Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO_(2). We combined N-doped graphene quantum dots (N-GQDs), morphology r...Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO_(2). We combined N-doped graphene quantum dots (N-GQDs), morphology regulation, and heterojunction construction strategies to synthesize N-GQD/N-doped TiO_(2)/P-doped porous hollow g-C_(3)N_(4) nanotube (PCN) composite photocatalysts (denoted as G-TPCN). The optimal sample (G-TPCN doped with 0.1wt% N-GQD, denoted as 0.1% G-TPCN) exhibits significantly enhanced photoabsorption, which is attributed to the change in bandgap caused by elemental doping (P and N), the improved light-harvesting resulting from the tube structure, and the upconversion effect of N-GQDs. In addition, the internal charge separation and transfer capability of0.1% G-TPCN are dramatically boosted, and its carrier concentration is 3.7, 2.3, and 1.9 times that of N-TiO_(2), PCN, and N-TiO_(2)/PCN(TPCN-1), respectively. This phenomenon is attributed to the formation of Z-scheme heterojunction between N-TiO_(2) and PCNs, the excellent electron conduction ability of N-GQDs, and the short transfer distance caused by the porous nanotube structure. Compared with those of N-TiO_(2), PCNs, and TPCN-1, the H2 production activity of 0.1%G-TPCN under visible light is enhanced by 12.4, 2.3, and 1.4times, respectively, and its ciprofloxacin (CIP) degradation rate is increased by 7.9, 5.7, and 2.9 times, respectively. The optimized performance benefits from excellent photoresponsiveness and improved carrier separation and migration efficiencies. Finally, the photocatalytic mechanism of 0.1% G-TPCN and five possible degradation pathways of CIP are proposed. This study clarifies the mechanism of multiple modification strategies to synergistically improve the photocatalytic performance of 0.1% G-TPCN and provides a potential strategy for rationally designing novel photocatalysts for environmental remediation and solar energy conversion.展开更多
Based on the density functional calculations, the structural and electronic properties of the WS2/graphene heterojunction under different strains are investigated. The calculated results show that unlike the free mono...Based on the density functional calculations, the structural and electronic properties of the WS2/graphene heterojunction under different strains are investigated. The calculated results show that unlike the free mono-layer WS2, the monolayer WS2 in the equilibrium WS2/graphene heterojunctionis characterized by indirect band gap due to the weak van der Waals interaction. The height of the schottky barrier for the WS2/graphene heterojunction is 0.13 eV, which is lower than the conventional metal/MoS2 contact. Moreover, the band properties and height of schottky barrier for WS2/graphene heterojunction can be tuned by strain. It is found that the height of the schottky barrier can be tuned to be near zero under an in-plane compressive strain, and the band gap of the WS2 in the heterojunction is turned into a direct band gap from the indirect band gap with the increasing schottky barrier height under an in-plane tensile strain. Our calculation results may provide a potential guidance for designing and fabricating the WS2-based field effect transistors.展开更多
Graphene monolayer has been extensively applied as a transparency electrode material in photoelectronic devices due to its high transmittance,high carrier mobility,and ultrafast carrier dynamics.In this study,a high-p...Graphene monolayer has been extensively applied as a transparency electrode material in photoelectronic devices due to its high transmittance,high carrier mobility,and ultrafast carrier dynamics.In this study,a high-performance self-powered photodetector,which is made of a SnO_(2)microwire,p-type GaN film,and monolayer graphene transparent electrode,was proposed and fabricated.The detector is sensitive to ultraviolet light signals and illustrates pronounced detection performances,including a peak respon-sivity∼223.7 mA W^(-1),a detectivity∼6.9×10^(12)Jones,fast response speed(rising/decaying times∼18/580μs),and excellent external quantum efficiency∼77%at 360 nm light illumination without exter-nal power supply.Compared with the pristine SnO_(2)/GaN photodetector using ITO electrode,the device performances of responsivity and detectivity are significantly increased over 6×10^(3)%and 3×10^(3)%,respectively.The performance-enhanced characteristics are mainly attributed to the high-quality het-erointerface of n-SnO_(2)/p-GaN,the highly conductive capacity,and the unique transparency of graphene electrodes.Particularly,the built-in potential formed at the SnO_(2)/GaN heterojunction interface could be strengthened by the Schottky potential barrier derived from the graphene electrode and SnO_(2)wire,en-hancing the carrier collection efficiency through graphene as a charge collection medium.This work is of great importance and significance to developing excellent-performance ultraviolet photodetectors for photovoltaic and optoelectronic applications in a self-powered operation manner.展开更多
Bi_(2)O_(2)CO_(3)(BOC)/Bi_(4)O_5Br_(2)(BOB)/reduced graphene oxide(rGO)Z-scheme heterojunction with promising photocatalytic properties was synthesized via a facile one-pot room-temperature method.Ultra-thin nanosheet...Bi_(2)O_(2)CO_(3)(BOC)/Bi_(4)O_5Br_(2)(BOB)/reduced graphene oxide(rGO)Z-scheme heterojunction with promising photocatalytic properties was synthesized via a facile one-pot room-temperature method.Ultra-thin nanosheets of BOC and BOB were grown in situ on r GO.The formed 2D/2D direct Z-scheme heterojunction of BOC/BOB with oxygen vacancies(OVs)effectively leads to lower negative electron reduction potential of BOB as well as higher positive hole oxidation potential of BOC,showing improved reduction/oxidation ability.Particularly,rGO is an acceptor of the electrons from the conduction band of BOC.Its dual roles significantly improve the transfer performance of photo-induced charge carriers and accelerate their separation.With layered nanosheet structure,rich OVs,high specific surface area,and increased utilization efficiency of visible light,the multiple synergistic effects of BOC/BOB/rGO can achieve effective generation and separation of the electron-holes,thereby generating more·O_(2)^(-)and h^(+).The photocatalytic reduction efficiency of CO_(2)to CO(12.91μmol/(g·hr))is three times higher than that of BOC(4.18μmol/(g·hr)).Moreover,it also achieved almost 100%removal of Rhodamine B and cyanobacterial cells within 2 hours.展开更多
Understanding the fundamental charge carrier dynamics is of great significance for photodetectors with both high speed and high responsivity.Devices based on two-dimensional(2D)transition metal dichalcogenides can exh...Understanding the fundamental charge carrier dynamics is of great significance for photodetectors with both high speed and high responsivity.Devices based on two-dimensional(2D)transition metal dichalcogenides can exhibit picosecond photoresponse speed.However,2D materials naturally have low absorption,and when increasing thickness to gain higher responsivity,the response time usually slows to nanoseconds,limiting their photodetection performance.Here,by taking time-resolved photocurrent measurements,we demonstrated that graphene/MoTe_(2) van der Waals heterojunctions realize a fast 10 ps photoresponse time owing to the reduced average photocurrent drift time in the heterojunction,which is fundamentally distinct from traditional Dirac semimetal photodetectors such as graphene or Cd_(3)As_(2) and implies a photodetection bandwidth as wide as 100 GHz.Furthermore,we found that an additional charge carrier transport channel provided by graphene can ef-fectively decrease the photocurrent recombination loss to the entire device,preserving a high responsivity in the near-infrared region.Our study provides a deeper understanding of the ultrafast electrical response in van der Waals heterojunctions and offers a promising approach for the realization of photodetectors with both high responsivity and ultrafast electrical response.展开更多
The formation of heterojunction within solid-state devices enables them with eventually high performances,but provides a challenge for material synthesis and device fabrication because strict conditions such as lattic...The formation of heterojunction within solid-state devices enables them with eventually high performances,but provides a challenge for material synthesis and device fabrication because strict conditions such as lattice match are needed.Herein,we show a facile method to fabricate a van der Waals(vdW)heterojunction between two-dimensional(2D)bismuth oxyselenide(Bi2O2Se)and graphene,during which the graphene is directly transferred to the Bi2O2Se and served as a lowcontract-resistant electrode with small work function mismatch(~50 meV).As an optoelectronic device,the Bi2O2Se/graphene vdW heterojunction allows for the efficient sensing toward 1200-nm incident laser.Regarding the application of fieldeffect transistors(FETs),the short-channel(50 nm)sample can be synthesized by utilizing these two 2D materials(ie,channel:Bi2O2Se;drain/source terminal:graphene)and the n-type characteristic can be observed with the accordant field modulation.It is confirmed that we show a simple way to prepare the vdW heterojunction which is aiming to the high-performance applications among optoelectronics and FETs.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
One-dimensional nanostructures(1D)with short ion diffusion distance and fast ion transport path are excellent for lithium-ion batteries(LIBs). However, the nature of layered transition metal dichalcogenides makes it d...One-dimensional nanostructures(1D)with short ion diffusion distance and fast ion transport path are excellent for lithium-ion batteries(LIBs). However, the nature of layered transition metal dichalcogenides makes it difficult to form 1D nanohybrids. Here, the MoTe_(2) nanorods with an average diameter of 100-200 nm and length of 1-3 μm encapsulated by reduced graphene oxide(MoTe_(2)/rGO) have been fabricated via in-situ reaction of GO coated Mo_3O_(10)(C_(2)H_(10)N_(2)) nanowires with Te under Ar/H_(2) atmosphere. When applied as anode of LIBs, the Mo Te_(2)/r GO delivers a high reversible capacity(637 m A h g^(-1) after 100 cycles at 0.2 A g^(-1)), good rate capability(374 m A h g^(-1) at 2 A g^(-1)) and excellent stability(360 m A h g^(-1) after 200 cycles at 0.5 A g^(-1)), which surpasses bare Mo Te2 nanorods and bulk Mo Te2 crystallite. Furthermore, a lithium-ion full cell constructed by coupling Mo Te2/r GO anode and LiCoO_(2) cathode shows a capacity of 105 m A h g^(-1) at 0.1 C. The enhanced performance mainly benefits from the advantages of 1D nanostructure, and meanwhile the r GO thin layers are able to improve the conductivity and maintain the structural stability. This work provides a simple pathway for the synthesis of 1D TMDs nanostructures for energy storage and conversion.展开更多
A high-performance heterojunction photodetector is formed by combining an n-type Si substrate with p-type monolayer WSe2 obtained using physical vapor deposition. The high quality of the WSe2/Si heterojunction is demo...A high-performance heterojunction photodetector is formed by combining an n-type Si substrate with p-type monolayer WSe2 obtained using physical vapor deposition. The high quality of the WSe2/Si heterojunction is demonstrated by the suppressed dark current of I nA and the extremely high rectification ratio of 107. Under illumination, the heterojunction exhibits a wide photoresponse range from ultraviolet to near-infrared radiation. The introduction of graphene quantum dots （GQDs） greatly elevates the photodetective capabilities of the heterojunction with strong light absorption and long carrier lifetimes. The GQDs/WSe2/Si heterojunction exhibits a high responsivity of -707 mA·W^-1, short response time of 0.2 ms, and good specific detectivity of -4.51×10^9 Jones. These properties suggest that the GQDs/WSe2/Si heterojunction holds great potential for application in future high- performance photodetectors.展开更多
Most resistance-type humidity sensors exhibit negative humidity sensitivity,i.e.,their resistance decreases with a corresponding increase in humidity.This is primarily attributed to the dominant role of ionic conducti...Most resistance-type humidity sensors exhibit negative humidity sensitivity,i.e.,their resistance decreases with a corresponding increase in humidity.This is primarily attributed to the dominant role of ionic conduction in adsorbed water.In this work,a humidity sensor based on a p-type reduced graphene oxide(p-rGO)with positive humidity sensitivity is proposed.Moreover,its positive humidity sensing response is further enhanced by n-type WS_(2) nanoparticles modification.The results show that both rGO and r GO/WS_(2) humidity sensors have good linear response in the relative humidity(RH)range of0%-91.5%.The sensitivity of the rGO/WS_(2) humidity sensor is 1.87 times that of rGO humidity sensor,which is mainly attributed to p-n heterojunction between rGO and WS_(2).Besides,the r GO/WS_(2) humidity sensor has small humidity hysteresis(-3%RH)and good repeatability.This work demonstrates a humidity sensor based on rGO/WS_(2) composite film and provides a facile route for fabricating humidity sensor with positive humidity sensing properties.展开更多
Two-dimensional(2D)transition metal dichalcogenides have been extensively studied due to their fascinating physical properties for constructing high-performance photodetectors.However,their relatively low responsiviti...Two-dimensional(2D)transition metal dichalcogenides have been extensively studied due to their fascinating physical properties for constructing high-performance photodetectors.However,their relatively low responsivities,current on/off ratios and response speeds have hindered their widespread application.Herein,we fabricated a high-performance photodetector based on few-layer MoTe_(2) and CdS_(0.42)Se_(0.58) flake heterojunctions.The photodetector exhibited a high responsivity of 7221 A/W,a large current on/off ratio of 1.73×10^(4),a fast response speed of 90/120μs,external quantum efficiency(EQE)reaching up to 1.52×10^(6)%and detectivity(D*)reaching up to 1.67×10^(15) Jones.The excellent performance of the heterojunction photodetector was analyzed by a photocurrent mapping test and first-principle calculations.Notably,the visible light imaging function was successfully attained on the MoTe_(2)/CdS_(0.42)Se_(0.58) photodetectors,indicating that the device had practical imaging application prospects.Our findings provide a reference for the design of ultrahighperformance MoTe_(2)-based photodetectors.展开更多
Two-dimensional(2D)materials have attracted great attention in optoelectronics because of their unique structure,optical and electrical properties.Designing high-performance photodetectors and implementing their appli...Two-dimensional(2D)materials have attracted great attention in optoelectronics because of their unique structure,optical and electrical properties.Designing high-performance photodetectors and implementing their applications are eager to promote the development of 2D materials.Position-sensitive detector(PSD)is an optical inspection device for the precise measurements of position,distance,angle,and other relevant physical variables.It is a widely used component in the fields of tracking,aerospace,nanorobotics,and so forth.Essentially,PSD is also a photodetector based on the lateral photovoltaic effect(LPE).This article reviews recent progress in high-performance PSD based on 2D materials.The high-sensitive photodetectors and LPE involved in 2D photodetectors are firstly discussed.Then,we introduce the research progress of PSD based on 2D materials and analyze the carrier dynamics in different device structures.Finally,we summarize the functionalities and applications of PSD based on 2D materials,and highlight the challenges and opportunities in this research area.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.U2002212,52102058,52204414,52204413,and 52204412)the National Key R&D Program of China (Nos.2021YFC1910504,2019YFC1907101,2019YFC1907103,and 2017YFB0702304)+7 种基金the Key R&D Program of Ningxia Hui Autonomous Region,China (Nos.2021BEG01003 and2020BCE01001)the Xijiang Innovation and Entrepreneurship Team,China (No.2017A0109004)the Macao Young Scholars Program (No.AM2022024),Chinathe Beijing Natural Science Foundation (Nos.L212020 and 2214073),Chinathe Guangdong Basic and Applied Basic Research Foundation,China (Nos.2021A1515110998 and 2020A1515110408)the China Postdoctoral Science Foundation (No.2022M710349)the Fundamental Research Funds for the Central Universities,China (Nos.FRF-BD-20-24A,FRF-TP-20-031A1,FRF-IC-19-017Z,and 06500141)the Integration of Green Key Process Systems MIIT and Scientific and Technological Innovation Foundation of Foshan,China(Nos.BK22BE001 and BK21BE002)。
文摘Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO_(2). We combined N-doped graphene quantum dots (N-GQDs), morphology regulation, and heterojunction construction strategies to synthesize N-GQD/N-doped TiO_(2)/P-doped porous hollow g-C_(3)N_(4) nanotube (PCN) composite photocatalysts (denoted as G-TPCN). The optimal sample (G-TPCN doped with 0.1wt% N-GQD, denoted as 0.1% G-TPCN) exhibits significantly enhanced photoabsorption, which is attributed to the change in bandgap caused by elemental doping (P and N), the improved light-harvesting resulting from the tube structure, and the upconversion effect of N-GQDs. In addition, the internal charge separation and transfer capability of0.1% G-TPCN are dramatically boosted, and its carrier concentration is 3.7, 2.3, and 1.9 times that of N-TiO_(2), PCN, and N-TiO_(2)/PCN(TPCN-1), respectively. This phenomenon is attributed to the formation of Z-scheme heterojunction between N-TiO_(2) and PCNs, the excellent electron conduction ability of N-GQDs, and the short transfer distance caused by the porous nanotube structure. Compared with those of N-TiO_(2), PCNs, and TPCN-1, the H2 production activity of 0.1%G-TPCN under visible light is enhanced by 12.4, 2.3, and 1.4times, respectively, and its ciprofloxacin (CIP) degradation rate is increased by 7.9, 5.7, and 2.9 times, respectively. The optimized performance benefits from excellent photoresponsiveness and improved carrier separation and migration efficiencies. Finally, the photocatalytic mechanism of 0.1% G-TPCN and five possible degradation pathways of CIP are proposed. This study clarifies the mechanism of multiple modification strategies to synergistically improve the photocatalytic performance of 0.1% G-TPCN and provides a potential strategy for rationally designing novel photocatalysts for environmental remediation and solar energy conversion.
基金Project supported by the National Natural Science Foundation of China(Grant No.11202178)
文摘Based on the density functional calculations, the structural and electronic properties of the WS2/graphene heterojunction under different strains are investigated. The calculated results show that unlike the free mono-layer WS2, the monolayer WS2 in the equilibrium WS2/graphene heterojunctionis characterized by indirect band gap due to the weak van der Waals interaction. The height of the schottky barrier for the WS2/graphene heterojunction is 0.13 eV, which is lower than the conventional metal/MoS2 contact. Moreover, the band properties and height of schottky barrier for WS2/graphene heterojunction can be tuned by strain. It is found that the height of the schottky barrier can be tuned to be near zero under an in-plane compressive strain, and the band gap of the WS2 in the heterojunction is turned into a direct band gap from the indirect band gap with the increasing schottky barrier height under an in-plane tensile strain. Our calculation results may provide a potential guidance for designing and fabricating the WS2-based field effect transistors.
基金This work was financially supported by the National Natural Science Foundation of China(NSFC)(Nos.11974182 and 11874220)Fundamental Research Funds for the Central Universities(No.NC2022008)Funding for Outstanding Doctoral Dissertation in NUAA(No.BCXJ22-14).
文摘Graphene monolayer has been extensively applied as a transparency electrode material in photoelectronic devices due to its high transmittance,high carrier mobility,and ultrafast carrier dynamics.In this study,a high-performance self-powered photodetector,which is made of a SnO_(2)microwire,p-type GaN film,and monolayer graphene transparent electrode,was proposed and fabricated.The detector is sensitive to ultraviolet light signals and illustrates pronounced detection performances,including a peak respon-sivity∼223.7 mA W^(-1),a detectivity∼6.9×10^(12)Jones,fast response speed(rising/decaying times∼18/580μs),and excellent external quantum efficiency∼77%at 360 nm light illumination without exter-nal power supply.Compared with the pristine SnO_(2)/GaN photodetector using ITO electrode,the device performances of responsivity and detectivity are significantly increased over 6×10^(3)%and 3×10^(3)%,respectively.The performance-enhanced characteristics are mainly attributed to the high-quality het-erointerface of n-SnO_(2)/p-GaN,the highly conductive capacity,and the unique transparency of graphene electrodes.Particularly,the built-in potential formed at the SnO_(2)/GaN heterojunction interface could be strengthened by the Schottky potential barrier derived from the graphene electrode and SnO_(2)wire,en-hancing the carrier collection efficiency through graphene as a charge collection medium.This work is of great importance and significance to developing excellent-performance ultraviolet photodetectors for photovoltaic and optoelectronic applications in a self-powered operation manner.
基金supported by the National Natural Science Foundation of China(Nos.51602281 and 52100014)the Natural Science Foundation of Jiangsu Province(No.BK20180938)the Yangzhou University High-end Talent Support Program and the“Qinglan Project”of Jiangsu Universities。
文摘Bi_(2)O_(2)CO_(3)(BOC)/Bi_(4)O_5Br_(2)(BOB)/reduced graphene oxide(rGO)Z-scheme heterojunction with promising photocatalytic properties was synthesized via a facile one-pot room-temperature method.Ultra-thin nanosheets of BOC and BOB were grown in situ on r GO.The formed 2D/2D direct Z-scheme heterojunction of BOC/BOB with oxygen vacancies(OVs)effectively leads to lower negative electron reduction potential of BOB as well as higher positive hole oxidation potential of BOC,showing improved reduction/oxidation ability.Particularly,rGO is an acceptor of the electrons from the conduction band of BOC.Its dual roles significantly improve the transfer performance of photo-induced charge carriers and accelerate their separation.With layered nanosheet structure,rich OVs,high specific surface area,and increased utilization efficiency of visible light,the multiple synergistic effects of BOC/BOB/rGO can achieve effective generation and separation of the electron-holes,thereby generating more·O_(2)^(-)and h^(+).The photocatalytic reduction efficiency of CO_(2)to CO(12.91μmol/(g·hr))is three times higher than that of BOC(4.18μmol/(g·hr)).Moreover,it also achieved almost 100%removal of Rhodamine B and cyanobacterial cells within 2 hours.
基金This work was supported by the National Natural Science Foundation of China(Grants No.52022029,91850116,51772084,and U19A2090)the Sino-German Center for Research Promotion(Grant No.GZ1390)the Hunan Provincial Natural Science Foundation of China(Grants No.2018RS3051 and 2019XK2001)。
文摘Understanding the fundamental charge carrier dynamics is of great significance for photodetectors with both high speed and high responsivity.Devices based on two-dimensional(2D)transition metal dichalcogenides can exhibit picosecond photoresponse speed.However,2D materials naturally have low absorption,and when increasing thickness to gain higher responsivity,the response time usually slows to nanoseconds,limiting their photodetection performance.Here,by taking time-resolved photocurrent measurements,we demonstrated that graphene/MoTe_(2) van der Waals heterojunctions realize a fast 10 ps photoresponse time owing to the reduced average photocurrent drift time in the heterojunction,which is fundamentally distinct from traditional Dirac semimetal photodetectors such as graphene or Cd_(3)As_(2) and implies a photodetection bandwidth as wide as 100 GHz.Furthermore,we found that an additional charge carrier transport channel provided by graphene can ef-fectively decrease the photocurrent recombination loss to the entire device,preserving a high responsivity in the near-infrared region.Our study provides a deeper understanding of the ultrafast electrical response in van der Waals heterojunctions and offers a promising approach for the realization of photodetectors with both high responsivity and ultrafast electrical response.
基金support from the National Basic Research Program of China(No.2016YFA0200101)the National Natural Science Foundation of China(Nos.21733001 and 21525310)Boya Postdoctoral Fellowship.
文摘The formation of heterojunction within solid-state devices enables them with eventually high performances,but provides a challenge for material synthesis and device fabrication because strict conditions such as lattice match are needed.Herein,we show a facile method to fabricate a van der Waals(vdW)heterojunction between two-dimensional(2D)bismuth oxyselenide(Bi2O2Se)and graphene,during which the graphene is directly transferred to the Bi2O2Se and served as a lowcontract-resistant electrode with small work function mismatch(~50 meV).As an optoelectronic device,the Bi2O2Se/graphene vdW heterojunction allows for the efficient sensing toward 1200-nm incident laser.Regarding the application of fieldeffect transistors(FETs),the short-channel(50 nm)sample can be synthesized by utilizing these two 2D materials(ie,channel:Bi2O2Se;drain/source terminal:graphene)and the n-type characteristic can be observed with the accordant field modulation.It is confirmed that we show a simple way to prepare the vdW heterojunction which is aiming to the high-performance applications among optoelectronics and FETs.
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 Natural Science Foundation of China(11904108)the“Pearl River Talent Recruitment Program”(2019ZT08X639)Guangdong Basic and Applied Basic Research Foundation(2024A1515030107).
基金supported by the National Natural Science Foundation of China (21771137)。
文摘One-dimensional nanostructures(1D)with short ion diffusion distance and fast ion transport path are excellent for lithium-ion batteries(LIBs). However, the nature of layered transition metal dichalcogenides makes it difficult to form 1D nanohybrids. Here, the MoTe_(2) nanorods with an average diameter of 100-200 nm and length of 1-3 μm encapsulated by reduced graphene oxide(MoTe_(2)/rGO) have been fabricated via in-situ reaction of GO coated Mo_3O_(10)(C_(2)H_(10)N_(2)) nanowires with Te under Ar/H_(2) atmosphere. When applied as anode of LIBs, the Mo Te_(2)/r GO delivers a high reversible capacity(637 m A h g^(-1) after 100 cycles at 0.2 A g^(-1)), good rate capability(374 m A h g^(-1) at 2 A g^(-1)) and excellent stability(360 m A h g^(-1) after 200 cycles at 0.5 A g^(-1)), which surpasses bare Mo Te2 nanorods and bulk Mo Te2 crystallite. Furthermore, a lithium-ion full cell constructed by coupling Mo Te2/r GO anode and LiCoO_(2) cathode shows a capacity of 105 m A h g^(-1) at 0.1 C. The enhanced performance mainly benefits from the advantages of 1D nanostructure, and meanwhile the r GO thin layers are able to improve the conductivity and maintain the structural stability. This work provides a simple pathway for the synthesis of 1D TMDs nanostructures for energy storage and conversion.
文摘A high-performance heterojunction photodetector is formed by combining an n-type Si substrate with p-type monolayer WSe2 obtained using physical vapor deposition. The high quality of the WSe2/Si heterojunction is demonstrated by the suppressed dark current of I nA and the extremely high rectification ratio of 107. Under illumination, the heterojunction exhibits a wide photoresponse range from ultraviolet to near-infrared radiation. The introduction of graphene quantum dots （GQDs） greatly elevates the photodetective capabilities of the heterojunction with strong light absorption and long carrier lifetimes. The GQDs/WSe2/Si heterojunction exhibits a high responsivity of -707 mA·W^-1, short response time of 0.2 ms, and good specific detectivity of -4.51×10^9 Jones. These properties suggest that the GQDs/WSe2/Si heterojunction holds great potential for application in future high- performance photodetectors.
基金the National Science Funds for Excellent Young Scholars of China(No.61822106)the National Science Funds for Creative Research Groups of China(No.61421002)the National Natural Science Foundation of China(No.61671115)。
文摘Most resistance-type humidity sensors exhibit negative humidity sensitivity,i.e.,their resistance decreases with a corresponding increase in humidity.This is primarily attributed to the dominant role of ionic conduction in adsorbed water.In this work,a humidity sensor based on a p-type reduced graphene oxide(p-rGO)with positive humidity sensitivity is proposed.Moreover,its positive humidity sensing response is further enhanced by n-type WS_(2) nanoparticles modification.The results show that both rGO and r GO/WS_(2) humidity sensors have good linear response in the relative humidity(RH)range of0%-91.5%.The sensitivity of the rGO/WS_(2) humidity sensor is 1.87 times that of rGO humidity sensor,which is mainly attributed to p-n heterojunction between rGO and WS_(2).Besides,the r GO/WS_(2) humidity sensor has small humidity hysteresis(-3%RH)and good repeatability.This work demonstrates a humidity sensor based on rGO/WS_(2) composite film and provides a facile route for fabricating humidity sensor with positive humidity sensing properties.
基金This work was supported by the National Natural Science Foundation of China(Nos.11864046 and 11764046)the Basic Research Program of Yunnan Province(Nos.202001AT070064 and 202101AT070124)+1 种基金the Spring City Plan(Highlevel Talent Promotion and Training Project of Kunming)(No.2022SCP005)Yunnan Expert Workstation(No.202205AF150008).
文摘Two-dimensional(2D)transition metal dichalcogenides have been extensively studied due to their fascinating physical properties for constructing high-performance photodetectors.However,their relatively low responsivities,current on/off ratios and response speeds have hindered their widespread application.Herein,we fabricated a high-performance photodetector based on few-layer MoTe_(2) and CdS_(0.42)Se_(0.58) flake heterojunctions.The photodetector exhibited a high responsivity of 7221 A/W,a large current on/off ratio of 1.73×10^(4),a fast response speed of 90/120μs,external quantum efficiency(EQE)reaching up to 1.52×10^(6)%and detectivity(D*)reaching up to 1.67×10^(15) Jones.The excellent performance of the heterojunction photodetector was analyzed by a photocurrent mapping test and first-principle calculations.Notably,the visible light imaging function was successfully attained on the MoTe_(2)/CdS_(0.42)Se_(0.58) photodetectors,indicating that the device had practical imaging application prospects.Our findings provide a reference for the design of ultrahighperformance MoTe_(2)-based photodetectors.
基金the National Natural Science Foundation of China(Nos.61927808,61774034,and 11704068)the National Key Research and Development Program of China(No.2017YFA0205700)China Postdoctoral Science Foundation(No.2018M632197).
文摘Two-dimensional(2D)materials have attracted great attention in optoelectronics because of their unique structure,optical and electrical properties.Designing high-performance photodetectors and implementing their applications are eager to promote the development of 2D materials.Position-sensitive detector(PSD)is an optical inspection device for the precise measurements of position,distance,angle,and other relevant physical variables.It is a widely used component in the fields of tracking,aerospace,nanorobotics,and so forth.Essentially,PSD is also a photodetector based on the lateral photovoltaic effect(LPE).This article reviews recent progress in high-performance PSD based on 2D materials.The high-sensitive photodetectors and LPE involved in 2D photodetectors are firstly discussed.Then,we introduce the research progress of PSD based on 2D materials and analyze the carrier dynamics in different device structures.Finally,we summarize the functionalities and applications of PSD based on 2D materials,and highlight the challenges and opportunities in this research area.
