Covalent organic framework nanosheets(CONs)with porous crystalline features and ultrathin thickness are ideal candidates as membrane building blocks to form well-defined transfer nanochannels.The formidable challenge ...Covalent organic framework nanosheets(CONs)with porous crystalline features and ultrathin thickness are ideal candidates as membrane building blocks to form well-defined transfer nanochannels.The formidable challenge behind self-supporting CONs membrane lies in weak noncovalent interlayer interactions and thus loose stacking,insufficient strength and structure stabilities.Herein,we propose the fabrication of interlayer force-strengthened freestanding CONs membrane through the electrostatic attraction bridge effect of positively-charged amino-rich CONs(CON-NH2)to negatively-charged sulfonated CONs(CON-SO_(3)H).Ultrathin and large lateral sized CON-SO_(3)H and CON-NH2 are synthesized,followed by restacking to prepare freestanding CONs membrane with CON-SO_(3)H as the membrane bulk.Benefiting from effective interlayer interconnection due to strong electrostatic interaction,the obtained CON-SO_(3)H/CON-NH2 membrane displays features of ultrahigh integrity,dense stacking,eminent water/acid/base/organic solvents stabilities and mechanical strength(109 MPa).The shortened-SO_(3)H distance contributes to construct site-continuous transfer pathways,and the deprotonated-SO_(3)H and protonated-NH2 form acid-base pairs to decrease interfacial resistance,which impart membrane superior proton conductivity of 486 mS cm^(-1)(80℃,100%RH).This interlayer force enhancement strategy offers a promising perspective on achieving densely-stacked CONs membrane with ultrahigh mechanical property and conduction performance for fuel cell application.展开更多
Due to the weak interlayer interactions,the binary Ⅲ-Ⅵ chalcogenides Ga Se can exist in several distinct polymorphs.Among them,the so-called β-and ε-phases simultaneously exhibit favorable total energies and moder...Due to the weak interlayer interactions,the binary Ⅲ-Ⅵ chalcogenides Ga Se can exist in several distinct polymorphs.Among them,the so-called β-and ε-phases simultaneously exhibit favorable total energies and moderate band gaps,which offer a good platform to explore their thermoelectric properties.Here,we demonstrate by first-principles calculations that the two systems have very similar band structures and phonon dispersions,despite different stacking sequences between adjacent layers.Interestingly,the lattice thermal conductivity of ε-GaSe is obviously lower than that of β-GaSe,which is inherently tied to stronger lattice anharmonicity caused by bonding heterogeneity.Besides,both systems exhibit higher p-type power factors due to doubly degenerate bands with weaker dispersions around the valence band maximum.As a consequence,a significantly enhanced p-type figure-of-merit of 2.1 can be realized at 700 K along the out-of-plane direction of theε-phase.展开更多
Based on the Smit-Suhl formula,we propose a universal approach for solving the magnon-magnon coupling problem in bilayer coupled systems(e.g.,antiferromagnets).This method requires only the energy expression,enabling ...Based on the Smit-Suhl formula,we propose a universal approach for solving the magnon-magnon coupling problem in bilayer coupled systems(e.g.,antiferromagnets).This method requires only the energy expression,enabling the automatic derivation of analytical expressions for the eigenmatrix elements via symbolic computation,eliminating the need for tedious manual calculations.Using this approach,we investigate the impact of magnetic hysteresis on magnon-magnon coupling in a system with interlayer Dzyaloshinskii-Moriya interaction(DMI).The magnetic hysteresis leads to an asymmetric magnetic field dependence of the resonance frequency and alters the number of degeneracy points between the pure optical and acoustic modes.Moreover,it can result in the coupling strength at the gap of the f–H phase diagram being nearly vanishing,contrary to the conventionally expected maximum.These results deepen the understanding of the effect of interlayer DMI on magnon–magnon coupling and the proposed universal method significantly streamlines the solving process of magnon–magnon coupling problems.展开更多
The weak interlayer van der Waals(vdW) interactions in two-dimensional(2D) vdW materials enable sliding ferroelectricity as an effective strategy for modulating their intrinsic properties. In this work, we systematica...The weak interlayer van der Waals(vdW) interactions in two-dimensional(2D) vdW materials enable sliding ferroelectricity as an effective strategy for modulating their intrinsic properties. In this work, we systematically investigate the influence of interlayer sliding on the electronic behavior of PtSe_(2) using density functional theory(DFT) calculations. Our results demonstrate that interlayer sliding induces a pronounced photocurrent spanning the short-wavelength infrared to visible spectral ranges. Remarkably, under an applied gate voltage, the sliding ferroelectric PtSe_(2) exhibits anomalously enhanced photovoltaic performance and an ultrahigh extinction ratio.Transmission spectral analysis reveals that this phenomenon originates from band structure modifications driven by energy-level transitions. Furthermore, the observed photocurrent enhancement via sliding ferroelectricity demonstrates universality across diverse platinum-based optoelectronic devices. This study introduces a novel paradigm for tailoring the intrinsic characteristics of 2D vdW semiconductors, expanding the design space for next-generation ferroelectric materials in advanced optoelectronic applications.展开更多
We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microsc...We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.展开更多
Moiré superlattices(MSLs) are modulated structures produced from homogeneous or heterogeneous two-dimensional layers stacked with a twist angle and/or lattice mismatch. Enriching the methods for fabricating MSL a...Moiré superlattices(MSLs) are modulated structures produced from homogeneous or heterogeneous two-dimensional layers stacked with a twist angle and/or lattice mismatch. Enriching the methods for fabricating MSL and realizing the unique emergent properties are key challenges in its investigation. Here we recommend that the spiral dislocation driven growth is another optional method for the preparation of high quality MSL samples. The spiral structure stabilizes the constant out-of-plane lattice distance, causing the variations in electronic and optical properties. Taking SnS_(2) MSL as an example, we find prominent properties including large band gap reduction(~ 0.4 e V) and enhanced optical activity. Firstprinciples calculations reveal that these unusual properties can be ascribed to the locally enhanced interlayer interaction associated with the Moiré potential modulation. We believe that the spiral dislocation driven growth would be a powerful method to expand the MSL family and broaden their scope of application.展开更多
Two-dimensional conjugated polymers(2DCPs)have received great interest in smart devices due to their unique physical properties associated with flexibility,nanosized thickness,and correlated quantum size effect.Contro...Two-dimensional conjugated polymers(2DCPs)have received great interest in smart devices due to their unique physical properties associated with flexibility,nanosized thickness,and correlated quantum size effect.Control of interlayer interactions of multilayer 2DCPs is crucial for modulating the confinement of charge carriers,heat,and photons to give remarkable properties because of the breaking of symmetry.However,to date,it is unclear how the multilayers of 2DCPs affect their physical properties.In this article,we for the first time perform a density functional theory calculation for the interlayer slipping effect on in-plane electronic properties of few-layer 2DCPs.Based on five homopolymers formed by C-C bonds with various stacking configurations beyond the inclined and serrated ones,results show that a moderate electric field causes the valence(conduction)band of few-layer 2DCPs to exhibit distinctive electrical characteristics which are dominated by the outermost two layers on hole(electron)enriched side.Analysis based on recombined molecular orbitals reveals that band properties are sensitive to the interlayer offsets when they result from the interference among multiple orbitals from each building block.This result provides a new guideline for manipulating charge transfer and spintronic properties of few-layer 2DCPs through an electric field to advance their various applications.展开更多
In this article,the interlayer shear effects on vibrational behavior of bilayer graphene(BG)are studied by using the molecular mechanics(MM)simulation.Investigation on mechanical behavior of graphenes has recently att...In this article,the interlayer shear effects on vibrational behavior of bilayer graphene(BG)are studied by using the molecular mechanics(MM)simulation.Investigation on mechanical behavior of graphenes has recently attracted because of their excellent properties.MM simulation is exploited for modeling of covalent bond in the plane of graphene layers and they are modeled as space-frame structures.The interaction between two layers is modeled by Lennard–Jones potential for not only two apposite atoms but also for all adjacent atoms.The frequencies and mode shapes for cantilever and bridged bilayer graphene as well as monolayer graphene(MG)are obtained by a finite element approach.Results show that the interlayer shear interaction has considerable effect on vibrational behavior of BG and increases the natural frequencies,because existence of horizontal forces(shear forces)that prevent the lateral displacements.It can be seen that the interaction between two layers are more considerable in second mode because the curvature and variation of displacement are higher in second mode.Also it can be found that changing of mode shapes has considerable effect on shear interaction.展开更多
With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to...With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to electrodes,of TMD heterostructure devices can be significantly tailored by employing the functional layers,called interlayer engineering.At the interface between different TMD layers,the dangling-bond states normally exist and act as traps against charge carrier flow.In this study,we propose a technique to suppress such carrier trap that uses enhanced interlayer hybridization to saturate dangling-bond states,as demonstrated in a strongly interlayer-coupled monolayer-bilayer PtSe2 heterostructure.The hybridization between the unsaturated states and the interlayer electronic states of PtSe2 significantly reduces the depth of carrier traps at the interface,as corroborated by our scanning tunnelling spectroscopic measurements and density functional theory calculations.The suppressed interfacial trap demonstrates that interlayer saturation may offer an efficient way to relay the charge flow at the interface of TMD heterostructures.Thus,this technique provides an effective way for optimizing the interface contact,the crucial issue exists in two-dimensional electronic community.展开更多
Endowing bilayer transition-metal dichalcogenides(TMDs)with tunable magnetism is significant to investigate the coupling of multiple electron degrees of freedom(DOFs).However,effectively inducing and tuning the magnet...Endowing bilayer transition-metal dichalcogenides(TMDs)with tunable magnetism is significant to investigate the coupling of multiple electron degrees of freedom(DOFs).However,effectively inducing and tuning the magnetic interaction of bilayer TMDs are still challenges.Herein,we report a strategy to tune the interlayer exchange interaction of centimeter-scale MoS2 bilayer with substitutional doping of Co ion,by introducing sulfur vacancy(V_(s))to modulate the interlayer electronic coupling.This strategy could transform the interlayer exchange interaction from antiferromagnetism(AFM)to ferromagnetism(FM),as revealed by the magnetic measurements.Experimental characterizations and theoretical calculations indicate that the enhanced magnetization is mainly because the hybridization of Co 3d band and Vs-induced impurity band alters the forms of interlayer orbital hybridizations between the partial Co atoms in upper and lower layers,and also enhances the intralayer FM.Our work paves the way for tuning the interlayer exchange interaction with defects and could be extended to other two-dimensional(2D)magnetic materials.展开更多
Ternary layered compound materials(bismuth oxyhalides and metal phosphorus trichalcogenides)stand out in electronic and optoelectronic fields due to their interesting physical properties.However,few studies focus on t...Ternary layered compound materials(bismuth oxyhalides and metal phosphorus trichalcogenides)stand out in electronic and optoelectronic fields due to their interesting physical properties.However,few studies focus on the preparation of high-quality two-dimensional(2D)BiOBr crystals with a typical layered structure,let alone their optoelectronic applications.Here,for the first time,high-quality 2D BiOBr crystals with ultrathin thicknesses(less than 10 nm)and large domain sizes(~100μm)were efficiently prepared via a modified space-confined chemical vapor deposition(SCCVD)method.It is demonstrated that a moderate amount of H2O molecules in the SCCVD system greatly promote the formation of high-quality 2D BiOBr crystals because of the strong polarity of H2O molecules.In addition,a linear relationship between the thickness of BiOBr nanosheets and Raman shift of A1g(1)mode was found.Corresponding theoretical calculations were carried out to verify the experimental data.Furthermore,the BiOBr-based photodetector was fabricated,exhibiting excellent performances with a responsivity of 12.4 A W-1 and a detectivity of 1.6×1013 Jones at 365 nm.This study paves the way for controllable preparation of high-quality 2D BiOBr crystals and implies intriguing opportunities of them in optoelectronic applications.展开更多
文摘Covalent organic framework nanosheets(CONs)with porous crystalline features and ultrathin thickness are ideal candidates as membrane building blocks to form well-defined transfer nanochannels.The formidable challenge behind self-supporting CONs membrane lies in weak noncovalent interlayer interactions and thus loose stacking,insufficient strength and structure stabilities.Herein,we propose the fabrication of interlayer force-strengthened freestanding CONs membrane through the electrostatic attraction bridge effect of positively-charged amino-rich CONs(CON-NH2)to negatively-charged sulfonated CONs(CON-SO_(3)H).Ultrathin and large lateral sized CON-SO_(3)H and CON-NH2 are synthesized,followed by restacking to prepare freestanding CONs membrane with CON-SO_(3)H as the membrane bulk.Benefiting from effective interlayer interconnection due to strong electrostatic interaction,the obtained CON-SO_(3)H/CON-NH2 membrane displays features of ultrahigh integrity,dense stacking,eminent water/acid/base/organic solvents stabilities and mechanical strength(109 MPa).The shortened-SO_(3)H distance contributes to construct site-continuous transfer pathways,and the deprotonated-SO_(3)H and protonated-NH2 form acid-base pairs to decrease interfacial resistance,which impart membrane superior proton conductivity of 486 mS cm^(-1)(80℃,100%RH).This interlayer force enhancement strategy offers a promising perspective on achieving densely-stacked CONs membrane with ultrahigh mechanical property and conduction performance for fuel cell application.
基金supported by the National Natural Science Foundation of China(Grant Nos.62074114 and 12474019)。
文摘Due to the weak interlayer interactions,the binary Ⅲ-Ⅵ chalcogenides Ga Se can exist in several distinct polymorphs.Among them,the so-called β-and ε-phases simultaneously exhibit favorable total energies and moderate band gaps,which offer a good platform to explore their thermoelectric properties.Here,we demonstrate by first-principles calculations that the two systems have very similar band structures and phonon dispersions,despite different stacking sequences between adjacent layers.Interestingly,the lattice thermal conductivity of ε-GaSe is obviously lower than that of β-GaSe,which is inherently tied to stronger lattice anharmonicity caused by bonding heterogeneity.Besides,both systems exhibit higher p-type power factors due to doubly degenerate bands with weaker dispersions around the valence band maximum.As a consequence,a significantly enhanced p-type figure-of-merit of 2.1 can be realized at 700 K along the out-of-plane direction of theε-phase.
基金supported by the National Key Research and Development Program of China (MOST)(Grant No.2022YFA1402800)the Chinese Academy of Sciences (CAS) Presidents International Fellowship Initiative (PIFI)(Grant No.2025PG0006)+3 种基金the National Natural Science Foundation of China (NSFC)(Grant Nos.51831012,12274437,and 52161160334)the CAS Project for Young Scientists in Basic Research (Grant No.YSBR-084)the CAS Youth Interdisciplinary Teamthe China Postdoctoral Science Foundation (Grant No.2025M773402)。
文摘Based on the Smit-Suhl formula,we propose a universal approach for solving the magnon-magnon coupling problem in bilayer coupled systems(e.g.,antiferromagnets).This method requires only the energy expression,enabling the automatic derivation of analytical expressions for the eigenmatrix elements via symbolic computation,eliminating the need for tedious manual calculations.Using this approach,we investigate the impact of magnetic hysteresis on magnon-magnon coupling in a system with interlayer Dzyaloshinskii-Moriya interaction(DMI).The magnetic hysteresis leads to an asymmetric magnetic field dependence of the resonance frequency and alters the number of degeneracy points between the pure optical and acoustic modes.Moreover,it can result in the coupling strength at the gap of the f–H phase diagram being nearly vanishing,contrary to the conventionally expected maximum.These results deepen the understanding of the effect of interlayer DMI on magnon–magnon coupling and the proposed universal method significantly streamlines the solving process of magnon–magnon coupling problems.
基金supported by the National Key Research and Development Program of China (Grant No. 2024YFB3211701)the National Natural Science Foundation of China (Grant Nos. T2222011, 62174026, and 12274234)+1 种基金the National Key Research and Development Program of China (Grant Nos. 2023YFB3611400 and 2019YFA0308000)the Fundamental Research Funds for the Central Universities (Grant No. 242023k30027)。
文摘The weak interlayer van der Waals(vdW) interactions in two-dimensional(2D) vdW materials enable sliding ferroelectricity as an effective strategy for modulating their intrinsic properties. In this work, we systematically investigate the influence of interlayer sliding on the electronic behavior of PtSe_(2) using density functional theory(DFT) calculations. Our results demonstrate that interlayer sliding induces a pronounced photocurrent spanning the short-wavelength infrared to visible spectral ranges. Remarkably, under an applied gate voltage, the sliding ferroelectric PtSe_(2) exhibits anomalously enhanced photovoltaic performance and an ultrahigh extinction ratio.Transmission spectral analysis reveals that this phenomenon originates from band structure modifications driven by energy-level transitions. Furthermore, the observed photocurrent enhancement via sliding ferroelectricity demonstrates universality across diverse platinum-based optoelectronic devices. This study introduces a novel paradigm for tailoring the intrinsic characteristics of 2D vdW semiconductors, expanding the design space for next-generation ferroelectric materials in advanced optoelectronic applications.
基金Financial supports by the National Natural Science Foundation of China (No. 21373269)the Fundamental Research Funds for the Central Universities and the Research Funds of Renmin University of China(No. 10XNJ047)
文摘We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes （g-CNN） by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFA1402500)the National Natural Science Foundation of China(Grant No.62125402)。
文摘Moiré superlattices(MSLs) are modulated structures produced from homogeneous or heterogeneous two-dimensional layers stacked with a twist angle and/or lattice mismatch. Enriching the methods for fabricating MSL and realizing the unique emergent properties are key challenges in its investigation. Here we recommend that the spiral dislocation driven growth is another optional method for the preparation of high quality MSL samples. The spiral structure stabilizes the constant out-of-plane lattice distance, causing the variations in electronic and optical properties. Taking SnS_(2) MSL as an example, we find prominent properties including large band gap reduction(~ 0.4 e V) and enhanced optical activity. Firstprinciples calculations reveal that these unusual properties can be ascribed to the locally enhanced interlayer interaction associated with the Moiré potential modulation. We believe that the spiral dislocation driven growth would be a powerful method to expand the MSL family and broaden their scope of application.
基金supported by the National Natural Science Foundation of China(52233010)CAS Project for Young Scientists in Basic Research(YSBR-053)。
文摘Two-dimensional conjugated polymers(2DCPs)have received great interest in smart devices due to their unique physical properties associated with flexibility,nanosized thickness,and correlated quantum size effect.Control of interlayer interactions of multilayer 2DCPs is crucial for modulating the confinement of charge carriers,heat,and photons to give remarkable properties because of the breaking of symmetry.However,to date,it is unclear how the multilayers of 2DCPs affect their physical properties.In this article,we for the first time perform a density functional theory calculation for the interlayer slipping effect on in-plane electronic properties of few-layer 2DCPs.Based on five homopolymers formed by C-C bonds with various stacking configurations beyond the inclined and serrated ones,results show that a moderate electric field causes the valence(conduction)band of few-layer 2DCPs to exhibit distinctive electrical characteristics which are dominated by the outermost two layers on hole(electron)enriched side.Analysis based on recombined molecular orbitals reveals that band properties are sensitive to the interlayer offsets when they result from the interference among multiple orbitals from each building block.This result provides a new guideline for manipulating charge transfer and spintronic properties of few-layer 2DCPs through an electric field to advance their various applications.
文摘In this article,the interlayer shear effects on vibrational behavior of bilayer graphene(BG)are studied by using the molecular mechanics(MM)simulation.Investigation on mechanical behavior of graphenes has recently attracted because of their excellent properties.MM simulation is exploited for modeling of covalent bond in the plane of graphene layers and they are modeled as space-frame structures.The interaction between two layers is modeled by Lennard–Jones potential for not only two apposite atoms but also for all adjacent atoms.The frequencies and mode shapes for cantilever and bridged bilayer graphene as well as monolayer graphene(MG)are obtained by a finite element approach.Results show that the interlayer shear interaction has considerable effect on vibrational behavior of BG and increases the natural frequencies,because existence of horizontal forces(shear forces)that prevent the lateral displacements.It can be seen that the interaction between two layers are more considerable in second mode because the curvature and variation of displacement are higher in second mode.Also it can be found that changing of mode shapes has considerable effect on shear interaction.
基金We acknowledged the financial support from the Beijing Natural Science Foundation(Nos.Z190006 and 4192054)the National Natural Science Foundation of China(Nos.61725107,11622437,61674171,11974422,61761166009,and 61888102)+3 种基金the National Key Research&Development Projects of China(Nos.2016YFA0202301,2019YFA0308000,and 2018YFE0202700)the Fundamental Research Funds for the Central Universities,China and the Research Funds of Renmin University of China(Nos.16XNLQ01 and 19XNQ025)the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB30000000 and XDB28000000)Calculations were performed at the Physics Lab of High-Performance Computing of Renmin University of China and Shanghai Supercomputer Center.
文摘With the unique properties,layered transition metal dichalcogenide(TMD)and its heterostructures exhibit great potential for applications in electronics.The electrical performance,e.g.,contact barrier and resistance to electrodes,of TMD heterostructure devices can be significantly tailored by employing the functional layers,called interlayer engineering.At the interface between different TMD layers,the dangling-bond states normally exist and act as traps against charge carrier flow.In this study,we propose a technique to suppress such carrier trap that uses enhanced interlayer hybridization to saturate dangling-bond states,as demonstrated in a strongly interlayer-coupled monolayer-bilayer PtSe2 heterostructure.The hybridization between the unsaturated states and the interlayer electronic states of PtSe2 significantly reduces the depth of carrier traps at the interface,as corroborated by our scanning tunnelling spectroscopic measurements and density functional theory calculations.The suppressed interfacial trap demonstrates that interlayer saturation may offer an efficient way to relay the charge flow at the interface of TMD heterostructures.Thus,this technique provides an effective way for optimizing the interface contact,the crucial issue exists in two-dimensional electronic community.
基金supported by the National Natural Science Foundation of China(Nos.11975234,11775225,12075243,12005227,51790491,U2032150 and U1732148)the Users with Excellence Program of Hefei Science Center CAS(Nos.2019HSC-UE002,2020HSC-UE002,2020HSC-CIP013 and 2021HSC-UE002)+1 种基金the Postdoctoral Science Foundation of China(Nos.2020M682041,2020TQ0316 and 2019M662202)the National Key Research and Development Program of China(No.2019YFA0307900)。
文摘Endowing bilayer transition-metal dichalcogenides(TMDs)with tunable magnetism is significant to investigate the coupling of multiple electron degrees of freedom(DOFs).However,effectively inducing and tuning the magnetic interaction of bilayer TMDs are still challenges.Herein,we report a strategy to tune the interlayer exchange interaction of centimeter-scale MoS2 bilayer with substitutional doping of Co ion,by introducing sulfur vacancy(V_(s))to modulate the interlayer electronic coupling.This strategy could transform the interlayer exchange interaction from antiferromagnetism(AFM)to ferromagnetism(FM),as revealed by the magnetic measurements.Experimental characterizations and theoretical calculations indicate that the enhanced magnetization is mainly because the hybridization of Co 3d band and Vs-induced impurity band alters the forms of interlayer orbital hybridizations between the partial Co atoms in upper and lower layers,and also enhances the intralayer FM.Our work paves the way for tuning the interlayer exchange interaction with defects and could be extended to other two-dimensional(2D)magnetic materials.
基金financially supported by the National Natural Science Foundation of China(11674265)the Natural Science Basic Research Project of Shaanxi Province(2018JZ6003)the Fundamental Research Funds for the Central Universities(3102019MS0402)。
文摘Ternary layered compound materials(bismuth oxyhalides and metal phosphorus trichalcogenides)stand out in electronic and optoelectronic fields due to their interesting physical properties.However,few studies focus on the preparation of high-quality two-dimensional(2D)BiOBr crystals with a typical layered structure,let alone their optoelectronic applications.Here,for the first time,high-quality 2D BiOBr crystals with ultrathin thicknesses(less than 10 nm)and large domain sizes(~100μm)were efficiently prepared via a modified space-confined chemical vapor deposition(SCCVD)method.It is demonstrated that a moderate amount of H2O molecules in the SCCVD system greatly promote the formation of high-quality 2D BiOBr crystals because of the strong polarity of H2O molecules.In addition,a linear relationship between the thickness of BiOBr nanosheets and Raman shift of A1g(1)mode was found.Corresponding theoretical calculations were carried out to verify the experimental data.Furthermore,the BiOBr-based photodetector was fabricated,exhibiting excellent performances with a responsivity of 12.4 A W-1 and a detectivity of 1.6×1013 Jones at 365 nm.This study paves the way for controllable preparation of high-quality 2D BiOBr crystals and implies intriguing opportunities of them in optoelectronic applications.
