The electron-hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots （Cdots） is still not clear. In this study,...The electron-hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots （Cdots） is still not clear. In this study, we have developed a simple and efficient one-step strategy to synthesize luminescent Cdots using the pyrolysis of oleylamine. The sp^2 clusters of a few aromatic rings are responsible for the observed blue photoluminescence. The size of these clusters can be tuned by controlling the reaction time, and the energy gap between the π-π＊ states of the sp^2 domains decreases as the sp^2 cluster size increases. More importantly, the strong electron-hole exchange interaction results in the splitting of the exciton states of the sp^2 clusters into the singlet-bright and triplet-dark states with an energy difference ΔE, which decreases with increasing sp^2 cluster size owing to the reduction of the confinement energy and the suppression of the electron-hole exchange interaction.展开更多
The interlayer(IL) plays a vital role in hybrid white organic light-emitting diodes(WOLEDs); however,only a negligible amount of attention has been given to n-type ILs. Herein, the n-type IL, for the first time,has be...The interlayer(IL) plays a vital role in hybrid white organic light-emitting diodes(WOLEDs); however,only a negligible amount of attention has been given to n-type ILs. Herein, the n-type IL, for the first time,has been demonstrated to achieve a high efficiency, high color rendering index(CRI), and low voltage trade-off.The device exhibits a maximum total efficiency of 41.5 lm W^(-1), the highest among hybrid WOLEDs with n-type ILs. In addition, high CRIs(80–88) at practical luminances(C1000 cd m^(-2)) have been obtained, satisfying the demand for indoor lighting. Remarkably, a CRI of 88 is the highest among hybrid WOLEDs. Moreover, the device exhibits low voltages, with a turn-on voltage of only 2.5 V([1 cd m^(-2)), which is the lowest among hybrid WOLEDs. The intrinsic working mechanism of the device has also been explored; in particular, the role of n-type ILs in regulating the distribution of charges and excitons has been unveiled. The findings demonstrate that the introduction of n-type ILs is effective in developing high-performance hybrid WOLEDs.展开更多
Mass aggregations and migrations of millipedes despite numerous attempts to find causes for their occurrences are still an enigma. They have been reported from both southern and northern hemisphere countries, from hig...Mass aggregations and migrations of millipedes despite numerous attempts to find causes for their occurrences are still an enigma. They have been reported from both southern and northern hemisphere countries, from highlands and lowlands of both tropical and temperate regions and they can involve species belonging to the orders Julida and Spirobolida, Polydesmida and Glomerida. According to the main suggestions put forward in the past, mass occurrences in Diplopoda occur：（1） because of a lack of food and a population increase beyond sustainable levels;（2） for the purpose of reproduction and in order to locate suitable oviposition sites;（3） to find overwintering or aestivation sites;（4） because of habitat disruption and changes in the local environment;（5） as a consequence of weather conditions the year（or winter and spring） before. A recent outbreak（November 2014） of a mass migration of the polydesmid Chamberlinius hualienensis Wang 1956 on the Japanese Izu Island of Hachijojima 300 km to the south of Tokyo gave this author an opportunity to review the existing literature on millipede mass migrations and to carry out additional observations on the phenomenon in the field as well as the laboratory. Hitherto unreported heavy infestations with phoretic deutonymphs of the mite Histiostoma sp. as well as dense populations of internal rhabditid nematodes（Oscheius cf. necromena and an unidentified species of the genus Fictor）, suggest that infestations of this kind could be necromenic and either have been a contributing factor for the mass migration or been a consequence of so manyindividuals occurring together at close proximity. It is concluded that mass migrations and aggregations in millipedes do not have one common cause, but represent phenomena that often are seasonally recurring events and appear identical in their outcome, but which have evolved as responses to different causes in different millipede taxa and therefore need to be examined on a case-to-case basis.展开更多
During the regeneration of the tail in the arboreal New Zealand gecko （Hoplodactylus maculatus） a new set of tail scales, modified into pads bearing setae 5-20 μm long, is also regenerated. Stages of the formation ...During the regeneration of the tail in the arboreal New Zealand gecko （Hoplodactylus maculatus） a new set of tail scales, modified into pads bearing setae 5-20 μm long, is also regenerated. Stages of the formation of these specialized scales from epidermal pegs that invaginate the dermis of the regenerating tail are described on the basis of light and electron microscopic images. Within the pegs a differentiating clear layer interfaces with the spinulae and setae of the Oberh^utchen according to a process similar to that described for the digital pads. A layer of clear cytoplasm surrounds the growing tiny setae and eventually comities around them and their spatular ends, later leaving the new setae free- standing on the epidermal surface. The fresh adhesive pads help the gecko to maintain the prehensile function of its regenerated tail as together with the axial skeleton （made of a cylinder of elastic cartilage） the pads allow the regenerated tail to curl around twigs and small branches just like the original tail. The regeneration of caudal adhesive pads represents an ideal system to study the cellular processes that determine setal formation under normal or experimental manipulation as the progressive phases of the formation of the setae can be sequentially analyzed.展开更多
InGaN-based micro-light-emitting diodes(micro-LEDs)have been widely recognized as one of the critical technologies for high-resolution display applications.However,achieving high-efficiency,environmental-friendly,and ...InGaN-based micro-light-emitting diodes(micro-LEDs)have been widely recognized as one of the critical technologies for high-resolution display applications.However,achieving high-efficiency,environmental-friendly,and small-size self-emitting InGaN-based red micro-LEDs present significant challenges that impede the progress of monolithically integrated III-nitride full-color micro-LED displays.Current limitations stem from insufficient control over carrier dynamics in InGaN multiple quantum wells(MQWs),where conventional structures exhibit severe efficiency degradation due to insufficient hole injection and defect-induced nonradiative recombination.Herein,spatially-resolved in-situ hyperspectral imaging and numerical simulations demonstrate that optimized V-pit promote the effectiveness of three-dimensional current pathways and facilitate localized electric field redistribution.This improvement enhances hole injection while suppressing nonradiative recombination,this work contributes to the microstructure design in InGaN-based red LEDs.展开更多
The autism susceptibility candidate 2(AUTS2)gene1,2 at 7q11.2 was first identified and found disrupted because of a balanced translocation in a pair of monozygotic twins with autism spectrum disorder(ASD).Analysis of ...The autism susceptibility candidate 2(AUTS2)gene1,2 at 7q11.2 was first identified and found disrupted because of a balanced translocation in a pair of monozygotic twins with autism spectrum disorder(ASD).Analysis of 60 novel cases suggests that clinical phenotypes are more closely associated with intellectual disability rather than directly linked to ASD features.Human AUTS2 is a highly conserved gene that spans 1.2 Mb.Human AUTS2 protein has two major isoforms,full-length(1259 aa)and C-terminal(711 aa).Phenotypic analysis of patients indicated that they had borderline to severe intellectual disability/developmental delay,and 83%e100%had microcephaly.Mild dysmorphology was present.Specific traits of autism(like obsessive behavior)were seen frequently(83%).AUTS2 is also associated with alcohol consumption,heroin dependence,schizophrenia,and dyslexia,as analyzed using GWAS studies.展开更多
We propose and numerically test,to our knowledge,a novel concept for asymmetric vortex beam generation in a degenerate vertical external cavity surface emitting laser(DVECSEL).The method is based on a phase-locking ri...We propose and numerically test,to our knowledge,a novel concept for asymmetric vortex beam generation in a degenerate vertical external cavity surface emitting laser(DVECSEL).The method is based on a phase-locking ring array of lasers created inside a degenerate cavity with a binary amplitude mask containing circular holes.The diffraction engineering of the mask profile allows for controlling the complex coupling between the lasers.The asymmetry between different lasers is introduced by varying the hole diameters corresponding to different lasers.展开更多
Three-dimensional(3D)printing allows for the construction of complex structures.However,3D-printing vertical structures with a high aspect ratio remains a pending challenge,especially when a high lateral resolution is...Three-dimensional(3D)printing allows for the construction of complex structures.However,3D-printing vertical structures with a high aspect ratio remains a pending challenge,especially when a high lateral resolution is required.Here,to address this challenge,we propose and demonstrate micro-3D sculptured metastructures with deep trenches of 1:4(width:height)aspect ratio for sub-10µm resolution.Our construction relies on two-photon polymerization for a 3D-pattern with its trenches,followed by electroplating of a thick metal film and its dry etching to remove the seed layer.To test the proposed fabrication process,we built up three-dimensional RF metastructures showcasing the depth effect as the third dimension.Using the numerical solutions,we custom-tailored these metastructure resonators to fall within a specific resonance frequency range of 4-6 GHz while undertaking comparative analyses regarding overall footprint,quality factor,and resonance frequency shift as a function of their cross-sectional aspect ratio.The proposed process flow is shown to miniaturize metal footprint and tune the resonance frequency of these thick 3Dmetastructures while increasing their quality factor.These experimental findings indicate that this method of producing trenches via 3D-printing provides rich opportunities to implement high-aspect-ratio,complex structures.展开更多
The fabrication deviation of prisms and the error crosstalk are two major factors that produce serious systematic errors in dual-beam roll measurement based on a rhombic prism, and an error compensation method is put ...The fabrication deviation of prisms and the error crosstalk are two major factors that produce serious systematic errors in dual-beam roll measurement based on a rhombic prism, and an error compensation method is put forward in this letter to reduce these systematic errors. The rotation matrix, reflection matrix, and refraction matrix are used to calculate and obtain the mathematical relationship model of the roll angle as well as the fabrication deviation of prism and error crosstalk. The fabrication deviation can be obtained through comparison experiments and using the least square method. In this way, the systematic error of the roll measurement caused by fabrication deviation of prism and error crosstalk can be eliminated theoretically. The experimental results show that the maximum error of the roll angle measurement reduces evidently to 3.5″ from the previous 347.2″ after compensation.展开更多
Organic light-emitting diodes(OLEDs)are driven by injected charges from an anode and a cathode.The low and high work function metals are necessary for the effective injection of electrons and holes,respectively.Here,w...Organic light-emitting diodes(OLEDs)are driven by injected charges from an anode and a cathode.The low and high work function metals are necessary for the effective injection of electrons and holes,respectively.Here,we introduce a fully novel design concept using organic semiconductor heterojunctions(OSHJs)as the charge injectors for achieving highly efficient OLEDs,regardless of the work functions of the electrodes.In contrast to traditional injected charges from the electrodes,the injected charges originate from the OSHJs.The device performance was shown to be significantly improved in efficiency and stability compared to conventional OLEDs.Attractively,the OLEDs based on OSHJs as charge injectors still exhibited an impressive performance when the low work function Al was replaced by air-and chemistry-stable high work function metals,such as Au,Ag,and Cu,as the cathode contact,which has been suggested to be difficult in conventional OLEDs.This concept challenges the conventional design approach for the injection of charges and allows for the realization of practical applications of OLEDs with respect to high efficiency,selectable electrodes,and a long lifetime.展开更多
We report high-efficiency CdTe/CdS core/shell nanocrystals synthesized in water by epitaxially growing CdS shells on aqueous CdTe cores at room temperature,enabled by the controlled release of S species under low-inte...We report high-efficiency CdTe/CdS core/shell nanocrystals synthesized in water by epitaxially growing CdS shells on aqueous CdTe cores at room temperature,enabled by the controlled release of S species under low-intensity ultraviolet(UV)light illumination.The resulting photo-induced dissociation of S2O2-ions conveniently triggers the formation of critical two-dimensional CdS epitaxy on the CdTe surface at room temperature,as opposed to initiating the growth of individual CdS core-only nanocrystals.This controlled colloidal hetero-epitaxy leads to a substantial increase in the photoluminescence(PL)quantum yield(QY)of the shelled nanocrystals in water(reaching 64%).With a systematic set of studies,the maximum PL QY is found to be almost independent of the illuminating UV intensity,while the shell formation kinetics required for reaching the maximum QY linearly depends on the illuminating UV intensity.A stability study of the QD films in air at various temperatures shows highly improved thermal stability of the shelled QDs(up to 120℃in ambient air).These results indicate that the proposed aqueous CdTe/CdS core/shell nanocrystals hold great promise for applications requiring efficiency and stability.展开更多
The application of polymers to replace oleylamine(OLA)and oleic acid(OA)as ligands for perovskite nanocrystals is an effective strategy to improve their stability and durability especially for the solution-based proce...The application of polymers to replace oleylamine(OLA)and oleic acid(OA)as ligands for perovskite nanocrystals is an effective strategy to improve their stability and durability especially for the solution-based processing.Herein,we report a mechanosynthesis of lead bromide perovskite nanoparticles(NPs)stabilized by partially hydrolyzed poly(methyl methacrylate)(h-PMMA)and highmolecular-weight highly-branched poly(ethylenimine)(PEI-25K).The as-synthesized NP solutions exhibited green emission centered at 516 nm,possessing a narrow full-width at half-maximum of 17 nm and as high photoluminescence quantum yield(PL QY)as 85%,while showing excellent durability and resistance to polar solvents,e.g.,methanol.The colloids of polymer-stabilized NPs were directly processable toform stable and strongly-emitting thin films and solids,making them attractive as gain media.Furthermore,the roles of h-PMMA and PEI-25K in the grinding process were studied in depth.The h-PMMA can form micelles in the grinding solvent of dichloromethane to act as size-regulating templates for the growth of NPs.The PEI-25K with large amounts of amino groups induced significant enrichment of PbBr_(2)in the reaction mixture,which in turn caused the formation of CsPb_(2)Br_(5)-mPbBr_(2)and CsPbBr_(3)-Cs_(4)PbBr_(6)-nCsBr NPs.The presence of CsPbBr_(3)-Cs_(4)PbBr_(6)-nCsBr NPs was responsible for the high PL QY,as the Cs_(4)PbBr_(6)phase with a wide energy bandgap can passivate the surface defects of the CsPbBr_(3)phase.This work describes a direct and facile mechanosynthesis of polymer-coordinated perovskite NPs and promotes in-depth understanding of the formation and phase conversion for perovskite NPs in the grinding process.展开更多
Van der Waals heterojunctions are fast-emerging quantum structures fabricated by the controlled stacking of two-dimensional(2D)materials.Owing to the atomically thin thickness,their carrier properties are not only det...Van der Waals heterojunctions are fast-emerging quantum structures fabricated by the controlled stacking of two-dimensional(2D)materials.Owing to the atomically thin thickness,their carrier properties are not only determined by the host material itself,but also defined by the interlayer interactions,including dielectric environment,charge trapping centers,and stacking angles.The abundant constituents without the limitation of lattice constant matching enable fascinating electrical,optical,and magnetic properties in van der Waals heterojunctions toward next-generation devices in photonics,optoelectronics,and information sciences.This review focuses on the charge and energy transfer processes and their dynamics in transition metal dichalcogenides(TMDCs),a family of quantum materials with strong excitonic effects and unique valley properties,and other related 2D materials such as graphene and hexagonalboron nitride.In the first part,we summarize the ultrafast charge transfer processes in van der Waals heterojunctions,including its experimental evidence and theoretical understanding,the interlayer excitons at the TMDC interfaces,and the hot carrier injection at the graphene/TMDCs interface.In the second part,the energy transfer,including both Förster and Dexter types,are reviewed from both experimental and theoretical perspectives.Finally,we highlight the typical charge and energy transfer applications in photodetectors and summarize the challenges and opportunities for future development in this field.展开更多
A BP/CdS heterostructure-based artificial photonic synapse with an ultra-low power consumption is proposed,presenting great potential in high-performance neuromorphic vision systems.
With an increasing global population that is rapidly ageing,our society faces challenges that impact health,environment,and energy demand.With this ageing comes an accumulation of cellular changes that lead to the dev...With an increasing global population that is rapidly ageing,our society faces challenges that impact health,environment,and energy demand.With this ageing comes an accumulation of cellular changes that lead to the development of diseases and susceptibility to infections.This impacts not only the health system,but also the global economy.As the population increases,so does the demand for energy and the emission of pollutants,leading to a progressive degradation of our environment.This in turn impacts health through reduced access to arable land,clean water,and breathable air.New monitoring approaches to assist in environmental control and minimize the impact on health are urgently needed,leading to the development of new sensor technologies that are highly sensitive,rapid,and low-cost.Nanopore sensing is a new technology that helps to meet this purpose,with the potential to provide rapid point-of-care medical diagnosis,real-time on-site pollutant monitoring systems to manage environmental health,as well as integrated sensors to increase the efficiency and storage capacity of renewable energy sources.In this review we discuss how the powerful approach of nanopore based single-molecule,or particle,electrical promises to overcome existing and emerging societal challenges,providing new opportunities and tools for personalized medicine,localized environmental monitoring,and improved energy production and storage systems.展开更多
文摘The electron-hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots （Cdots） is still not clear. In this study, we have developed a simple and efficient one-step strategy to synthesize luminescent Cdots using the pyrolysis of oleylamine. The sp^2 clusters of a few aromatic rings are responsible for the observed blue photoluminescence. The size of these clusters can be tuned by controlling the reaction time, and the energy gap between the π-π＊ states of the sp^2 domains decreases as the sp^2 cluster size increases. More importantly, the strong electron-hole exchange interaction results in the splitting of the exciton states of the sp^2 clusters into the singlet-bright and triplet-dark states with an energy difference ΔE, which decreases with increasing sp^2 cluster size owing to the reduction of the confinement energy and the suppression of the electron-hole exchange interaction.
基金the National Key Research and Development Program of China (Grant No. 2016YFF02033604)the Guangdong Natural Science Foundation (Grant Nos. 2014A030310253, 2016A030310360)+2 种基金the Fundamental Research Funds for the Central Universities (Grant No. 2015ZM070)the National Natural Science Foundation of China (Grant No. 51602065)the Guangdong Science and Technology Plan (Grant Nos. 2016A040403037, 2016A010101026)
文摘The interlayer(IL) plays a vital role in hybrid white organic light-emitting diodes(WOLEDs); however,only a negligible amount of attention has been given to n-type ILs. Herein, the n-type IL, for the first time,has been demonstrated to achieve a high efficiency, high color rendering index(CRI), and low voltage trade-off.The device exhibits a maximum total efficiency of 41.5 lm W^(-1), the highest among hybrid WOLEDs with n-type ILs. In addition, high CRIs(80–88) at practical luminances(C1000 cd m^(-2)) have been obtained, satisfying the demand for indoor lighting. Remarkably, a CRI of 88 is the highest among hybrid WOLEDs. Moreover, the device exhibits low voltages, with a turn-on voltage of only 2.5 V([1 cd m^(-2)), which is the lowest among hybrid WOLEDs. The intrinsic working mechanism of the device has also been explored; in particular, the role of n-type ILs in regulating the distribution of charges and excitons has been unveiled. The findings demonstrate that the introduction of n-type ILs is effective in developing high-performance hybrid WOLEDs.
文摘Mass aggregations and migrations of millipedes despite numerous attempts to find causes for their occurrences are still an enigma. They have been reported from both southern and northern hemisphere countries, from highlands and lowlands of both tropical and temperate regions and they can involve species belonging to the orders Julida and Spirobolida, Polydesmida and Glomerida. According to the main suggestions put forward in the past, mass occurrences in Diplopoda occur：（1） because of a lack of food and a population increase beyond sustainable levels;（2） for the purpose of reproduction and in order to locate suitable oviposition sites;（3） to find overwintering or aestivation sites;（4） because of habitat disruption and changes in the local environment;（5） as a consequence of weather conditions the year（or winter and spring） before. A recent outbreak（November 2014） of a mass migration of the polydesmid Chamberlinius hualienensis Wang 1956 on the Japanese Izu Island of Hachijojima 300 km to the south of Tokyo gave this author an opportunity to review the existing literature on millipede mass migrations and to carry out additional observations on the phenomenon in the field as well as the laboratory. Hitherto unreported heavy infestations with phoretic deutonymphs of the mite Histiostoma sp. as well as dense populations of internal rhabditid nematodes（Oscheius cf. necromena and an unidentified species of the genus Fictor）, suggest that infestations of this kind could be necromenic and either have been a contributing factor for the mass migration or been a consequence of so manyindividuals occurring together at close proximity. It is concluded that mass migrations and aggregations in millipedes do not have one common cause, but represent phenomena that often are seasonally recurring events and appear identical in their outcome, but which have evolved as responses to different causes in different millipede taxa and therefore need to be examined on a case-to-case basis.
基金supported by a New Zealand University Grants Committee Scholarship
文摘During the regeneration of the tail in the arboreal New Zealand gecko （Hoplodactylus maculatus） a new set of tail scales, modified into pads bearing setae 5-20 μm long, is also regenerated. Stages of the formation of these specialized scales from epidermal pegs that invaginate the dermis of the regenerating tail are described on the basis of light and electron microscopic images. Within the pegs a differentiating clear layer interfaces with the spinulae and setae of the Oberh^utchen according to a process similar to that described for the digital pads. A layer of clear cytoplasm surrounds the growing tiny setae and eventually comities around them and their spatular ends, later leaving the new setae free- standing on the epidermal surface. The fresh adhesive pads help the gecko to maintain the prehensile function of its regenerated tail as together with the axial skeleton （made of a cylinder of elastic cartilage） the pads allow the regenerated tail to curl around twigs and small branches just like the original tail. The regeneration of caudal adhesive pads represents an ideal system to study the cellular processes that determine setal formation under normal or experimental manipulation as the progressive phases of the formation of the setae can be sequentially analyzed.
基金supported in part by the National Natural Science Foundation of China under Grant 62474149the Science and Technology Project of Fujian Province under Grant 2023H6038+2 种基金the Fujian Provincial Natural Science Foundation of China under Grant 2024J01052the Suzhou Integrated Circuit Advanced Packaging Substrate Technology Innovation Consortium under Grant LHT202329the Xiamen Science and Technology Plan Project under Grant 3502Z20241021.
文摘InGaN-based micro-light-emitting diodes(micro-LEDs)have been widely recognized as one of the critical technologies for high-resolution display applications.However,achieving high-efficiency,environmental-friendly,and small-size self-emitting InGaN-based red micro-LEDs present significant challenges that impede the progress of monolithically integrated III-nitride full-color micro-LED displays.Current limitations stem from insufficient control over carrier dynamics in InGaN multiple quantum wells(MQWs),where conventional structures exhibit severe efficiency degradation due to insufficient hole injection and defect-induced nonradiative recombination.Herein,spatially-resolved in-situ hyperspectral imaging and numerical simulations demonstrate that optimized V-pit promote the effectiveness of three-dimensional current pathways and facilitate localized electric field redistribution.This improvement enhances hole injection while suppressing nonradiative recombination,this work contributes to the microstructure design in InGaN-based red LEDs.
基金founded by SFR Cap Santé,Universitéde Reims Champagne-Ardenne,Reims,France to Aude-Marie Lepagnol-Bestel,a European Grant ERA-Net Cofund Action on Nanomedicine under Horizon 2020 Euronanomed 3(project MoDiaNo)CNES(Centre National d'Etudes Spatiales)grant(MemoBion)to Michel Simonneau.
文摘The autism susceptibility candidate 2(AUTS2)gene1,2 at 7q11.2 was first identified and found disrupted because of a balanced translocation in a pair of monozygotic twins with autism spectrum disorder(ASD).Analysis of 60 novel cases suggests that clinical phenotypes are more closely associated with intellectual disability rather than directly linked to ASD features.Human AUTS2 is a highly conserved gene that spans 1.2 Mb.Human AUTS2 protein has two major isoforms,full-length(1259 aa)and C-terminal(711 aa).Phenotypic analysis of patients indicated that they had borderline to severe intellectual disability/developmental delay,and 83%e100%had microcephaly.Mild dysmorphology was present.Specific traits of autism(like obsessive behavior)were seen frequently(83%).AUTS2 is also associated with alcohol consumption,heroin dependence,schizophrenia,and dyslexia,as analyzed using GWAS studies.
基金Science and Engineering Research Board(SIR/2022/00019,CRG/2021/00306)QuanTEduPAUSE.
文摘We propose and numerically test,to our knowledge,a novel concept for asymmetric vortex beam generation in a degenerate vertical external cavity surface emitting laser(DVECSEL).The method is based on a phase-locking ring array of lasers created inside a degenerate cavity with a binary amplitude mask containing circular holes.The diffraction engineering of the mask profile allows for controlling the complex coupling between the lasers.The asymmetry between different lasers is introduced by varying the hole diameters corresponding to different lasers.
基金the financial support in part from TUBITAK 20AG001,and 121C266HVD also acknowledges the support from TUBA and TUBITAK 2247-A National Leader Researchers Program(121C266)。
文摘Three-dimensional(3D)printing allows for the construction of complex structures.However,3D-printing vertical structures with a high aspect ratio remains a pending challenge,especially when a high lateral resolution is required.Here,to address this challenge,we propose and demonstrate micro-3D sculptured metastructures with deep trenches of 1:4(width:height)aspect ratio for sub-10µm resolution.Our construction relies on two-photon polymerization for a 3D-pattern with its trenches,followed by electroplating of a thick metal film and its dry etching to remove the seed layer.To test the proposed fabrication process,we built up three-dimensional RF metastructures showcasing the depth effect as the third dimension.Using the numerical solutions,we custom-tailored these metastructure resonators to fall within a specific resonance frequency range of 4-6 GHz while undertaking comparative analyses regarding overall footprint,quality factor,and resonance frequency shift as a function of their cross-sectional aspect ratio.The proposed process flow is shown to miniaturize metal footprint and tune the resonance frequency of these thick 3Dmetastructures while increasing their quality factor.These experimental findings indicate that this method of producing trenches via 3D-printing provides rich opportunities to implement high-aspect-ratio,complex structures.
基金supported by the National Natural Science Foundation of China under Grant Nos.51027006 and 50675017
文摘The fabrication deviation of prisms and the error crosstalk are two major factors that produce serious systematic errors in dual-beam roll measurement based on a rhombic prism, and an error compensation method is put forward in this letter to reduce these systematic errors. The rotation matrix, reflection matrix, and refraction matrix are used to calculate and obtain the mathematical relationship model of the roll angle as well as the fabrication deviation of prism and error crosstalk. The fabrication deviation can be obtained through comparison experiments and using the least square method. In this way, the systematic error of the roll measurement caused by fabrication deviation of prism and error crosstalk can be eliminated theoretically. The experimental results show that the maximum error of the roll angle measurement reduces evidently to 3.5″ from the previous 347.2″ after compensation.
基金the National Natural Science Foundation of China(51333007,91433201)the Ministry of Science and Technology of China(973 program No.2013CB834805)the Foundation of Jilin Research Council(2012ZDGG001)for the support of this research.
文摘Organic light-emitting diodes(OLEDs)are driven by injected charges from an anode and a cathode.The low and high work function metals are necessary for the effective injection of electrons and holes,respectively.Here,we introduce a fully novel design concept using organic semiconductor heterojunctions(OSHJs)as the charge injectors for achieving highly efficient OLEDs,regardless of the work functions of the electrodes.In contrast to traditional injected charges from the electrodes,the injected charges originate from the OSHJs.The device performance was shown to be significantly improved in efficiency and stability compared to conventional OLEDs.Attractively,the OLEDs based on OSHJs as charge injectors still exhibited an impressive performance when the low work function Al was replaced by air-and chemistry-stable high work function metals,such as Au,Ag,and Cu,as the cathode contact,which has been suggested to be difficult in conventional OLEDs.This concept challenges the conventional design approach for the injection of charges and allows for the realization of practical applications of OLEDs with respect to high efficiency,selectable electrodes,and a long lifetime.
文摘We report high-efficiency CdTe/CdS core/shell nanocrystals synthesized in water by epitaxially growing CdS shells on aqueous CdTe cores at room temperature,enabled by the controlled release of S species under low-intensity ultraviolet(UV)light illumination.The resulting photo-induced dissociation of S2O2-ions conveniently triggers the formation of critical two-dimensional CdS epitaxy on the CdTe surface at room temperature,as opposed to initiating the growth of individual CdS core-only nanocrystals.This controlled colloidal hetero-epitaxy leads to a substantial increase in the photoluminescence(PL)quantum yield(QY)of the shelled nanocrystals in water(reaching 64%).With a systematic set of studies,the maximum PL QY is found to be almost independent of the illuminating UV intensity,while the shell formation kinetics required for reaching the maximum QY linearly depends on the illuminating UV intensity.A stability study of the QD films in air at various temperatures shows highly improved thermal stability of the shelled QDs(up to 120℃in ambient air).These results indicate that the proposed aqueous CdTe/CdS core/shell nanocrystals hold great promise for applications requiring efficiency and stability.
基金G.J.acknow ledges the China Scholarship Council(No.201706740088).This work was partly supported by the bilateral IB-BMBF-TOBITAK Project ColMiBack(01DL20002)and DFG project EY 16/14-3.O.E.acknowledges TOBITAK for the financial support through BIDEB-2211 program.H.V.D.gratefully acknowledges support from TUBA.The use of the HZDR Ion Beam Center TEM facilities and the funding of TEM Talos by the German Federal Ministry of Education of Research(BMBF),Grant No.03SF0451,in the framework o f HEMCP are acknowledged.M.G.acknowledges the Swiss National Science Foundation(SNF)and the German Research Foundation(DFG EY 16/18-2)for financial support.W.W.received supports from Jiangsu Overseas Visiting Scholar Program for University Prom inent Young&Middle-aged Teachers and Presidents.X.F.acknowledges the China Scholarship Council(No.201606340161).J.W.received supports from the National Natural Science Foundation of China(No.21701143).We are very grateful to Prof.A lexander Eychmuller,Dr.Vladim ir Lesnyak and Dr.Alexey Shavel for the valuable discussions.We are grateful to Susanne Goldberg for TEM imaging,Franziska Eichler for the instruction to the PL decay measurements.We appreciate Linlin Wang and Dr.Juliane Simmchen for their help with DLS measurements.We thank Dr.Andre Wolf for his corrections to the draft.
文摘The application of polymers to replace oleylamine(OLA)and oleic acid(OA)as ligands for perovskite nanocrystals is an effective strategy to improve their stability and durability especially for the solution-based processing.Herein,we report a mechanosynthesis of lead bromide perovskite nanoparticles(NPs)stabilized by partially hydrolyzed poly(methyl methacrylate)(h-PMMA)and highmolecular-weight highly-branched poly(ethylenimine)(PEI-25K).The as-synthesized NP solutions exhibited green emission centered at 516 nm,possessing a narrow full-width at half-maximum of 17 nm and as high photoluminescence quantum yield(PL QY)as 85%,while showing excellent durability and resistance to polar solvents,e.g.,methanol.The colloids of polymer-stabilized NPs were directly processable toform stable and strongly-emitting thin films and solids,making them attractive as gain media.Furthermore,the roles of h-PMMA and PEI-25K in the grinding process were studied in depth.The h-PMMA can form micelles in the grinding solvent of dichloromethane to act as size-regulating templates for the growth of NPs.The PEI-25K with large amounts of amino groups induced significant enrichment of PbBr_(2)in the reaction mixture,which in turn caused the formation of CsPb_(2)Br_(5)-mPbBr_(2)and CsPbBr_(3)-Cs_(4)PbBr_(6)-nCsBr NPs.The presence of CsPbBr_(3)-Cs_(4)PbBr_(6)-nCsBr NPs was responsible for the high PL QY,as the Cs_(4)PbBr_(6)phase with a wide energy bandgap can passivate the surface defects of the CsPbBr_(3)phase.This work describes a direct and facile mechanosynthesis of polymer-coordinated perovskite NPs and promotes in-depth understanding of the formation and phase conversion for perovskite NPs in the grinding process.
基金Agency for Science,Technology and Research,Grant/Award Number:1527300025Central University Basic Research Fund of China,Grant/Award Numbers:020514380231,021014380177+5 种基金National Natural Science Foundation of China,Grant/Award Numbers:12104006,21873048,92056204National Research Foundation,Grant/Award Number:NRFNRFI2016-08Natural Science Foundation of Jiangsu Province,Grant/Award Number:BK20180319Start up fundations from Anhui UniversityTsinghua UniversityState Key Laboratory of Low-Dimensional Quantum Physics。
文摘Van der Waals heterojunctions are fast-emerging quantum structures fabricated by the controlled stacking of two-dimensional(2D)materials.Owing to the atomically thin thickness,their carrier properties are not only determined by the host material itself,but also defined by the interlayer interactions,including dielectric environment,charge trapping centers,and stacking angles.The abundant constituents without the limitation of lattice constant matching enable fascinating electrical,optical,and magnetic properties in van der Waals heterojunctions toward next-generation devices in photonics,optoelectronics,and information sciences.This review focuses on the charge and energy transfer processes and their dynamics in transition metal dichalcogenides(TMDCs),a family of quantum materials with strong excitonic effects and unique valley properties,and other related 2D materials such as graphene and hexagonalboron nitride.In the first part,we summarize the ultrafast charge transfer processes in van der Waals heterojunctions,including its experimental evidence and theoretical understanding,the interlayer excitons at the TMDC interfaces,and the hot carrier injection at the graphene/TMDCs interface.In the second part,the energy transfer,including both Förster and Dexter types,are reviewed from both experimental and theoretical perspectives.Finally,we highlight the typical charge and energy transfer applications in photodetectors and summarize the challenges and opportunities for future development in this field.
文摘A BP/CdS heterostructure-based artificial photonic synapse with an ultra-low power consumption is proposed,presenting great potential in high-performance neuromorphic vision systems.
基金financial support from DIM Respore,Region Ile de France(PhD grants),ANR Epsilomics(No.17-CE09-0044-02)CY Initiative of Excellence(“Investissements d’Avenir”No.ANR16-IDEX-0008)Réseau sur le Stockage Electrochimique de l’Energie(RS2E).
文摘With an increasing global population that is rapidly ageing,our society faces challenges that impact health,environment,and energy demand.With this ageing comes an accumulation of cellular changes that lead to the development of diseases and susceptibility to infections.This impacts not only the health system,but also the global economy.As the population increases,so does the demand for energy and the emission of pollutants,leading to a progressive degradation of our environment.This in turn impacts health through reduced access to arable land,clean water,and breathable air.New monitoring approaches to assist in environmental control and minimize the impact on health are urgently needed,leading to the development of new sensor technologies that are highly sensitive,rapid,and low-cost.Nanopore sensing is a new technology that helps to meet this purpose,with the potential to provide rapid point-of-care medical diagnosis,real-time on-site pollutant monitoring systems to manage environmental health,as well as integrated sensors to increase the efficiency and storage capacity of renewable energy sources.In this review we discuss how the powerful approach of nanopore based single-molecule,or particle,electrical promises to overcome existing and emerging societal challenges,providing new opportunities and tools for personalized medicine,localized environmental monitoring,and improved energy production and storage systems.
