Graphene,as a saturable absorber(SA),has attracted much attention for its application in ultrashort pulse fiber lasers due to its ultrafast interband carrier relaxation and ultra-broadband wavelength operation.Neverth...Graphene,as a saturable absorber(SA),has attracted much attention for its application in ultrashort pulse fiber lasers due to its ultrafast interband carrier relaxation and ultra-broadband wavelength operation.Nevertheless,during the stacking process of monolayer graphene layer,the induced nonuniform contact at the interface of graphene layers deteriorate the device performance.Herein,we report the fabrication of graphene saturable absorber mirrors(SAMs)via a one-step transfer process and the realization of the much enlarged modulation depth and the much reduced nonsaturable loss with tri-layer graphene(TLG)than single-layer graphene(SLG)due to the improved uniform contact at the interface.Moreover,the operation of 1550 nm mode-locked Er-doped fiber laser with the TLG SAM exhibits excellent output characteristics of the maximum output power of 9.9 mW,a slope efficiency of 2.4%and a pulse width of 714 fs.Our findings are expected to pave the way toward high-performance ultrashort pulse fiber lasers based on graphene SAs.展开更多
Supercapacitors(SCs)are emerging as efficient energy storage devices but still suffering from limited energy density compared with batteries.Electrolytes have been regarded as the key to determine the energy storage p...Supercapacitors(SCs)are emerging as efficient energy storage devices but still suffering from limited energy density compared with batteries.Electrolytes have been regarded as the key to determine the energy storage performance of SCs.However,none of the conventional electrolytes can fully meet the increasing requirements of SCs in terms of high ion conductivity,excellent stability,wide voltage window and operating temperature range,as well as environmentally friend concerns.To this end,hybrid electrolytes have sprung up in recent years,which are believed to be the candidate to solve these shortcomings.Herein,the state-of-the-art types of hybrid electrolytes for SCs,including the combination of aqueous and organic,aqueous and gel polymer,ionic liquids(ILs)and organic,and ILs and gel polymer hybrid electrolytes,are reviewed.The effects of different hybrid systems on the performance of SCs and the underlying mechanisms are among the focal points of the review,and prospects and possible directions are discussed as well to provide further insight into the future development of this field.展开更多
Quantum cascade(QC)superluminescent light emitters(SLEs)have emerged as desirable broadband mid-infrared(MIR)light sources for growing number of applications in areas like medical imaging,gas sensing and national defe...Quantum cascade(QC)superluminescent light emitters(SLEs)have emerged as desirable broadband mid-infrared(MIR)light sources for growing number of applications in areas like medical imaging,gas sensing and national defense.However,it is challenging to obtain a practical high-power device due to the very low efficiency of spontaneous emission in the intersubband transitions in QC structures.Herein a design of^5μm SLEs is demonstrated with a two-phonon resonancebased QC active structure coupled with a compact combinatorial waveguide structure which comprises a short straight part adjacent to a tilted stripe and to a J-shaped waveguide.The as-fabricated SLEs achieve a high output power of 1.8 mW,exhibiting the potential to be integrated into array devices without taking up too much chip space.These results may facilitate the realization of SLE arrays to attain larger output power and pave the pathway towards the practical applications of broadband MIR light sources.展开更多
Excited-states play a crucial role in the optical absorption and luminescence of solids and hence their accurate information is highly desired. Herein, we attempt to seize the excited-states information of Mn^(4+)ions...Excited-states play a crucial role in the optical absorption and luminescence of solids and hence their accurate information is highly desired. Herein, we attempt to seize the excited-states information of Mn^(4+)ions in K_(2)SiF_(6) microcrystals via measuring and calculating their variable-temperature photoluminescence excitation(PLE) spectra. At cryogenic temperatures, an unpredicted splitting of the high-excited-state is observed. Moreover, the two-split high-excited-state levels are further revealed to primarily couple with the two hyperfine split modes of quasi-localized ν2 vibration in the distorted Mn-F_(6) octahedral configuration,whereas the coupling strengths are found to be substantially different from each other. The slightly split vibrational mode is firmly supported by the low-temperature Raman spectra. Jahn-Teller lattice distortion is believed to be responsible for the observed splitting of the electronic high-excited-state and the quasi-localized vibrational mode.展开更多
Supercapacitors(SCs)are rated as the foremost efficient devices bridging the production and consumption of renewable energy.To address the ever-increasing energy requirements,it is indispensable to further develop hig...Supercapacitors(SCs)are rated as the foremost efficient devices bridging the production and consumption of renewable energy.To address the ever-increasing energy requirements,it is indispensable to further develop high-performance SCs with merits of high energy-density,acceptable price and long-term stability.This review highlights the recent advances on halogen-based functionalized chemistry engineering in the state-of-the-art electrode system for high-performance SCs,primarily referring to the doping and decoration strategies of F,Cl,Br and I elements.Due to the discrepancy of electronegativity and atomic radius,the functionalization of each halogen element endows the substrate materials with different physicochemical properties,including energy bandgap structure,porosity distribution and surface affinity.The principle of halogen embedment into host materials by precisely controlling ionic adsorption and electronic structure is presented.And,the vital perspectives on the future challenges of halogen functionalization are also discussed.This work aims to deepen the understanding of halogen-based functionalized strategies to motivate further research for the development of high-performance SCs,and it also provides a prospect for exploring new material modification methods for electrochemical energy storage.展开更多
Supercapacitors(SCs) with high power density and long cycling span life are demanding energy storage devices that will be an attractive power solution to modern electronic and electrical applications. Numerous theoret...Supercapacitors(SCs) with high power density and long cycling span life are demanding energy storage devices that will be an attractive power solution to modern electronic and electrical applications. Numerous theoretical and experimental works have been devoted to exploring various possibilities to increase the functionality and the specific capacitance of electrodes for SCs. Non-carbon two-dimensional(2D)materials have been considered as encouraging electrode candidates for their chemical and physical advantages such as tunable surface chemistry, high electronic conductivity, large mechanical strength, more active sites, and dual non-faradaic and faradaic electrochemical performances. Besides, these 2D materials also play particular roles in constructing highway channels for fast ion diffusion. This concise review summarizes cutting-edge progress of some representative 2D non-carbon materials for the aqueous electrolyte-based SCs, including transition metal oxides(TMOs), transition metal hydroxides(TMHs), transition metal chalcogenides(TMCs), MXenes, metal-organic frameworks(MOFs) and some emerging materials. Different synthetic methods, effective structural designs and corresponding electrochemical performances are reviewed in detail. And we finally present a detailed discussion of the current intractable challenges and technical bottlenecks, and highlight future directions and opportunities for the development of next-generation high-performance energy storage devices.展开更多
过渡金属氧化态调控工程是一种很有前景的改善电极材料的氧化还原活性、增加活性位点的策略.本文提出了一种简单的三乙醇胺辅助自模板法,制备了一种由交错钴硫化物纳米片(Co_(x)S_(y)-T NSs)组装而成的独特的三维蜂窝状网络结构.有趣的...过渡金属氧化态调控工程是一种很有前景的改善电极材料的氧化还原活性、增加活性位点的策略.本文提出了一种简单的三乙醇胺辅助自模板法,制备了一种由交错钴硫化物纳米片(Co_(x)S_(y)-T NSs)组装而成的独特的三维蜂窝状网络结构.有趣的是,我们首次发现在该体系中,三乙醇胺可以有效地增加目标产物中的高价态Co^(3+)的比例.Co_(x)S_(y)-T NSs电极具有高含量的Co^(3+)和三维网络结构,使得其在5 A g^(-1)的电流密度下表现出351 mA h g^(-1)(2635 F g^(-1))的最大比容量和优异的循环稳定性.此外,由Co_(x)S_(y)-T NSs和活性炭(AC)电极组装的固态不对称超级电容器在0.81 kW kg^(-1)功率密度下展现出81.62 W h kg^(-1)的高能量密度和卓越的长周期循环稳定性,7000次循环后仍有96.2%的容量保持率.该结果证明同时调控高价态的金属物种并构筑三维网络结构是一种简单而有效的制备用于能源存储与转换的高活性电极材料的策略.展开更多
In this paper, influence of temperature and reverse bias on photocurrent spectrum and spectral response of a monolithic GalnP/GaAs double-junction solar cell was investigated in detail. Two sharp spectral response off...In this paper, influence of temperature and reverse bias on photocurrent spectrum and spectral response of a monolithic GalnP/GaAs double-junction solar cell was investigated in detail. Two sharp spectral response offsets, corresponding to the bandedge photo absorption of the bottom GaAs and the top GalnP subcells, respectively, show the starting response points of individual subcells. More interestingly, the cell photocurrent was found to enhance significantly with increasing the temperature. In addition, the cell photocurrent also increases obviously as the reverse bias voltage increases. The integrated photocurrent intensity of the top GalnP subcell was particularly addressed. A theoretical model was proposed to simulate the reverse bias dependence of the integrated photocurrent of the GalnP subceU at different temperatures.展开更多
基金supported by the Key Research and Development Plan of Ministry of Science and Technology(2016YFB0402303)National Natural Science Foundation of China(NSFC)(61875222,61605106)China Postdoctoral Science Foundation(2017M621858)
文摘Graphene,as a saturable absorber(SA),has attracted much attention for its application in ultrashort pulse fiber lasers due to its ultrafast interband carrier relaxation and ultra-broadband wavelength operation.Nevertheless,during the stacking process of monolayer graphene layer,the induced nonuniform contact at the interface of graphene layers deteriorate the device performance.Herein,we report the fabrication of graphene saturable absorber mirrors(SAMs)via a one-step transfer process and the realization of the much enlarged modulation depth and the much reduced nonsaturable loss with tri-layer graphene(TLG)than single-layer graphene(SLG)due to the improved uniform contact at the interface.Moreover,the operation of 1550 nm mode-locked Er-doped fiber laser with the TLG SAM exhibits excellent output characteristics of the maximum output power of 9.9 mW,a slope efficiency of 2.4%and a pulse width of 714 fs.Our findings are expected to pave the way toward high-performance ultrashort pulse fiber lasers based on graphene SAs.
基金financial support from the National Natural Science Foundation of China(21671173)Zhejiang Provincial Ten Thousand Talent Program(2017R52043)。
文摘Supercapacitors(SCs)are emerging as efficient energy storage devices but still suffering from limited energy density compared with batteries.Electrolytes have been regarded as the key to determine the energy storage performance of SCs.However,none of the conventional electrolytes can fully meet the increasing requirements of SCs in terms of high ion conductivity,excellent stability,wide voltage window and operating temperature range,as well as environmentally friend concerns.To this end,hybrid electrolytes have sprung up in recent years,which are believed to be the candidate to solve these shortcomings.Herein,the state-of-the-art types of hybrid electrolytes for SCs,including the combination of aqueous and organic,aqueous and gel polymer,ionic liquids(ILs)and organic,and ILs and gel polymer hybrid electrolytes,are reviewed.The effects of different hybrid systems on the performance of SCs and the underlying mechanisms are among the focal points of the review,and prospects and possible directions are discussed as well to provide further insight into the future development of this field.
基金supported by the Key Research and Development Plan of Ministry of Science and Technology(No.2016YFB0402303)the National Natural Science Foundation of China(No.61575222)+1 种基金the open project of the State Key Laboratory of Luminescence and ApplicationsChina Postdoctoral Science Foundation(No.2017M621858)
文摘Quantum cascade(QC)superluminescent light emitters(SLEs)have emerged as desirable broadband mid-infrared(MIR)light sources for growing number of applications in areas like medical imaging,gas sensing and national defense.However,it is challenging to obtain a practical high-power device due to the very low efficiency of spontaneous emission in the intersubband transitions in QC structures.Herein a design of^5μm SLEs is demonstrated with a two-phonon resonancebased QC active structure coupled with a compact combinatorial waveguide structure which comprises a short straight part adjacent to a tilted stripe and to a J-shaped waveguide.The as-fabricated SLEs achieve a high output power of 1.8 mW,exhibiting the potential to be integrated into array devices without taking up too much chip space.These results may facilitate the realization of SLE arrays to attain larger output power and pave the pathway towards the practical applications of broadband MIR light sources.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12074324, and 11374247)the Science, Technology, and Innovation Commission of Shenzhen Municipality (Grant Nos. JCJY20180508163404043, and JCYJ20170818141709893)。
文摘Excited-states play a crucial role in the optical absorption and luminescence of solids and hence their accurate information is highly desired. Herein, we attempt to seize the excited-states information of Mn^(4+)ions in K_(2)SiF_(6) microcrystals via measuring and calculating their variable-temperature photoluminescence excitation(PLE) spectra. At cryogenic temperatures, an unpredicted splitting of the high-excited-state is observed. Moreover, the two-split high-excited-state levels are further revealed to primarily couple with the two hyperfine split modes of quasi-localized ν2 vibration in the distorted Mn-F_(6) octahedral configuration,whereas the coupling strengths are found to be substantially different from each other. The slightly split vibrational mode is firmly supported by the low-temperature Raman spectra. Jahn-Teller lattice distortion is believed to be responsible for the observed splitting of the electronic high-excited-state and the quasi-localized vibrational mode.
基金financially supported by the National Natural Science Foundation of China(12074324 and 11374247)the Science,Technology,and Innovation Commission of Shenzhen Municipality(JCJY20180508163404043 and JCYJ20170818141709893)。
基金financially supported by the Major Program of Zhejiang Provincial Natural Science Foundation of China(No.LD22B030002)Zhejiang Provincial Ten Thousand Talent Programthe Independent Designing Scientific Research Project of Zhejiang Normal University(No.2020ZS03)。
文摘Supercapacitors(SCs)are rated as the foremost efficient devices bridging the production and consumption of renewable energy.To address the ever-increasing energy requirements,it is indispensable to further develop high-performance SCs with merits of high energy-density,acceptable price and long-term stability.This review highlights the recent advances on halogen-based functionalized chemistry engineering in the state-of-the-art electrode system for high-performance SCs,primarily referring to the doping and decoration strategies of F,Cl,Br and I elements.Due to the discrepancy of electronegativity and atomic radius,the functionalization of each halogen element endows the substrate materials with different physicochemical properties,including energy bandgap structure,porosity distribution and surface affinity.The principle of halogen embedment into host materials by precisely controlling ionic adsorption and electronic structure is presented.And,the vital perspectives on the future challenges of halogen functionalization are also discussed.This work aims to deepen the understanding of halogen-based functionalized strategies to motivate further research for the development of high-performance SCs,and it also provides a prospect for exploring new material modification methods for electrochemical energy storage.
基金financial support from National Natural Science Foundation of China (No. 21671173)the Independent Designing Scientific Research Project of Zhejiang Normal University (No. 2020ZS03)Zhejiang Provincial Ten Thousand Talent Program (No. 2017R52043)。
文摘Supercapacitors(SCs) with high power density and long cycling span life are demanding energy storage devices that will be an attractive power solution to modern electronic and electrical applications. Numerous theoretical and experimental works have been devoted to exploring various possibilities to increase the functionality and the specific capacitance of electrodes for SCs. Non-carbon two-dimensional(2D)materials have been considered as encouraging electrode candidates for their chemical and physical advantages such as tunable surface chemistry, high electronic conductivity, large mechanical strength, more active sites, and dual non-faradaic and faradaic electrochemical performances. Besides, these 2D materials also play particular roles in constructing highway channels for fast ion diffusion. This concise review summarizes cutting-edge progress of some representative 2D non-carbon materials for the aqueous electrolyte-based SCs, including transition metal oxides(TMOs), transition metal hydroxides(TMHs), transition metal chalcogenides(TMCs), MXenes, metal-organic frameworks(MOFs) and some emerging materials. Different synthetic methods, effective structural designs and corresponding electrochemical performances are reviewed in detail. And we finally present a detailed discussion of the current intractable challenges and technical bottlenecks, and highlight future directions and opportunities for the development of next-generation high-performance energy storage devices.
基金the National Natural Science Foundation of China(21671173)Zhejiang Provincial Ten Thousand Talent Program(2017R52043)。
文摘过渡金属氧化态调控工程是一种很有前景的改善电极材料的氧化还原活性、增加活性位点的策略.本文提出了一种简单的三乙醇胺辅助自模板法,制备了一种由交错钴硫化物纳米片(Co_(x)S_(y)-T NSs)组装而成的独特的三维蜂窝状网络结构.有趣的是,我们首次发现在该体系中,三乙醇胺可以有效地增加目标产物中的高价态Co^(3+)的比例.Co_(x)S_(y)-T NSs电极具有高含量的Co^(3+)和三维网络结构,使得其在5 A g^(-1)的电流密度下表现出351 mA h g^(-1)(2635 F g^(-1))的最大比容量和优异的循环稳定性.此外,由Co_(x)S_(y)-T NSs和活性炭(AC)电极组装的固态不对称超级电容器在0.81 kW kg^(-1)功率密度下展现出81.62 W h kg^(-1)的高能量密度和卓越的长周期循环稳定性,7000次循环后仍有96.2%的容量保持率.该结果证明同时调控高价态的金属物种并构筑三维网络结构是一种简单而有效的制备用于能源存储与转换的高活性电极材料的策略.
基金This work was financially supported by the National Natural Science Foundation of China (Grant No. 11374247)
文摘In this paper, influence of temperature and reverse bias on photocurrent spectrum and spectral response of a monolithic GalnP/GaAs double-junction solar cell was investigated in detail. Two sharp spectral response offsets, corresponding to the bandedge photo absorption of the bottom GaAs and the top GalnP subcells, respectively, show the starting response points of individual subcells. More interestingly, the cell photocurrent was found to enhance significantly with increasing the temperature. In addition, the cell photocurrent also increases obviously as the reverse bias voltage increases. The integrated photocurrent intensity of the top GalnP subcell was particularly addressed. A theoretical model was proposed to simulate the reverse bias dependence of the integrated photocurrent of the GalnP subceU at different temperatures.