The crossmodal interaction of different senses,which is an important basis for learning and memory in the human brain,is highly desired to be mimicked at the device level for developing neuromorphic crossmodal percept...The crossmodal interaction of different senses,which is an important basis for learning and memory in the human brain,is highly desired to be mimicked at the device level for developing neuromorphic crossmodal perception,but related researches are scarce.Here,we demonstrate an optoelectronic synapse for vision-olfactory crossmodal perception based on MXene/violet phosphorus(VP)van der Waals heterojunctions.Benefiting from the efficient separation and transport of photogenerated carriers facilitated by conductive MXene,the photoelectric responsivity of VP is dramatically enhanced by 7 orders of magnitude,reaching up to 7.7 A W^(−1).Excited by ultraviolet light,multiple synaptic functions,including excitatory postsynaptic currents,pairedpulse facilitation,short/long-term plasticity and“learning-experience”behavior,were demonstrated with a low power consumption.Furthermore,the proposed optoelectronic synapse exhibits distinct synaptic behaviors in different gas environments,enabling it to simulate the interaction of visual and olfactory information for crossmodal perception.This work demonstrates the great potential of VP in optoelectronics and provides a promising platform for applications such as virtual reality and neurorobotics.展开更多
Two-dimension(2D)van der Waals heterojunction holds essential promise in achieving high-performance flexible near-infrared(NIR)photodetector.Here,we report the successful fabrication of ZnSb/Ti_(3)C_(2)T_(x)MXene base...Two-dimension(2D)van der Waals heterojunction holds essential promise in achieving high-performance flexible near-infrared(NIR)photodetector.Here,we report the successful fabrication of ZnSb/Ti_(3)C_(2)T_(x)MXene based flexible NIR photodetector array via a facile photolithography technology.The single ZnSb/Ti_(3)C_(2)T_(x)photodetector exhibited a high light-to-dark current ratio of 4.98,fast response/recovery time(2.5/1.3 s)and excellent stability due to the tight connection between 2D ZnSb nanoplates and 2D Ti_(3)C_(2)T_(x)MXene nanoflakes,and the formed 2D van der Waals heterojunction.Thin polyethylene terephthalate(PET)substrate enables the ZnSb/Ti_(3)C_(2)T_(x)photodetector withstand bending such that stable photoelectrical properties with non-obvious change were maintained over 5000 bending cycles.Moreover,the ZnSb/Ti_(3)C_(2)T_(x)photodetectors were integrated into a 26×5 device array,realizing a NIR image sensing application.展开更多
Covalent organic frameworks(COFs)have emerged as a kind of rising star materials in photocatalysis.However,their photocatalytic activities are restricted by the high photogenerated electron-hole pairs recombination ra...Covalent organic frameworks(COFs)have emerged as a kind of rising star materials in photocatalysis.However,their photocatalytic activities are restricted by the high photogenerated electron-hole pairs recombination rate.Herein,a novel metal-free 2D/2D van der Waals heterojunction,composed of a two-dimensional(2D)COF with ketoenamine linkage(TpPa-1-COF)and 2D defective hexagonal boron nitride(h-BN),is successfully constructed through in situ solvothermal method.Benefitting from the presence of VDW heterojunction,larger contact area and intimate electronic coupling can be formed between the interface of TpPa-1-COF and defective h-BN,which make contributions to promoting charge car-riers separation.The introduced defects can also endow the h-BN with porous structure,thus providing more reactive sites.Moreover,the TpPa-1-COF will undergo a structural transformation after being integrated with defective h-BN,which can enlarge the gap between the conduction band position of the h-BN and TpPa-1-COF,and suppress electron backflow,corroborated by experimental and density functional theory calculations results.Accordingly,the resulting porous h-BN/TpPa-1-COF metal-free VDW heterojunction displays out-standing solar energy catalytic activity for water splitting without co-catalysts,and the H_(2) evolution rate can reach up to 3.15 mmol g^(−1) h^(−1),which is about 67 times greater than that of pristine TpPa-1-COF,also surpassing that of state-of-the-art metal-free-based photocatalysts reported to date.In particular,it is the first work for constructing COFs-based heterojunctions with the help of h-BN,which may provide new avenue for designing highly efficient metal-free-based photocatalysts for H_(2) evolution.展开更多
Van der Waals(VDW)heterojunctions in a 2D/2D contact provide the highest area for the separation and transfer of charge carriers.In this work,a top-down strategy with a gas erosion process was employed to fabricate a ...Van der Waals(VDW)heterojunctions in a 2D/2D contact provide the highest area for the separation and transfer of charge carriers.In this work,a top-down strategy with a gas erosion process was employed to fabricate a 2D/2D carbon nitride VDW heterojunction in carbon nitride(g-C_(3)N_(4))with carbon-rich carbon nitride.The created 2D semiconducting channel in the VDW structure exhibits enhanced electric field exposure and radiation absorption,which facilitates the separation of the charge carriers and their mobility.Consequently,compared with bulk g-C_(3)N_(4)and its nanosheets,the photocatalytic performance of the fabricated carbon nitride VDW heterojunction in the water splitting reaction to hydrogen is improved by 8.6 and 3.3 times,respectively,while maintaining satisfactory photo-stability.Mechanistically,the finite element method(FEM)was employed to evaluate and clarify the contributions of the formation of VDW heterojunction to enhanced photocatalysis,in agreement quantitatively with experimental ones.This study provides a new and effective strategy for the modification and more insights to performance improvement on polymeric semiconductors in photocatalysis and energy conversion.展开更多
Investigations of two-dimensional(2D)/one-dimensional(1D)van der Waals(vdW)heterojunctions have attracted significant attention due to their excellent properties such as the smooth heterointerface,the highly gate-tuna...Investigations of two-dimensional(2D)/one-dimensional(1D)van der Waals(vdW)heterojunctions have attracted significant attention due to their excellent properties such as the smooth heterointerface,the highly gate-tunable bandgap,and the ultrafast carrier transport.However,the complicated method of manufacturing vdW heterojunction represents a major problem that severely limits their practical applications.Herein,we develop one-step hydrothermal method and use it to synthesize 2D PbI_(2)/1D Pb_(5)S_(2)I_(6)vdW heterojunction.The PbI_(2)/Pb_(5)S_(2)I_(6)vdW heterojunction photodetector(PD)displays lower dark current(<20 pA),higher responsivity(up to 134 mA·W-1),self-powered and wider response spectrum in comparison with that of pristine PbI_(2)PD and Pb_(5)S_(2)I_(6)PD.This one-step hydrothermal method provides a new idea for preparing other mixed-dimensional heterojunction.展开更多
Organic/inorganic hybrid van der Waals heterostructure with an atomically abrupt interface has attracted great research interests within the field of multifunctional electronic and optoelectronic devices.The integrati...Organic/inorganic hybrid van der Waals heterostructure with an atomically abrupt interface has attracted great research interests within the field of multifunctional electronic and optoelectronic devices.The integration of organic rubrene films with inorganic Si semiconductors can avoid the atomic mutual-diffusion at the interface,and provide the possibility of forming two-dimensional van der Waals heterojunction accompanied with the type-II energy band alignment,due to the transfer behaviors of majority carriers at the interface.In this study,the high-quality rubrene/Si van der Waals heterostructure with an electronically abrupt junction was prepared,and a self-powered photodetector was then constructed based on this hybrid heterojunction.The photodetector demonstrated an excellent switching response to the 1064 nm monochromatic light with large on/off current ratio of 7.0×10^(3),the maximum photocurrent of 14.62 m A,the maximum responsivity of 2.07 A/W,the maximum detectivity of 2.9×10^(11)Jones,and a fast response time of 13.0μs.This study offers important guidance for preparing high-quality rubrene/Si hybrid van der Waals heterostructure with desirable band alignment,and the designed heterojunction photodetector has an important application prospect in the field of multifunctional optoelectronics.展开更多
The heterojunction integration of two-dimensional(2D)materials via van der Waals(vdW)forces,unencumbered by lattice and processing constraints,constitutes an efficacious approach to enhance the overall optoelectronic ...The heterojunction integration of two-dimensional(2D)materials via van der Waals(vdW)forces,unencumbered by lattice and processing constraints,constitutes an efficacious approach to enhance the overall optoelectronic performance of photodetectors,due to an assortment of distinctive light-matter interactions.Nonetheless,vdW heterojunction photodetectors based on transition metal dichalcogenides(TMDs)face an inevitable trade-off between low dark currents and high responsivity,curtailing the application potential of myriad novel optoelectronic components in sensing,spectral,and communication systems.In this study,we present the successful actualization of a highly sensitive,self-powered,and gate-tunable bipolar response photodetector.The mechanisms underlying photocurrent generation were scrutinized via bias-,power-,and position-dependent mapping photoresponse measurements,identifying the photovoltaic effect,which is attributable to the Schottky junction’s built-in electric field,as the predominant mechanism.The prototype Au-WS2-graphene photodetector exhibits a remarkable light on/off ratio of 1.2×10^(6),a specific detectivity of 6.12×10^(11)cm H^(z1/2)W^(-1)with 20μs response time at 638 nm.The wide gate-tunable responsivity provides an adjustability scope,ranging from 0.9 to 3.1 A W^(-1).Notably,the device demonstrates an exceptional linear photocurrent response,with a linear dynamic range(LDR)value approximating 130 dB,which significantly surpasses that of other photodetectors based on TMDs.展开更多
Two-dimensional(2D) atomic crystals,such as graphene,black phosphorus(BP) and transition metal dichalcogenides(TMDCs) are attractive for use in optoelectronic devices,due to their unique crystal structures and optical...Two-dimensional(2D) atomic crystals,such as graphene,black phosphorus(BP) and transition metal dichalcogenides(TMDCs) are attractive for use in optoelectronic devices,due to their unique crystal structures and optical absorption properties.In this study,we fabricated BP/ReS2 van der Waals(vdWs) heterojunction devices.The devices realized broadband photoresponse from visible to near infrared(NIR)(400–1800 nm) with stable and repeatable photoswitch characteristics,and the photoresponsivity reached 1.8 mA/W at 1550 nm.In addition,the polarization sensitive detection in the visible to NIR spectrum(532–1750 nm) was demonstrated,and the photodetector showed a highly polarization sensitive photocurrent with an anisotropy ratio as high as 6.44 at 1064 nm.Our study shows that van der Waals heterojunction is an effective way to realize the broadband polarization sensitive photodetection,which is of great significance to the realization and application of multi-functional devices based on 2D vdWs heterostructures.展开更多
Based on first-principles simulations,we revisit the crystal structures,electronic structures,and structural stability of the layered transition metal dichalcogenides(TMDCs)NbS2,and shed more light on the crucial role...Based on first-principles simulations,we revisit the crystal structures,electronic structures,and structural stability of the layered transition metal dichalcogenides(TMDCs)NbS2,and shed more light on the crucial roles of the van der Waals(vdW)interactions.Theoretically calculated results imply that the vdW corrections are important to reproduce the layered crystal structure,which is significant to correctly describe the electronic structure of NbS2.More interestingly,under hydrostatic pressure or tensile strain in ab plane,an isostructural phase transition from two-dimensional layered structure to three-dimensional bulk in the I4/mmm phase has been uncovered.The abnormal structural transition is closely related to the electronic structure instability and interlayer bonding effects.The interlayer Nb-S distances collapse and the interlayer vdW interactions disappear,concomitant with new covalent bond emerging and increasing coordination number.Present work highlights the significance of the vdW interactions,and provides new insights on the unconventional structural transitions in NbS2,which will attract wide audience working in the hectic field of TMDCs.展开更多
Black phosphorene(BP)and its analogs have attracted intensive attention due to their unique puckered structures,anisotropic characteristics,and negative Poisson’s ratio.The van der Waals(vdW)heterostructures assembly...Black phosphorene(BP)and its analogs have attracted intensive attention due to their unique puckered structures,anisotropic characteristics,and negative Poisson’s ratio.The van der Waals(vdW)heterostructures assembly by stacking different materials show novel physical properties,however,the parent materials do not possess.In this work,the first-principles calculations are performed to study the mechanical properties of the vdW heterostructure.Interestingly,a near-zero Poisson’s ratio ν_(zx)is found in BP/SnSe heterostructure.In addition,compared with the parent materials BP and SnSe with strong in-plane anisotropic mechanical properties,the BP/SnSe heterostructure shows strongly suppressed anisotropy.The results show that the vdW heterostructure has quite different mechanical properties compared with the parent materials,and provides new opportunities for the mechanical applications of the heterostructures.展开更多
Two-dimensional(2D)layered materials have been considered promising candidates for next-generation optoelectronics.However,the performance of 2D photodetectors still has much room for improvement due to weak light abs...Two-dimensional(2D)layered materials have been considered promising candidates for next-generation optoelectronics.However,the performance of 2D photodetectors still has much room for improvement due to weak light absorption of planar 2D materials and lack of high-quality heterojunction preparation technology.Notably,2D materials integrating with mature bulk semiconductors are a promising pathway to overcome this limitation and promote the practical application on optoelectronics.In this work,we present the patterned assembly of MoSe_(2)/pyramid Si mixed-dimensional van der Waals(vdW)heterojunction arrays for broadband photodetection and imaging.Benefited from the light trapping effect induced enhanced optical absorption and high-quality vdW heterojunction,the photodetector demonstrates a wide spectral response range from 265 to 1550 nm,large responsivity up to 0.67 A·W^(-1),high specific detectivity of 1.84×10^(13)Jones,and ultrafast response time of 0.34/5.6μs at 0 V.Moreover,the photodetector array exhibits outstanding broadband image sensing capability.This study offers a novel development route for high-performance and broadband photodetector array by MoSe_(2)/pyramid Si mixed-dimensional heterojunction.展开更多
The design of van der Waals heterojunctions with S-scheme charge transfer pathway is expected to be an effective strategy for improvement of photocatalytic performance.Herein,two-dimensional(2D)phosphorus-doped g-C_(3...The design of van der Waals heterojunctions with S-scheme charge transfer pathway is expected to be an effective strategy for improvement of photocatalytic performance.Herein,two-dimensional(2D)phosphorus-doped g-C_(3)N_(4)/Bi_(5)O_(7)Ivan der Waals heterojunctions with reduced graphene oxide as electron bridge(PCN/RGO/Bi_(5O)_(7)I)were successfully synthesized via hydrothermal method.The van der Waals interaction endowed 2D PCN/RGO/Bi_(5O)_(7)I with intimate contact interface,lattice match,tunable band structure,and internal electric field,which efficiently promoted interfacial charge separation and enhanced redox ability of photogenerated charge carriers.As a result,the S-scheme PCN/RGO/Bi_5O_7I van der Waals heterojunctions exhibited superior photocatalytic performance in ciprofloxacin degradation and real pharmaceutical wastewater treatment.The optimized 12%PCN/RGO/Bi_5O_7I displayed the highest photocatalytic activity with 92%removal of ciprofloxacin.Importantly,the COD removal efficiency and extent of mineralization of real pharmaceutical wastewater reached 66.9%and 59.8%,respectively,and the biodegradability of pharmaceutical wastewater was significantly improved.The photocatalytic mechanism of the S-scheme PCN/RGO/Bi_(5)O_(7)I van der Waals heterojunctions based on the analysis of reactive species,work function,and internal electric field was presented.This study provides fresh insights into plausible design of S-scheme van der Waals heterojunction to enhance photocatalytic redox ability.展开更多
Mixed-dimensional van der Waals(vdW)heterostructures based on two-dimensional transition metal dichalcogenides and threedimensional semiconductors have led to a new era in next-generation optoelectronics due to the hi...Mixed-dimensional van der Waals(vdW)heterostructures based on two-dimensional transition metal dichalcogenides and threedimensional semiconductors have led to a new era in next-generation optoelectronics due to the high-quality interfaces and energy band complementation,especially in broadband photodetectors which can be used for all-weather navigation,object identification,etc.However,the reported photodetectors conventionally operated in photodiode mode with low responsivity and a narrow response spectrum.In this study,we report a p-WSe_(2)/n-Ge vdW heterojunction phototransistor with a Schottky barrier collector on n-Ge for broadband photodetection.Large hole/electron injection ratio from p-WSe_(2)/n-Ge heterojunction under forward bias due to their large bandgap offset renders the high photocurrent gain,while the Ge Schottky barrier limits the dark current.The responsivities of the phototransistor at 1.0 V emitter-collector bias are 55,95,and 120 A·W−1 at 405,1,310,and 1,550 nm,respectively,which is superior to that of the corresponding p-WSe_(2)/n-Ge photodiodes.The phototransistor shows a high photocurrent gain of 80,a specific detectivity of 1011 Jones,as well as a fast response time of 290μs at 1,550 nm.The results suggest that the novel phototransistor being implemented with complementary metal-oxide-semiconductor processing is an ideal strategy for high-performance broadband photodetection.展开更多
基金supported by National Natural Science Foundation of China(No.51902250).
文摘The crossmodal interaction of different senses,which is an important basis for learning and memory in the human brain,is highly desired to be mimicked at the device level for developing neuromorphic crossmodal perception,but related researches are scarce.Here,we demonstrate an optoelectronic synapse for vision-olfactory crossmodal perception based on MXene/violet phosphorus(VP)van der Waals heterojunctions.Benefiting from the efficient separation and transport of photogenerated carriers facilitated by conductive MXene,the photoelectric responsivity of VP is dramatically enhanced by 7 orders of magnitude,reaching up to 7.7 A W^(−1).Excited by ultraviolet light,multiple synaptic functions,including excitatory postsynaptic currents,pairedpulse facilitation,short/long-term plasticity and“learning-experience”behavior,were demonstrated with a low power consumption.Furthermore,the proposed optoelectronic synapse exhibits distinct synaptic behaviors in different gas environments,enabling it to simulate the interaction of visual and olfactory information for crossmodal perception.This work demonstrates the great potential of VP in optoelectronics and provides a promising platform for applications such as virtual reality and neurorobotics.
基金supported by National Natural Science Foundation of China(51672308,51972025,61888102,and 62004187).
文摘Two-dimension(2D)van der Waals heterojunction holds essential promise in achieving high-performance flexible near-infrared(NIR)photodetector.Here,we report the successful fabrication of ZnSb/Ti_(3)C_(2)T_(x)MXene based flexible NIR photodetector array via a facile photolithography technology.The single ZnSb/Ti_(3)C_(2)T_(x)photodetector exhibited a high light-to-dark current ratio of 4.98,fast response/recovery time(2.5/1.3 s)and excellent stability due to the tight connection between 2D ZnSb nanoplates and 2D Ti_(3)C_(2)T_(x)MXene nanoflakes,and the formed 2D van der Waals heterojunction.Thin polyethylene terephthalate(PET)substrate enables the ZnSb/Ti_(3)C_(2)T_(x)photodetector withstand bending such that stable photoelectrical properties with non-obvious change were maintained over 5000 bending cycles.Moreover,the ZnSb/Ti_(3)C_(2)T_(x)photodetectors were integrated into a 26×5 device array,realizing a NIR image sensing application.
基金supported by the National Natural Science Foundation of China(Nos.22101105,52071171,52202248)the Research Fund for the Doctoral Program of Liaoning Province(2021-BS-086)+6 种基金Liaoning BaiQianWan Talents Program(LNBQW2018B0048)Shenyang Science and Technology Project(21-108-9-04)Australian Research Council(ARC)through Future Fellowship(FT210100298,FT210100806)Discovery Project(DP220100603)Linkage Project(LP210100467,LP210200504,LP210200345,LP220100088)Industrial Transformation Training Centre(IC180100005)schemesthe Australian Government through the Cooperative Research Centres Projects(CRCPXIII000077).
文摘Covalent organic frameworks(COFs)have emerged as a kind of rising star materials in photocatalysis.However,their photocatalytic activities are restricted by the high photogenerated electron-hole pairs recombination rate.Herein,a novel metal-free 2D/2D van der Waals heterojunction,composed of a two-dimensional(2D)COF with ketoenamine linkage(TpPa-1-COF)and 2D defective hexagonal boron nitride(h-BN),is successfully constructed through in situ solvothermal method.Benefitting from the presence of VDW heterojunction,larger contact area and intimate electronic coupling can be formed between the interface of TpPa-1-COF and defective h-BN,which make contributions to promoting charge car-riers separation.The introduced defects can also endow the h-BN with porous structure,thus providing more reactive sites.Moreover,the TpPa-1-COF will undergo a structural transformation after being integrated with defective h-BN,which can enlarge the gap between the conduction band position of the h-BN and TpPa-1-COF,and suppress electron backflow,corroborated by experimental and density functional theory calculations results.Accordingly,the resulting porous h-BN/TpPa-1-COF metal-free VDW heterojunction displays out-standing solar energy catalytic activity for water splitting without co-catalysts,and the H_(2) evolution rate can reach up to 3.15 mmol g^(−1) h^(−1),which is about 67 times greater than that of pristine TpPa-1-COF,also surpassing that of state-of-the-art metal-free-based photocatalysts reported to date.In particular,it is the first work for constructing COFs-based heterojunctions with the help of h-BN,which may provide new avenue for designing highly efficient metal-free-based photocatalysts for H_(2) evolution.
基金the National Natural Science Foundation of China(51676096)supported by the Australian Research Council(DP170104264 and DP190103548).
文摘Van der Waals(VDW)heterojunctions in a 2D/2D contact provide the highest area for the separation and transfer of charge carriers.In this work,a top-down strategy with a gas erosion process was employed to fabricate a 2D/2D carbon nitride VDW heterojunction in carbon nitride(g-C_(3)N_(4))with carbon-rich carbon nitride.The created 2D semiconducting channel in the VDW structure exhibits enhanced electric field exposure and radiation absorption,which facilitates the separation of the charge carriers and their mobility.Consequently,compared with bulk g-C_(3)N_(4)and its nanosheets,the photocatalytic performance of the fabricated carbon nitride VDW heterojunction in the water splitting reaction to hydrogen is improved by 8.6 and 3.3 times,respectively,while maintaining satisfactory photo-stability.Mechanistically,the finite element method(FEM)was employed to evaluate and clarify the contributions of the formation of VDW heterojunction to enhanced photocatalysis,in agreement quantitatively with experimental ones.This study provides a new and effective strategy for the modification and more insights to performance improvement on polymeric semiconductors in photocatalysis and energy conversion.
基金National Natural Science Foundation of China(No.61376017)。
文摘Investigations of two-dimensional(2D)/one-dimensional(1D)van der Waals(vdW)heterojunctions have attracted significant attention due to their excellent properties such as the smooth heterointerface,the highly gate-tunable bandgap,and the ultrafast carrier transport.However,the complicated method of manufacturing vdW heterojunction represents a major problem that severely limits their practical applications.Herein,we develop one-step hydrothermal method and use it to synthesize 2D PbI_(2)/1D Pb_(5)S_(2)I_(6)vdW heterojunction.The PbI_(2)/Pb_(5)S_(2)I_(6)vdW heterojunction photodetector(PD)displays lower dark current(<20 pA),higher responsivity(up to 134 mA·W-1),self-powered and wider response spectrum in comparison with that of pristine PbI_(2)PD and Pb_(5)S_(2)I_(6)PD.This one-step hydrothermal method provides a new idea for preparing other mixed-dimensional heterojunction.
基金the National Natural Science Foundation of China(Grant Nos.11604228,11774208,and 11974222)the Science and Technology Planning Foundation of Shandong Province,China(Grant No.J18KA219)。
文摘Organic/inorganic hybrid van der Waals heterostructure with an atomically abrupt interface has attracted great research interests within the field of multifunctional electronic and optoelectronic devices.The integration of organic rubrene films with inorganic Si semiconductors can avoid the atomic mutual-diffusion at the interface,and provide the possibility of forming two-dimensional van der Waals heterojunction accompanied with the type-II energy band alignment,due to the transfer behaviors of majority carriers at the interface.In this study,the high-quality rubrene/Si van der Waals heterostructure with an electronically abrupt junction was prepared,and a self-powered photodetector was then constructed based on this hybrid heterojunction.The photodetector demonstrated an excellent switching response to the 1064 nm monochromatic light with large on/off current ratio of 7.0×10^(3),the maximum photocurrent of 14.62 m A,the maximum responsivity of 2.07 A/W,the maximum detectivity of 2.9×10^(11)Jones,and a fast response time of 13.0μs.This study offers important guidance for preparing high-quality rubrene/Si hybrid van der Waals heterostructure with desirable band alignment,and the designed heterojunction photodetector has an important application prospect in the field of multifunctional optoelectronics.
基金supported by the National Natural Science Foundation of China(Grant Nos.62305077,62222514,61991440,and 62005249)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.Y2021070)+8 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB43010200)Shanghai Rising-Star Program(Grant No.20QA1410400)Shanghai Science and Technology Committee(Grant Nos.23ZR1482000,20JC1416000,and 22JC1402900)the Natural Science Foundation of Zhejiang Province(Grant No.LR22F050004)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Hangzhou West Science and Technology Innovation Corridor Youth ProjectExcellent Postdoctoral Research Projects of Zhejiang Province(Grant No.ZJ2021019)the Open Fund of State Key Laboratory of Infrared Physics(Grant No.SITP-NLIST-YB-2023-13)Zhejiang Provincial Natural Science Foundation(Grant No.LQ20F050005)。
文摘The heterojunction integration of two-dimensional(2D)materials via van der Waals(vdW)forces,unencumbered by lattice and processing constraints,constitutes an efficacious approach to enhance the overall optoelectronic performance of photodetectors,due to an assortment of distinctive light-matter interactions.Nonetheless,vdW heterojunction photodetectors based on transition metal dichalcogenides(TMDs)face an inevitable trade-off between low dark currents and high responsivity,curtailing the application potential of myriad novel optoelectronic components in sensing,spectral,and communication systems.In this study,we present the successful actualization of a highly sensitive,self-powered,and gate-tunable bipolar response photodetector.The mechanisms underlying photocurrent generation were scrutinized via bias-,power-,and position-dependent mapping photoresponse measurements,identifying the photovoltaic effect,which is attributable to the Schottky junction’s built-in electric field,as the predominant mechanism.The prototype Au-WS2-graphene photodetector exhibits a remarkable light on/off ratio of 1.2×10^(6),a specific detectivity of 6.12×10^(11)cm H^(z1/2)W^(-1)with 20μs response time at 638 nm.The wide gate-tunable responsivity provides an adjustability scope,ranging from 0.9 to 3.1 A W^(-1).Notably,the device demonstrates an exceptional linear photocurrent response,with a linear dynamic range(LDR)value approximating 130 dB,which significantly surpasses that of other photodetectors based on TMDs.
基金supported by the National Key R&D Program of China (Grant No. 2017YFA0303400 and No.2017YFB 0405700)supported by the NSFC Grant Nos. 61774144 and 11474272sponsored by Chinese Academy of Sciences, grant No. QYZDY-SSW-JSC020, XDPB12, and XDB28000000
文摘Two-dimensional(2D) atomic crystals,such as graphene,black phosphorus(BP) and transition metal dichalcogenides(TMDCs) are attractive for use in optoelectronic devices,due to their unique crystal structures and optical absorption properties.In this study,we fabricated BP/ReS2 van der Waals(vdWs) heterojunction devices.The devices realized broadband photoresponse from visible to near infrared(NIR)(400–1800 nm) with stable and repeatable photoswitch characteristics,and the photoresponsivity reached 1.8 mA/W at 1550 nm.In addition,the polarization sensitive detection in the visible to NIR spectrum(532–1750 nm) was demonstrated,and the photodetector showed a highly polarization sensitive photocurrent with an anisotropy ratio as high as 6.44 at 1064 nm.Our study shows that van der Waals heterojunction is an effective way to realize the broadband polarization sensitive photodetection,which is of great significance to the realization and application of multi-functional devices based on 2D vdWs heterostructures.
基金Project supported by the National Natural Science Foundation of China(Grant No.11864008)Guangxi Natural Science Foundation,China(Grant Nos.2018GXNSFAA138185 and 2018AD19200)High performance computational resources provided by LvLiang Cloud Computing Center of China and National Supercomputer Center on TianHe-2 are gratefully acknowledged.
文摘Based on first-principles simulations,we revisit the crystal structures,electronic structures,and structural stability of the layered transition metal dichalcogenides(TMDCs)NbS2,and shed more light on the crucial roles of the van der Waals(vdW)interactions.Theoretically calculated results imply that the vdW corrections are important to reproduce the layered crystal structure,which is significant to correctly describe the electronic structure of NbS2.More interestingly,under hydrostatic pressure or tensile strain in ab plane,an isostructural phase transition from two-dimensional layered structure to three-dimensional bulk in the I4/mmm phase has been uncovered.The abnormal structural transition is closely related to the electronic structure instability and interlayer bonding effects.The interlayer Nb-S distances collapse and the interlayer vdW interactions disappear,concomitant with new covalent bond emerging and increasing coordination number.Present work highlights the significance of the vdW interactions,and provides new insights on the unconventional structural transitions in NbS2,which will attract wide audience working in the hectic field of TMDCs.
基金Project supported by the National Natural Science Foundation of China(Nos.11572040 and92163101)the National Key Research and Development Program of China(No.2019YFA0307900)the Beijing Natural Science Foundation(No.Z190011)。
文摘Black phosphorene(BP)and its analogs have attracted intensive attention due to their unique puckered structures,anisotropic characteristics,and negative Poisson’s ratio.The van der Waals(vdW)heterostructures assembly by stacking different materials show novel physical properties,however,the parent materials do not possess.In this work,the first-principles calculations are performed to study the mechanical properties of the vdW heterostructure.Interestingly,a near-zero Poisson’s ratio ν_(zx)is found in BP/SnSe heterostructure.In addition,compared with the parent materials BP and SnSe with strong in-plane anisotropic mechanical properties,the BP/SnSe heterostructure shows strongly suppressed anisotropy.The results show that the vdW heterostructure has quite different mechanical properties compared with the parent materials,and provides new opportunities for the mechanical applications of the heterostructures.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.U2004165,U22A20138,and 11974016)the Natural Science Foundation of Henan Province,China(No.202300410376)+1 种基金Henan Provincial Key Science and Technology Research Projects(No.212102210131)the Open Fund of National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials(No.HKDNM2021012).
文摘Two-dimensional(2D)layered materials have been considered promising candidates for next-generation optoelectronics.However,the performance of 2D photodetectors still has much room for improvement due to weak light absorption of planar 2D materials and lack of high-quality heterojunction preparation technology.Notably,2D materials integrating with mature bulk semiconductors are a promising pathway to overcome this limitation and promote the practical application on optoelectronics.In this work,we present the patterned assembly of MoSe_(2)/pyramid Si mixed-dimensional van der Waals(vdW)heterojunction arrays for broadband photodetection and imaging.Benefited from the light trapping effect induced enhanced optical absorption and high-quality vdW heterojunction,the photodetector demonstrates a wide spectral response range from 265 to 1550 nm,large responsivity up to 0.67 A·W^(-1),high specific detectivity of 1.84×10^(13)Jones,and ultrafast response time of 0.34/5.6μs at 0 V.Moreover,the photodetector array exhibits outstanding broadband image sensing capability.This study offers a novel development route for high-performance and broadband photodetector array by MoSe_(2)/pyramid Si mixed-dimensional heterojunction.
基金the National Natural Science Foundation of China(Grant Nos.51978324,51720105001,and 51962023)the Natural Science Foundation of Jiangxi Province(Grant Nos.20213BCJL22053,20192ACBL20043,and 20212BAB204045)+1 种基金the Department of Education Fund of Jiangxi Province(Grant No.GJJ210913)Graduate Innovation Fund(Grant No.YC2021-011)。
文摘The design of van der Waals heterojunctions with S-scheme charge transfer pathway is expected to be an effective strategy for improvement of photocatalytic performance.Herein,two-dimensional(2D)phosphorus-doped g-C_(3)N_(4)/Bi_(5)O_(7)Ivan der Waals heterojunctions with reduced graphene oxide as electron bridge(PCN/RGO/Bi_(5O)_(7)I)were successfully synthesized via hydrothermal method.The van der Waals interaction endowed 2D PCN/RGO/Bi_(5O)_(7)I with intimate contact interface,lattice match,tunable band structure,and internal electric field,which efficiently promoted interfacial charge separation and enhanced redox ability of photogenerated charge carriers.As a result,the S-scheme PCN/RGO/Bi_5O_7I van der Waals heterojunctions exhibited superior photocatalytic performance in ciprofloxacin degradation and real pharmaceutical wastewater treatment.The optimized 12%PCN/RGO/Bi_5O_7I displayed the highest photocatalytic activity with 92%removal of ciprofloxacin.Importantly,the COD removal efficiency and extent of mineralization of real pharmaceutical wastewater reached 66.9%and 59.8%,respectively,and the biodegradability of pharmaceutical wastewater was significantly improved.The photocatalytic mechanism of the S-scheme PCN/RGO/Bi_(5)O_(7)I van der Waals heterojunctions based on the analysis of reactive species,work function,and internal electric field was presented.This study provides fresh insights into plausible design of S-scheme van der Waals heterojunction to enhance photocatalytic redox ability.
基金supported by the National Key Research and Development Program of China(No.2018YFB2200103)the National Natural Science Foundation of China(No.62074134).
文摘Mixed-dimensional van der Waals(vdW)heterostructures based on two-dimensional transition metal dichalcogenides and threedimensional semiconductors have led to a new era in next-generation optoelectronics due to the high-quality interfaces and energy band complementation,especially in broadband photodetectors which can be used for all-weather navigation,object identification,etc.However,the reported photodetectors conventionally operated in photodiode mode with low responsivity and a narrow response spectrum.In this study,we report a p-WSe_(2)/n-Ge vdW heterojunction phototransistor with a Schottky barrier collector on n-Ge for broadband photodetection.Large hole/electron injection ratio from p-WSe_(2)/n-Ge heterojunction under forward bias due to their large bandgap offset renders the high photocurrent gain,while the Ge Schottky barrier limits the dark current.The responsivities of the phototransistor at 1.0 V emitter-collector bias are 55,95,and 120 A·W−1 at 405,1,310,and 1,550 nm,respectively,which is superior to that of the corresponding p-WSe_(2)/n-Ge photodiodes.The phototransistor shows a high photocurrent gain of 80,a specific detectivity of 1011 Jones,as well as a fast response time of 290μs at 1,550 nm.The results suggest that the novel phototransistor being implemented with complementary metal-oxide-semiconductor processing is an ideal strategy for high-performance broadband photodetection.
