength.This work provides new observations and insights into the charge carrier transfer dynamics and exciton interactions in colloidal nanoplatelets and will promote their further applications in lasing,display,sensing,etc.
基金support in preparing this manuscript.Part of this work was supported by Core Research for Evolutionary Science and Technology,Japan Science and Technology Agency(JST CREST)(JPMJCR21B4)Grant-in-Aid for Specially promoted Research,Japan Society for the Promotion of Science(JSPS KAKENHI)(JP19H05465).
文摘Here I provide a summary of my group’s research on the photophysics of nanocrystal quantum dots and briefly discuss multipeak luminescence structures related to excitons,trions,and biexcitons in halide perovskite nanocrystals.
基金supported by the National Key Research and Development Program of China(No.2022YFA1404201)the National Natural Science Foundation of China(Nos.62305201,62075120,62075122,62127817,62222509,U22A2091,U23A20380,and 62105193)+6 种基金Program for Changjiang Scholars and Innovative Research Team(No.IRT_17R70)Shanxi Province Science and Technology Major Special Project(No.202201010101005)Fundamental Research Program of Shanxi Province(Nos.202103021223254 and 202203021221121)Graduate Innovation Project in Shanxi Province(No.2023KY460)Shanxi Province Science and Technology Innovation Talent Team(No.202204051001014)Science and Technology Cooperation Project of Shanxi Province(No.202104041101021)Shanxi“1331 Project”,111 projects(No.D18001).
文摘Colloidal semiconductor quantum dots(QDs)exhibit broadband light absorption,continuously tunable narrowband emission,and high photoluminescence quantum yields.As such,they represent promising materials for use in light-emitting diodes,solar cells,detectors,and lasers.Single-QD spectroscopy can remove the ensemble averaging to reveal the diverse optical properties and exciton dynamics of QD materials at the single-particle level.The results of relevant research can serve as guidelines for materials science community in tailoring the synthesis of QDs to develop novel applications.This paper reviews recent progress in exciton dynamics revealed by single-QD spectroscopy,focusing on the exciton and multi-exciton dynamics of single colloidal CdSe-based QDs and perovskite QDs.Finally,potential future directions for single-QD spectroscopy and exciton dynamics are briefly considered.
