Paper-based devices have attracted extensive attention due to the growing demand for disposable flexible electronics.Herein,we integrate semiconducting devices on cellulose paper substrate through a simple abrasion te...Paper-based devices have attracted extensive attention due to the growing demand for disposable flexible electronics.Herein,we integrate semiconducting devices on cellulose paper substrate through a simple abrasion technique that yields high-performance photodetectors.A solvent-free WS_(2) film deposited on paper favors an effective electron-hole separation and hampers recombination.The as-prepared paper-based WS2 photodetectors exhibit a sensitive photoresponse over a wide spectral range spanning from ultraviolet(365 nm)to near-infrared(940 nm).Their responsivity value reaches up to~270 mA W^(−1) at 35 V under a power density of 35 mW cm^(−2).A high performance photodetector was achieved by controlling the environmental exposure as the ambient oxygen molecules were found to decrease the photoresponse and stability of the WS_(2) photodetector.Furthermore,we have built a spectrometer using such a paperbased WS_(2) device as the photodetecting component to illustrate its potential application.The present work could promote the development of cost-effective disposable photodetection devices.展开更多
Strain engineering has arisen as a powerful technique to tune the electronic and optical properties of twod imensional semiconductors like molybdenum disulfide(MoS_(2)).Although several theoretical works predicted tha...Strain engineering has arisen as a powerful technique to tune the electronic and optical properties of twod imensional semiconductors like molybdenum disulfide(MoS_(2)).Although several theoretical works predicted that biaxial strain would be more effective than uniaxial strain to tune the band structure of MoS_(2),a direct experimental verification is still missing in the literature.Here we implemented a simple experimental setup that allows to apply biaxial strain through the bending of a cruciform polymer substrate.We used the setup to study the effect of biaxial strain on the differential reflectance spectra of 12 single-layer MoS_(2)flakes finding a redshift of the excitonic features at a rate between-40 meV/%and-110 meV/%of biaxial tension.We also directly compare the effect of biaxi al and uniaxial strain on the same single-layer MoS_(2)finding that the biaxial strain gauge factor is 2.3 times larger than the uniaxial strain one.展开更多
We present a method to fabricate handcrafted thermoelectric devices on standard office paper substrates.The devices are based on thin films of WS_(2),Te,and BP(P-type semiconductors)and TiS_(3)and TiS_(2)(N-type semic...We present a method to fabricate handcrafted thermoelectric devices on standard office paper substrates.The devices are based on thin films of WS_(2),Te,and BP(P-type semiconductors)and TiS_(3)and TiS_(2)(N-type semiconductors),deposited by simply rubbing powder of these materials against paper.The thermoelectric properties of these semiconducting films revealed maximum Seebeck coefficients of(+1.32±0.27)mV K^(-1)and(-0.82±0.15)mV K^(-1)for WS_(2)and TiS_(3),respectively.Additionally,Peltier elements were fabricated by interconnecting the P-and N-type films with graphite electrodes.A thermopower value up to 6.11 mV K^(-1)was obtained when the Peltier element were constructed with three junctions.The findings of this work show proof-of-concept devices to illustrate the potential application of semiconducting van der Waals materials in future thermoelectric power generation as well as temperature sensing for low-cost disposable electronic devices.展开更多
Here,we propose a method to determine the thickness of the most common transition metal dichalcogenides (TMDCs) placed on the surface of transparent stamps,used for the deterministic placement of two-dimensional mater...Here,we propose a method to determine the thickness of the most common transition metal dichalcogenides (TMDCs) placed on the surface of transparent stamps,used for the deterministic placement of two-dimensional materials,by analyzing the red,green and blue channels of transmission-mode optical microscopy images of the samples.In particular,the blue channel transmittance shows a large and monotonic thickness dependence,making it a very convenient probe of the flake thickness.The method proves to be robust given the small flake-to-flake variation and the insensitivity to doping changes of MoS2.We also tested the method for MoSe2,WS2 and WSe2.These results provide a reference guide to identify the number of layers of this family of materials on transparent substrates only using optical microscopy.展开更多
Strain is a powerful tool to modify the optical properties of semiconducting transition metal dichalcogenides like MoS_(2),MoSe_(2),WS_(2) and WSe_(2).In this work we provide a thorough description of the technical de...Strain is a powerful tool to modify the optical properties of semiconducting transition metal dichalcogenides like MoS_(2),MoSe_(2),WS_(2) and WSe_(2).In this work we provide a thorough description of the technical details to perform uniaxial strain measurements on these two-dimensional semiconductors and we provide a straightforward calibration method to determine the amount of applied strain with high accuracy.We then employ reflectance spectroscopy to analyze the strain tunability of the electronic properties of single-,bi-and tri-layer MoS_(2),MoSe_(2),WS_(2) and WSe_(2).Finally,we quantify the flake-to-flake variability by analyzing 15 different single-layer MoS_(2) flakes.展开更多
Two-dimensional materials are attractive for constructing high-performance photonic chip-integrated photodetectors because of their remarkable electronic and optical properties and dangling-bond-free surfaces.However,...Two-dimensional materials are attractive for constructing high-performance photonic chip-integrated photodetectors because of their remarkable electronic and optical properties and dangling-bond-free surfaces.However,the reported chip-integrated two-dimensional material photodetectors were mainly implemented with the configuration of metalsemiconductor-metal,suffering from high dark currents and low responsivities at high operation speed.Here,we report a van der Waals PN heterojunction photodetector,composed of p-type black phosphorous and n-type molybdenum telluride,integrated on a silicon nitride waveguide.The built-in electric field of the PN heterojunction significantly suppresses the dark current and improves the responsivity.Under a bias of 1 V pointing from n-type molybdenum telluride to p-type black phosphorous,the dark current is lower than 7 nA,which is more than two orders of magnitude lower than those reported in other waveguide-integrated black phosphorus photodetectors.An intrinsic responsivity up to 577 mA W^(−1) is obtained.Remarkably,the van der Waals PN heterojunction is tunable by the electrostatic doping to further engineer its rectification and improve the photodetection,enabling an increased responsivity of 709 mA W^(−1).Besides,the heterojunction photodetector exhibits a response bandwidth of~1.0 GHz and a uniform photodetection over a wide spectral range,as experimentally measured from 1500 to 1630 nm.The demonstrated chip-integrated van der Waals PN heterojunction photodetector with low dark current,high responsivity and fast response has great potentials to develop high-performance on-chip photodetectors for various photonic integrated circuits based on silicon,lithium niobate,polymer,etc.展开更多
A well-established strategy to synthesize heterogeneous,metal-organic framework(MOF)catalysts that exhibit nanoconfinement effects,and specific pores with highly-localized catalytic sites,is to use organic linkers con...A well-established strategy to synthesize heterogeneous,metal-organic framework(MOF)catalysts that exhibit nanoconfinement effects,and specific pores with highly-localized catalytic sites,is to use organic linkers containing organocatalytic centers.Here,we report that by combining this linker approach with reticular chemistry,and exploiting three-dimensioanl(3D)MOF-structural data from the Cambridge Structural Database,we have designed four heterogeneous MOF-based catalysts for standard organic transformations.These programmable MOFs are isoreticular versions of pcu IRMOF-16,feu UiO-68 and pillared-pcu SNU-8X,the three most common topologies of MOFs built from the organic linker p.p'-terphenyldicarboxylic acid(tpdc).To synthesize the four squaramide-based MOFs,we designed and synthesized a linker,4,4’-((3,4-dioxocyclobut-1-ene-1,2-diyl)bis(azanedyil))dibenzoic acid(Sq_tpdc),which is identical in directionality and length to tpdc but which contains organocatalytic squaramide centers.Squaramides were chosen because their immobilization into a framework enhances its reactivity and stability while avoiding any self-quenching phenomena.Therefore,the four MOFs share the same organocatalytic squaramide moiety,but confine it within distinct pore environments.We then evaluated these MOFs as heterogeneous H-bonding catalysts in organic transformations:a Friedel-Crafts alkylation and an epoxide ring-opening.Some of them exhibited good performance in both reactions but all showed distinct catalytic profiles that reflect their structural differences.展开更多
We present a low-cost and easy-to-implement technique to fabricate large-area WS_(2) photodetector devices onto transparent and flexible polycarbonate substrates.The method relies on the deposition of large-area(in th...We present a low-cost and easy-to-implement technique to fabricate large-area WS_(2) photodetector devices onto transparent and flexible polycarbonate substrates.The method relies on the deposition of large-area(in the cm scale)thin films(~30 nm thick)of WS_(2) by a recently introduced abrasion-induced method.Interdigitated electrical contacts are then deposited by thermal evaporation through a shadow mask.The photodetectors present well-balanced performances with an good trade-off between responsivity(up to 144 mA/W at a source-drain voltage of 10 V and illumination power of 1μW)and response time(down to~70µs)and a detectivity value of 10^(8) Jones.We found that the devices perform very reversibly upon several illumination and straining cycles and we found a moderate device-to-device variation.展开更多
Single-layer MoS_(2)produced by mechanical exfoliation is usually connected to thicker and multilayer regions.We show a facile laser trimming method to insulate single-layer MoS_(2)regions from thicker ones.We demonst...Single-layer MoS_(2)produced by mechanical exfoliation is usually connected to thicker and multilayer regions.We show a facile laser trimming method to insulate single-layer MoS_(2)regions from thicker ones.We demonstrate,through electrical characterization,that the laser trimming method can be used to pattern single-layer MoS_(2)channels with regular geometry and electrically disconnected from the thicker areas.Scanning photocurrent microscope further confirms that in the as-deposited flake(connected to a multilayer area)most of the photocurrent is being generated in the thicker flake region.After laser trimming,scanning photocurrent microscopy shows how only the single-layer MoS_(2)region contributes to the photocurrent generation.The presented method is a direct-write and lithography-free(no need of resist or wet chemicals)alternative to reactive ion etching process to pattern the flakes that can be easily adopted by many research groups fabricating devices with MoS_(2) and similar twodimensional materials.展开更多
基金Felix Carrascoso (ICMM-CSIC) for support with the metal evaporationfunding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement n°755655,ERC-StG 2017 project2D-TOPSENSE)+5 种基金the Ministry of Science and Innovation (Spain) through the project PID2020-115566RB-I00support from the National Natural Science Foundation of China under grant No.61704129 and No.62011530438the Key Research and Development Program of Shaanxi (Program No.2021KW-02)Fundamental Research Funds for the Central Universities (JB211409)the grant from China Scholarship Council (CSC) under No.201908610178the support from European Union’s Horizon 2020 research and innovation program under the grant agreement 956813 (2Exciting)。
文摘Paper-based devices have attracted extensive attention due to the growing demand for disposable flexible electronics.Herein,we integrate semiconducting devices on cellulose paper substrate through a simple abrasion technique that yields high-performance photodetectors.A solvent-free WS_(2) film deposited on paper favors an effective electron-hole separation and hampers recombination.The as-prepared paper-based WS2 photodetectors exhibit a sensitive photoresponse over a wide spectral range spanning from ultraviolet(365 nm)to near-infrared(940 nm).Their responsivity value reaches up to~270 mA W^(−1) at 35 V under a power density of 35 mW cm^(−2).A high performance photodetector was achieved by controlling the environmental exposure as the ambient oxygen molecules were found to decrease the photoresponse and stability of the WS_(2) photodetector.Furthermore,we have built a spectrometer using such a paperbased WS_(2) device as the photodetecting component to illustrate its potential application.The present work could promote the development of cost-effective disposable photodetection devices.
基金funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement n° 755655, ERC-St G 2017 project 2D-TOPSENSE)the support from the Spanish Ministry of Economy, Industry and Competitiveness through a Juan de la Cierva-formación fellowship 2017 FJCI2017-32919.
文摘Strain engineering has arisen as a powerful technique to tune the electronic and optical properties of twod imensional semiconductors like molybdenum disulfide(MoS_(2)).Although several theoretical works predicted that biaxial strain would be more effective than uniaxial strain to tune the band structure of MoS_(2),a direct experimental verification is still missing in the literature.Here we implemented a simple experimental setup that allows to apply biaxial strain through the bending of a cruciform polymer substrate.We used the setup to study the effect of biaxial strain on the differential reflectance spectra of 12 single-layer MoS_(2)flakes finding a redshift of the excitonic features at a rate between-40 meV/%and-110 meV/%of biaxial tension.We also directly compare the effect of biaxi al and uniaxial strain on the same single-layer MoS_(2)finding that the biaxial strain gauge factor is 2.3 times larger than the uniaxial strain one.
基金funded by the European Research Council(ERC)under the European Union's Horizon 2020 research and innovation program(grant agreement no.755655,ERC-StG 2017 project 2D-TOPSENSE)the Ministry of Science and Innovation(Spain)through the project PID2020-115566RB-I00+7 种基金the Distinguished Scientist Fellowship Program(DSFP)at King Saud University for partial funding of this workfinancial support from the Agencia Estatal de Investigación of Spain(Grants PID2019-106820RB,RTI2018-097180-B-100,and PGC2018-097018-B-I00)the Junta de Castilla y León(Grants SA256P18 and SA121P20),including funding by ERDF/FEDERfinancial support from Universidad Complutense de Madrid and European Commission(MSCA COFUND UNA4CAREER grant.Project number 4129252)financial support from MICINN(Spain)through the program Juan de la Cierva-Incorporaciónthe financial support of the Spanish Ministry of Industry and Competitiveness to the project MAT2017-84496-Rfinancial support from the Ministry of Science and Innovation(Spain)through the project RT2018-099794-B-100financial support from the Ministry de Universities(Spain)(Ph.D.contract FPU19/04224)
文摘We present a method to fabricate handcrafted thermoelectric devices on standard office paper substrates.The devices are based on thin films of WS_(2),Te,and BP(P-type semiconductors)and TiS_(3)and TiS_(2)(N-type semiconductors),deposited by simply rubbing powder of these materials against paper.The thermoelectric properties of these semiconducting films revealed maximum Seebeck coefficients of(+1.32±0.27)mV K^(-1)and(-0.82±0.15)mV K^(-1)for WS_(2)and TiS_(3),respectively.Additionally,Peltier elements were fabricated by interconnecting the P-and N-type films with graphite electrodes.A thermopower value up to 6.11 mV K^(-1)was obtained when the Peltier element were constructed with three junctions.The findings of this work show proof-of-concept devices to illustrate the potential application of semiconducting van der Waals materials in future thermoelectric power generation as well as temperature sensing for low-cost disposable electronic devices.
文摘Here,we propose a method to determine the thickness of the most common transition metal dichalcogenides (TMDCs) placed on the surface of transparent stamps,used for the deterministic placement of two-dimensional materials,by analyzing the red,green and blue channels of transmission-mode optical microscopy images of the samples.In particular,the blue channel transmittance shows a large and monotonic thickness dependence,making it a very convenient probe of the flake thickness.The method proves to be robust given the small flake-to-flake variation and the insensitivity to doping changes of MoS2.We also tested the method for MoSe2,WS2 and WSe2.These results provide a reference guide to identify the number of layers of this family of materials on transparent substrates only using optical microscopy.
基金This project has received funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme(grant agreement no 755655,ERC-StG 2017 project 2D-TOPSENSE)R.F.acknowledges the support from the Spanish Ministry of Economy,Industry and Competitiveness through a Juan de la Cierva-formación fellowship 2017 FJCI-2017-32919.H.L.acknowledges the grant from China Scholarship Council(CSC)under No.201907040070.
文摘Strain is a powerful tool to modify the optical properties of semiconducting transition metal dichalcogenides like MoS_(2),MoSe_(2),WS_(2) and WSe_(2).In this work we provide a thorough description of the technical details to perform uniaxial strain measurements on these two-dimensional semiconductors and we provide a straightforward calibration method to determine the amount of applied strain with high accuracy.We then employ reflectance spectroscopy to analyze the strain tunability of the electronic properties of single-,bi-and tri-layer MoS_(2),MoSe_(2),WS_(2) and WSe_(2).Finally,we quantify the flake-to-flake variability by analyzing 15 different single-layer MoS_(2) flakes.
基金supported by the National Key R&D Program of China(Grant Nos.2018YFA0307200 and 2017YFA0303800)the National Natural Science Foundation of China(Grant Nos.61905198,61775183,11634010,and 61675171)+1 种基金Key Research and Development Program in Shaanxi Province of China(Grant Nos.2017KJXX-12,2018JM1058,and 2018KW-009)the Fundamental Research Funds for the Central Universities(Grant Nos.3102017jc01001,3102018jcc034,and 3102017HQZZ022)。
文摘Two-dimensional materials are attractive for constructing high-performance photonic chip-integrated photodetectors because of their remarkable electronic and optical properties and dangling-bond-free surfaces.However,the reported chip-integrated two-dimensional material photodetectors were mainly implemented with the configuration of metalsemiconductor-metal,suffering from high dark currents and low responsivities at high operation speed.Here,we report a van der Waals PN heterojunction photodetector,composed of p-type black phosphorous and n-type molybdenum telluride,integrated on a silicon nitride waveguide.The built-in electric field of the PN heterojunction significantly suppresses the dark current and improves the responsivity.Under a bias of 1 V pointing from n-type molybdenum telluride to p-type black phosphorous,the dark current is lower than 7 nA,which is more than two orders of magnitude lower than those reported in other waveguide-integrated black phosphorus photodetectors.An intrinsic responsivity up to 577 mA W^(−1) is obtained.Remarkably,the van der Waals PN heterojunction is tunable by the electrostatic doping to further engineer its rectification and improve the photodetection,enabling an increased responsivity of 709 mA W^(−1).Besides,the heterojunction photodetector exhibits a response bandwidth of~1.0 GHz and a uniform photodetection over a wide spectral range,as experimentally measured from 1500 to 1630 nm.The demonstrated chip-integrated van der Waals PN heterojunction photodetector with low dark current,high responsivity and fast response has great potentials to develop high-performance on-chip photodetectors for various photonic integrated circuits based on silicon,lithium niobate,polymer,etc.
基金the Spanish MINECO(projects RTI2018-095622-B-I00,RTI2018-095038-B-I00)the Catalan AGAUR(project 2017 SGR 238)+1 种基金the ERC under the EU FP7(ER C-Co 615954)European Unions Horizon 2020 research and innovation program under grant agreement No.685727,and European Structural Funds(S2018/NMT-4367).It was alsofunded by the CERCA Program/Generalitat de Catalunya.ICN2 is supported by the Severo Ochoa program from the Spanish MINECO(G rant No.SEV-2017-0706).
文摘A well-established strategy to synthesize heterogeneous,metal-organic framework(MOF)catalysts that exhibit nanoconfinement effects,and specific pores with highly-localized catalytic sites,is to use organic linkers containing organocatalytic centers.Here,we report that by combining this linker approach with reticular chemistry,and exploiting three-dimensioanl(3D)MOF-structural data from the Cambridge Structural Database,we have designed four heterogeneous MOF-based catalysts for standard organic transformations.These programmable MOFs are isoreticular versions of pcu IRMOF-16,feu UiO-68 and pillared-pcu SNU-8X,the three most common topologies of MOFs built from the organic linker p.p'-terphenyldicarboxylic acid(tpdc).To synthesize the four squaramide-based MOFs,we designed and synthesized a linker,4,4’-((3,4-dioxocyclobut-1-ene-1,2-diyl)bis(azanedyil))dibenzoic acid(Sq_tpdc),which is identical in directionality and length to tpdc but which contains organocatalytic squaramide centers.Squaramides were chosen because their immobilization into a framework enhances its reactivity and stability while avoiding any self-quenching phenomena.Therefore,the four MOFs share the same organocatalytic squaramide moiety,but confine it within distinct pore environments.We then evaluated these MOFs as heterogeneous H-bonding catalysts in organic transformations:a Friedel-Crafts alkylation and an epoxide ring-opening.Some of them exhibited good performance in both reactions but all showed distinct catalytic profiles that reflect their structural differences.
基金the Ministry of Science and Innovation (Spain)through the project PID2020-115566RB-I00.A.C.-G.,A.M.A.-E.A.N.extend their sincere appreciation to the Distinguished Scientist Fellowship Program (DSFP)at King Saud University for funding of this work+4 种基金support from the Spanish Ministry of Economy,Industry,and Competitiveness (MINECO)through a Juan de la Cierva-formación fellowship 2017 FJCI-2017-32919.J.Q.support from the Agencia Estatal de Investigación of Spain (Grants PID2019-106820RB,RTI2018-097180-B-100,and PGC2018-097018-BI00)the Junta de Castilla y León (Grants SA256P18 and SA121P20),including funding by ERDF/FEDER.J.Q.support from Universidad Complutense de Madrid and European Commision (MSCA COFUND UNA4CAREER grant.Project number 4129252)from MICINN (Spain)through the program Juan de la Cierva-Incorporación.
文摘We present a low-cost and easy-to-implement technique to fabricate large-area WS_(2) photodetector devices onto transparent and flexible polycarbonate substrates.The method relies on the deposition of large-area(in the cm scale)thin films(~30 nm thick)of WS_(2) by a recently introduced abrasion-induced method.Interdigitated electrical contacts are then deposited by thermal evaporation through a shadow mask.The photodetectors present well-balanced performances with an good trade-off between responsivity(up to 144 mA/W at a source-drain voltage of 10 V and illumination power of 1μW)and response time(down to~70µs)and a detectivity value of 10^(8) Jones.We found that the devices perform very reversibly upon several illumination and straining cycles and we found a moderate device-to-device variation.
基金Financial supports from the National Natural Science Foundation of China(NSFC)(Nos.62011530438 and 61704129)supported by the Key Research and Development Program of Shaanxi(No.2021KW-02),the fundamental Research Funds for the Central Universities(No.JB211409 and 20109215605)+6 种基金the fund of the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University(No.SKLSP201612)funding by European Research Council(ERC)through the project 2D-TOPSENSE(GA 755655)European Union's Horizon 2020 research and innovation program(Graphene Core2-Graphene-based disruptive technologies(No.881603)Graphene Core3-Graphene-based disruptive technologies(No.956813))EU FLAG-ERA through the project To2Dox(No.JTC-2019-009)the Comunidad de Madrid through the project CAIRO-CM project(No.Y2020/NMT-6661)the Spanish Ministry of Science and Innovation through the project(No.PID2020-118078RB-I00).O.Ç.acknowledges the European Union's Horizon 2020 research and innovation program under the grant agreement 956813(2Exciting).S.P.acknowledges the fellowship PRE2018-084818.
文摘Single-layer MoS_(2)produced by mechanical exfoliation is usually connected to thicker and multilayer regions.We show a facile laser trimming method to insulate single-layer MoS_(2)regions from thicker ones.We demonstrate,through electrical characterization,that the laser trimming method can be used to pattern single-layer MoS_(2)channels with regular geometry and electrically disconnected from the thicker areas.Scanning photocurrent microscope further confirms that in the as-deposited flake(connected to a multilayer area)most of the photocurrent is being generated in the thicker flake region.After laser trimming,scanning photocurrent microscopy shows how only the single-layer MoS_(2)region contributes to the photocurrent generation.The presented method is a direct-write and lithography-free(no need of resist or wet chemicals)alternative to reactive ion etching process to pattern the flakes that can be easily adopted by many research groups fabricating devices with MoS_(2) and similar twodimensional materials.
