We investigate the transfer of phosphorescent energy between co-assembled metallophosphors in crystalline nanostructures [Angew. Chem. Int. Ed. 57 7820(2018) and J. Am. Chem. Soc. 140 4269(2018)]. Neither Dexter's...We investigate the transfer of phosphorescent energy between co-assembled metallophosphors in crystalline nanostructures [Angew. Chem. Int. Ed. 57 7820(2018) and J. Am. Chem. Soc. 140 4269(2018)]. Neither Dexter's nor Forster's mechanism of resonance energy transfer(RET) could account fully for the observed rates, which exceed 85% with significant temperature dependence. But there exists an alternative pathway on RET mediated by intermediate states of resonantly confined exciton–polaritons. Such a mechanism was used to analyze artificial photosynthesis in organic fluorescents [Phys.Rev. Lett. 122 257402(2019)]. For metallophosphors, the confined modes act as extended states lying between the molecular S_(1) and T_(1) states, offering a bridge for the long-lived T_(1) excitons to migrate from donors to acceptors. Population dynamics with parameters taken entirely based on experiments fits the observed lifetimes of phosphorescence across a broad range of doping and temperature.展开更多
The quest for realizing novel fundamental physical effects and practical applications in ambient conditions has led to tremendous interest in microcavity exciton polaritons working in the strong coupling regime at roo...The quest for realizing novel fundamental physical effects and practical applications in ambient conditions has led to tremendous interest in microcavity exciton polaritons working in the strong coupling regime at room temperature.In the past few decades,a wide range of novel semiconductor systems supporting robust exciton polaritons have emerged,which has led to the realization of various fascinating phenomena and practical applications.This paper aims to review recent theoretical and experimental developments of exciton polaritons operating at room temperature,and includes a comprehensive theoretical background,descriptions of intriguing phenomena observed in various physical systems,as well as accounts of optoelectronic applications.Specifically,an in-depth review of physical systems achieving room temperature exciton polaritons will be presented,including the early development of ZnO and GaN microcavities and other emerging systems such as organics,halide perovskite semiconductors,carbon nanotubes,and transition metal dichalcogenides.Finally,a perspective of outlooking future developments will be elaborated.展开更多
In this paper the bulk exciton polaritons in ternary mixed crystals （TMCs） are investigated in the Born-Huang approximation. The numerical results of the polariton frequencies as functions of the wave-vector and the...In this paper the bulk exciton polaritons in ternary mixed crystals （TMCs） are investigated in the Born-Huang approximation. The numerical results of the polariton frequencies as functions of the wave-vector and the compositions for ternary mixed crystals AlxGa1-xAs, CdxZn1-xSe, and AlxGa1-xN are obtained and discussed. The new dispersion characteristics for exciton-polaritons in TMC systems are found in comparison with binary crystals. The splitting of the two branches of exciton-polariton frequencies varies nonlinearly with the composition of TMCs and has a minimum in the long-wavelength range.展开更多
The low-temperature (T = 2 K) exciton-polariton luminescence (EPL) spectra in the vicinity of the exciton-resonance frequency An=1 for CdS-type crystals have been theoretically and experimentally investigated with all...The low-temperature (T = 2 K) exciton-polariton luminescence (EPL) spectra in the vicinity of the exciton-resonance frequency An=1 for CdS-type crystals have been theoretically and experimentally investigated with allowance for the mechanical exciton decay . The results of the numerical calculations of the partial and interference contributions of the bulk and radiative surface spectral modes to the EPL in the geometry of additional s- and p-polarized waves emitted into vacuum are analyzed. It is shown that the contributions of purely longitudinal excitons and their interference with polaritons of the upper dispersion branch near the longitudinal frequency ωL to the EPL are small (∼10% - 30%);nevertheless, they must be taken into account to obtain quantitative agreement with experimental data. Specifically these contributions are responsible for the formation of an additional line (along with the fundamental AT line) in the case of oblique incidence of radiation.展开更多
The scope of the study is the spectra of low-temperature (T = 2K) photoluminescence of a p-CdTe/n-CdS film heterostructure comprising a monolayer of CdTe microcrystals, where a single microcrystalline particle is typi...The scope of the study is the spectra of low-temperature (T = 2K) photoluminescence of a p-CdTe/n-CdS film heterostructure comprising a monolayer of CdTe microcrystals, where a single microcrystalline particle is typically one micron in size. Focus is made on the dominant band of “super-hot” emission appearing in the spectral region located in energy above the fundamental absorption edge of a CdTe bulk crystal. A theoretical model has been developed that assumes the existence of a space-charge layer inside a microcrystal, which leads to the formation of a triangular potential well for an electron near the surface. The anomalous emission band arises as a result of the optical transitions of electrons from near-surface levels of spatial quantization to valence band states.展开更多
The quantum features of the temporal photon statistics of an exciton-cavity coupled system in a quantum-well semiconductor microcavity are investigated analytically. Under the secular approximation, if the nonlinear i...The quantum features of the temporal photon statistics of an exciton-cavity coupled system in a quantum-well semiconductor microcavity are investigated analytically. Under the secular approximation, if the nonlinear interactions, i.e. the exciton-exciton coupling and the phase-space filling, are much weaker than the exciton-photon interaction, the evolution of the Fano factor shows that the distribution of the photon numbers exhibits the feature of collapses-revivals （CRs）, and the relevant revival time may be adjusted by several factors such as the total particle number, the detuning, and the nonlinear coupling strengths, etc. Especially, the ideal maximum antibunching with the minimum value 0 of the Fano factor occurs periodically for such a situation, with the dissipation of exciton-polariton being ignored.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 16Z103060007) (PA)。
文摘We investigate the transfer of phosphorescent energy between co-assembled metallophosphors in crystalline nanostructures [Angew. Chem. Int. Ed. 57 7820(2018) and J. Am. Chem. Soc. 140 4269(2018)]. Neither Dexter's nor Forster's mechanism of resonance energy transfer(RET) could account fully for the observed rates, which exceed 85% with significant temperature dependence. But there exists an alternative pathway on RET mediated by intermediate states of resonantly confined exciton–polaritons. Such a mechanism was used to analyze artificial photosynthesis in organic fluorescents [Phys.Rev. Lett. 122 257402(2019)]. For metallophosphors, the confined modes act as extended states lying between the molecular S_(1) and T_(1) states, offering a bridge for the long-lived T_(1) excitons to migrate from donors to acceptors. Population dynamics with parameters taken entirely based on experiments fits the observed lifetimes of phosphorescence across a broad range of doping and temperature.
基金Q.Xiong gratefully acknowledges funding support from the National Natural Science Foundation of China(12020101003)the State Key Laboratory of Low-Dimensional Quantum Physics at Tsinghua University.S.Ghosh gratefully acknowledges the support from the Excellent Young Scientists Fund Program(Overseas)of the National Natural Science Foundation of China.R.Su and T.Liew gratefully acknowledge the funding support from Nanyang Technological University via a start-up grant and the Singapore Ministry of Education via the AcRF Tier 3 Programme“Geometrical Quantum Materials”(MOE2018-T3-1-002).
文摘The quest for realizing novel fundamental physical effects and practical applications in ambient conditions has led to tremendous interest in microcavity exciton polaritons working in the strong coupling regime at room temperature.In the past few decades,a wide range of novel semiconductor systems supporting robust exciton polaritons have emerged,which has led to the realization of various fascinating phenomena and practical applications.This paper aims to review recent theoretical and experimental developments of exciton polaritons operating at room temperature,and includes a comprehensive theoretical background,descriptions of intriguing phenomena observed in various physical systems,as well as accounts of optoelectronic applications.Specifically,an in-depth review of physical systems achieving room temperature exciton polaritons will be presented,including the early development of ZnO and GaN microcavities and other emerging systems such as organics,halide perovskite semiconductors,carbon nanotubes,and transition metal dichalcogenides.Finally,a perspective of outlooking future developments will be elaborated.
基金Project supported partly by PhD Progress Foundation of Higher Education Institutions of China （Grant No 20040126003） and the Natural Science Foundation of Inner Mongol of China （Grant No 200408020101）.
文摘In this paper the bulk exciton polaritons in ternary mixed crystals （TMCs） are investigated in the Born-Huang approximation. The numerical results of the polariton frequencies as functions of the wave-vector and the compositions for ternary mixed crystals AlxGa1-xAs, CdxZn1-xSe, and AlxGa1-xN are obtained and discussed. The new dispersion characteristics for exciton-polaritons in TMC systems are found in comparison with binary crystals. The splitting of the two branches of exciton-polariton frequencies varies nonlinearly with the composition of TMCs and has a minimum in the long-wavelength range.
文摘The low-temperature (T = 2 K) exciton-polariton luminescence (EPL) spectra in the vicinity of the exciton-resonance frequency An=1 for CdS-type crystals have been theoretically and experimentally investigated with allowance for the mechanical exciton decay . The results of the numerical calculations of the partial and interference contributions of the bulk and radiative surface spectral modes to the EPL in the geometry of additional s- and p-polarized waves emitted into vacuum are analyzed. It is shown that the contributions of purely longitudinal excitons and their interference with polaritons of the upper dispersion branch near the longitudinal frequency ωL to the EPL are small (∼10% - 30%);nevertheless, they must be taken into account to obtain quantitative agreement with experimental data. Specifically these contributions are responsible for the formation of an additional line (along with the fundamental AT line) in the case of oblique incidence of radiation.
基金supported by the National Natural Sci-ence Foundation of China(No.21972083,No.22102129)the Fundamental Research Funds for the Central Universities(GK202102008)+1 种基金the Support Program for top-notch young talents in Shaanxi Province(1511000066)the China Postdoctoral Science Foundation(2021M692615,2022T150528)。
文摘The scope of the study is the spectra of low-temperature (T = 2K) photoluminescence of a p-CdTe/n-CdS film heterostructure comprising a monolayer of CdTe microcrystals, where a single microcrystalline particle is typically one micron in size. Focus is made on the dominant band of “super-hot” emission appearing in the spectral region located in energy above the fundamental absorption edge of a CdTe bulk crystal. A theoretical model has been developed that assumes the existence of a space-charge layer inside a microcrystal, which leads to the formation of a triangular potential well for an electron near the surface. The anomalous emission band arises as a result of the optical transitions of electrons from near-surface levels of spatial quantization to valence band states.
文摘The quantum features of the temporal photon statistics of an exciton-cavity coupled system in a quantum-well semiconductor microcavity are investigated analytically. Under the secular approximation, if the nonlinear interactions, i.e. the exciton-exciton coupling and the phase-space filling, are much weaker than the exciton-photon interaction, the evolution of the Fano factor shows that the distribution of the photon numbers exhibits the feature of collapses-revivals （CRs）, and the relevant revival time may be adjusted by several factors such as the total particle number, the detuning, and the nonlinear coupling strengths, etc. Especially, the ideal maximum antibunching with the minimum value 0 of the Fano factor occurs periodically for such a situation, with the dissipation of exciton-polariton being ignored.
