The optical response of metal nanoparticles can be modified through near-field or far-field interaction,yet the lattice plasmon modes(LPMs)considered can only be excited from the latter.Here instead,we present a theor...The optical response of metal nanoparticles can be modified through near-field or far-field interaction,yet the lattice plasmon modes(LPMs)considered can only be excited from the latter.Here instead,we present a theoretical evaluation for LPM excitation via the near-field coupling process.The sample is an arrayed structure with specific units composed of upper metal disks,a lower metal hole and a sandwiched dielectric post.The excitation process and underlying mechanism of the LPM and the influence of the structure parameters on the optical properties have been investigated in detail by using a finite-difference time-domain(FDTD)numerical method.Our investigation presented here should advance the understanding of near-field interaction of plasmon modes for LPM excitation,and LPMs could find some potential applications,such as in near-field optical microscopes,biosensors,optical filters and plasmonic lasers.展开更多
Nitrogen-doped graphene is a promising candidate for the replacement of noble metal-based electrocatalysts for oxygen reduction reactions （ORRs）. The addition of pores and holes into nitrogen-doped graphene enhances...Nitrogen-doped graphene is a promising candidate for the replacement of noble metal-based electrocatalysts for oxygen reduction reactions （ORRs）. The addition of pores and holes into nitrogen-doped graphene enhances the ORR activity by introducing abundant exposed edges, accelerating mass transfer, and impeding aggregation of the graphene sheets. Herein, we present a straightforward but effective strategy for generating porous holey nitrogen-doped graphene （PHNG） via the pyrolysis of urea and magnesium acetate tetrahydrate. Due to the combined effects of the in situ generated gases and MgO nanoparticles, the synthesized PHNGs featured not only numerous out-of-plane pores among the crumpled graphene sheets, but also interpenetrated nanoscale （5-15 nm） holes in the assembled graphene. Moreover, the nitrogen doping configurations of PHNG were optimized by post-thermal treatments at different temperatures. It was found that the overall content of pyridinic and quaternary nitrogen positively correlates with the ORR activity; in particular, pyridinic nitrogen generates the most desirable characteristics for the ORR. This work reveals new routes for the synthesis of PHNG-based materials and elucidates the contributions of various nitrogen species to ORRs.展开更多
To achieve high quality lighting and visible light communication(VLC)simultaneously,Ga N based white light emitting diodes(WLEDs)oriented for lighting in VLC has attracted great interest.However,the overall bandwidth ...To achieve high quality lighting and visible light communication(VLC)simultaneously,Ga N based white light emitting diodes(WLEDs)oriented for lighting in VLC has attracted great interest.However,the overall bandwidth of conventional phosphor converted WLEDs is limited by the long lifetime of phosphor,the slow Stokes transfer process,the resistance-capacitance(RC)time delay,and the quantum-confined Stark effect(QCSE).Here by adopting a self-assembled In Ga N quantum dots(QDs)structure,we have fabricated phosphor-free single chip WLEDs with tunable correlated color temperature(CCT,from 1600 K to 6000 K),a broadband spectrum,a moderate color rendering index(CRI)of 75,and a significantly improved modulation bandwidth(maximum of150 MHz)at a low current density of 72 A∕cm^2.The broadband spectrum and high modulation bandwidth are ascribed to the capture of carriers by different localized states of In Ga N QDs with alleviative QCSE as compared to the traditional In Ga N/Ga N quantum well(QW)structures.We believe the approach reported in this work will find its potential application in Ga N WLEDs and advance the development of semiconductor lighting-communication integration.展开更多
Commercial white LEDs (WLEDs) are generally limited in modulation bandwidth due to a slow Stokes process,long lifetime of phosphors,and the quantum-confined Stark effect. Here we report what we believe is a novel plas...Commercial white LEDs (WLEDs) are generally limited in modulation bandwidth due to a slow Stokes process,long lifetime of phosphors,and the quantum-confined Stark effect. Here we report what we believe is a novel plasmonic WLED by infiltrating a nanohole LED (H-LED) with quantum dots (QDs) and Ag nanoparticles(NPs) together (M-LED). This decreased distance between quantum wells and QDs would open an extra non-radiative energy transfer channel and thus enhance Stokes transfer efficiency. The presence of Ag NPs enhances the spontaneous emission rate significantly. Compared to an H-LED filled with QDs (QD-LED),the optimized M-LED demonstrates a maximum color rendering index of 91.2,a 43% increase in optical power at 60 m A,and a lowered correlated color temperature. Simultaneously,the M-LED exhibits a data rate of 2.21 Gb/s at low current density of 96 A∕cm2(60 m A),which is 77% higher than that of a QD-LED. This is mainly due to the higher optical power and modulation bandwidth of the M-LED under the influence of plasmon,resulting in a higher data rate and higher signal-to-noise ratio under the forward error correction.We believe the approach reported in this work should contribute to a WLED light source with increased modulation bandwidth for a higher speed visible light communication application.展开更多
基金Key Laboratory of Energy Conversion and Storage Technologies(Southern University of Science and Technology),Ministry of Education,Shenzhen,China,the National Key Research and Development Program of China(Grant No.2018YFB0406702)Professorship Startup Funding(Grant No.217056)+1 种基金Innovation-Driven Project of Central South University(Grant No.2018CX001)Project of State Key Laboratory of High Performance Complex Manufacturing,Central South University(Grant No.ZZYJKT2018-01).
文摘The optical response of metal nanoparticles can be modified through near-field or far-field interaction,yet the lattice plasmon modes(LPMs)considered can only be excited from the latter.Here instead,we present a theoretical evaluation for LPM excitation via the near-field coupling process.The sample is an arrayed structure with specific units composed of upper metal disks,a lower metal hole and a sandwiched dielectric post.The excitation process and underlying mechanism of the LPM and the influence of the structure parameters on the optical properties have been investigated in detail by using a finite-difference time-domain(FDTD)numerical method.Our investigation presented here should advance the understanding of near-field interaction of plasmon modes for LPM excitation,and LPMs could find some potential applications,such as in near-field optical microscopes,biosensors,optical filters and plasmonic lasers.
基金supported by the National Natural Science Foundation of China(62090035,U19A2090,61905071)the Key Program of the Hunan Provincial Science and Technology Department(2019XK2001,2020XK2001)+2 种基金the International Science and Technology Innovation Cooperation Base of Hunan Province(2018WK4004)the China Postdoctoral Science Foundation(2022TQ0100)the National Key Research and 288 Development Program of China(2022YFB3604701).
基金Acknowledgements We gratefully acknowledge the financial support from the National Natural Science Foundation of China （Nos. 21503253, 21403276 and 91545109）, Natural Science Foundation of Shan-Xi province of China （No. 2015011010）, and Youth Innovation Promotion Association CAS （No. 2015141）.
文摘Nitrogen-doped graphene is a promising candidate for the replacement of noble metal-based electrocatalysts for oxygen reduction reactions （ORRs）. The addition of pores and holes into nitrogen-doped graphene enhances the ORR activity by introducing abundant exposed edges, accelerating mass transfer, and impeding aggregation of the graphene sheets. Herein, we present a straightforward but effective strategy for generating porous holey nitrogen-doped graphene （PHNG） via the pyrolysis of urea and magnesium acetate tetrahydrate. Due to the combined effects of the in situ generated gases and MgO nanoparticles, the synthesized PHNGs featured not only numerous out-of-plane pores among the crumpled graphene sheets, but also interpenetrated nanoscale （5-15 nm） holes in the assembled graphene. Moreover, the nitrogen doping configurations of PHNG were optimized by post-thermal treatments at different temperatures. It was found that the overall content of pyridinic and quaternary nitrogen positively correlates with the ORR activity; in particular, pyridinic nitrogen generates the most desirable characteristics for the ORR. This work reveals new routes for the synthesis of PHNG-based materials and elucidates the contributions of various nitrogen species to ORRs.
基金National Key Research and Development Program of China(2018YFB0406702)Professorship Startup Funding(217056)+2 种基金Innovation-Driven Project of Central South University,China(2018CX001)Project of State Key Laboratory of High-Performance Complex Manufacturing,Central South University,China(ZZYJKT2018-01)Fundamental Research Funds for the Central Universities of Central South University(2018zzts147)。
文摘To achieve high quality lighting and visible light communication(VLC)simultaneously,Ga N based white light emitting diodes(WLEDs)oriented for lighting in VLC has attracted great interest.However,the overall bandwidth of conventional phosphor converted WLEDs is limited by the long lifetime of phosphor,the slow Stokes transfer process,the resistance-capacitance(RC)time delay,and the quantum-confined Stark effect(QCSE).Here by adopting a self-assembled In Ga N quantum dots(QDs)structure,we have fabricated phosphor-free single chip WLEDs with tunable correlated color temperature(CCT,from 1600 K to 6000 K),a broadband spectrum,a moderate color rendering index(CRI)of 75,and a significantly improved modulation bandwidth(maximum of150 MHz)at a low current density of 72 A∕cm^2.The broadband spectrum and high modulation bandwidth are ascribed to the capture of carriers by different localized states of In Ga N QDs with alleviative QCSE as compared to the traditional In Ga N/Ga N quantum well(QW)structures.We believe the approach reported in this work will find its potential application in Ga N WLEDs and advance the development of semiconductor lighting-communication integration.
基金National Key Research and Development Program of China (2018YFB0406702)National Natural Science Foundation of China (61925104)+1 种基金Key Laboratory of Energy Conversion and Storage Technologies (Southern University of Science and Technology),Ministry of Education,ShenzhenFundamental Research Funds for the Central Universities of Central South University (2018zzts147)。
文摘Commercial white LEDs (WLEDs) are generally limited in modulation bandwidth due to a slow Stokes process,long lifetime of phosphors,and the quantum-confined Stark effect. Here we report what we believe is a novel plasmonic WLED by infiltrating a nanohole LED (H-LED) with quantum dots (QDs) and Ag nanoparticles(NPs) together (M-LED). This decreased distance between quantum wells and QDs would open an extra non-radiative energy transfer channel and thus enhance Stokes transfer efficiency. The presence of Ag NPs enhances the spontaneous emission rate significantly. Compared to an H-LED filled with QDs (QD-LED),the optimized M-LED demonstrates a maximum color rendering index of 91.2,a 43% increase in optical power at 60 m A,and a lowered correlated color temperature. Simultaneously,the M-LED exhibits a data rate of 2.21 Gb/s at low current density of 96 A∕cm2(60 m A),which is 77% higher than that of a QD-LED. This is mainly due to the higher optical power and modulation bandwidth of the M-LED under the influence of plasmon,resulting in a higher data rate and higher signal-to-noise ratio under the forward error correction.We believe the approach reported in this work should contribute to a WLED light source with increased modulation bandwidth for a higher speed visible light communication application.
