To explore the lead-free key scientific issue in perovskite, double perovskite based on Ag Bi and Cu Bi was naturally selected as a competitive candidate due to its fascinating functional features, such as self-powere...To explore the lead-free key scientific issue in perovskite, double perovskite based on Ag Bi and Cu Bi was naturally selected as a competitive candidate due to its fascinating functional features, such as self-powered circularly polarized light detection, X-ray detection, photoluminescence and so on. However, the most challenging point is to simulate the structure and function of traditional lead-based perovskite in new double perovskite. At the same time, there are few suitable double perovskite systems with optical and electrical potential. The above two points greatly limit the competitiveness of double perovskite. In order to solve this problem, firstly, by analyzing and comparing previous studies,we used 2,2-dimethylpropan-1-aminium(abbreviated as 2,2-DPA) as the organic template to assemble materials. Solid-to-solid phase transition materials(2,2-DPA)3Bi2I91 and(2,2-DPA)3Pb2I72 were constructed. Along the path of lead-free and two-dimensional maintenance, we successfully synthesized(2,2-DPA)4AgBiI8.H_(2)O 3 and(2,2-DPA)_(4)CuBiI8.H_(2)O 4. As two typical semiconductors, 3 and 4 with narrower optical band gaps of 1.98 and 1.76 e V show obvious photo-response when the xenon lamp with intensity of 20 m W/cm^(2)is on or off, implying that they may be applied to light-harvesting and light-detecting devices. By referring to the phase transition mechanism of 1 and 2, 3 may be caused by ordered-disordered transition of the organic part, which was proven to be the first solid-to-solid phase transition material with <100>-oriented layered double perovskites with n = 1 by systematic characterization methods after dehydration for all we know. We believed that this work can provide meaningful guidance for the development of lead-free double perovskites.展开更多
Theβ-Ga_(2)O_(3)films with different thicknesses are prepared by an atomic layer deposition system.The influence of film thickness on the crystal quality is obvious,indicating that the thicker films perform better cr...Theβ-Ga_(2)O_(3)films with different thicknesses are prepared by an atomic layer deposition system.The influence of film thickness on the crystal quality is obvious,indicating that the thicker films perform better crystal quality,which is verified from x-ray diffraction(XRD)and scanning electron microscope(SEM)results.The Ga_(2)O_(3)-based solar blind photodetectors with different thicknesses are fabricated and studied.The experimental results show that the responsivity of the photodetectors increases exponentially with the increase of the film thickness.The photodetectors with inter-fingered structure based on 900 growth cyclesβ-Ga_(2)O_(3)active layers(corresponding film thickness of 58 nm)exhibit the best performances including a low dark current of 134 fA,photo-to-dark current ratio of 1.5×10^(7),photoresponsivity of 1.56 A/W,detectivity of 2.77×10^(14)Jones,and external quantum efficiency of 764.49%at a bias voltage of 10 V under 254-nm DUV illumination.The photoresponse rejection ratio(R_(254)/R_(365))is up to 1.86×10^(5).In addition,we find that the photoelectric characteristics also depend on the finger spacing of the MSM structure.As the finger spacing decreases from 50μm to10μW,the photoresponsivity,detectivity,and external quantum efficiency increase significantly.展开更多
Photoelectrical response characteristics of epitaxial graphene （EG） films on Si- and C-terminated 6H-SiC, and transferred chemical vapor deposition （CVD） graphene films on Si-terminated 6H-SiC have been investigat...Photoelectrical response characteristics of epitaxial graphene （EG） films on Si- and C-terminated 6H-SiC, and transferred chemical vapor deposition （CVD） graphene films on Si-terminated 6H-SiC have been investigated. The results show that upon illumination by a xenon lamp, the photocurrent of EG grown on Si-terminated SiC significantly increases by 147.6%, while the photocurrents of EG grown on C-terminated SiC, and transferred CVD graphene on Si-terminated SiC slightly decrease by 0.5% and 2.7%, respectively. The interfacial buffer layer between EG and Si-terminated 6H-SiC is responsible for the significant photoelectrical response of EG. Its strong photoelectrical response makes it promising for optoelectronic applications.展开更多
Hydrogen-bonded organic frameworks(HOFs)are a recent class of porous materials that have garnered considerable research interest owing to their distinctive characteristics.HOFs can be constructed through judicious sel...Hydrogen-bonded organic frameworks(HOFs)are a recent class of porous materials that have garnered considerable research interest owing to their distinctive characteristics.HOFs can be constructed through judicious selection of H-bonding motifs,which are further enforced by other weak intermolecular interactions such asπ–πstacking,van der Waals forces,and framework interpenetration.Taking advantage of these interactions,we can expand the functional field of HOFs by introducing active molecules.Recently,researchers have made substantial advancements in using HOFs for chemical sensing,catalysis,proton conduction,biological applications,and others.The low bonding energy of H-bonds allows for precise control over the concentration of ligands in solvents,forming diverse HOF structures.These varied structures offer significant advantages for producing HOFs with photo-responsive and electro-responsive properties.However,the presence of H-bonds in HOFs results in their inherent lower stability compared to metal-organic frameworks(MOFs)and covalent-organic frameworks(COFs)formed via coordination and covalent bonds,respectively.As a result,the pursuit of stable and innovative HOF materials with novel functional sites remains an ongoing challenge.This review provides an overview of recent research progress in the development of new strategies for stable HOF synthesis and applications of HOFs with stimuli-responsive properties.We first classified all synthetic methods reported to date and discussed the stable HOFs synthesized,as well as their unique properties and applications.In addition,we summarized the applications of HOFs utilizing their synergistic responses to external stimuli,including photo,electrical,pressure,and chemical stimuli.We systematically reviewed stable HOF synthesis and applications,which may lead to a deeper understanding of the structure–activity relationship for these materials and guide future HOF design.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 21991141)。
文摘To explore the lead-free key scientific issue in perovskite, double perovskite based on Ag Bi and Cu Bi was naturally selected as a competitive candidate due to its fascinating functional features, such as self-powered circularly polarized light detection, X-ray detection, photoluminescence and so on. However, the most challenging point is to simulate the structure and function of traditional lead-based perovskite in new double perovskite. At the same time, there are few suitable double perovskite systems with optical and electrical potential. The above two points greatly limit the competitiveness of double perovskite. In order to solve this problem, firstly, by analyzing and comparing previous studies,we used 2,2-dimethylpropan-1-aminium(abbreviated as 2,2-DPA) as the organic template to assemble materials. Solid-to-solid phase transition materials(2,2-DPA)3Bi2I91 and(2,2-DPA)3Pb2I72 were constructed. Along the path of lead-free and two-dimensional maintenance, we successfully synthesized(2,2-DPA)4AgBiI8.H_(2)O 3 and(2,2-DPA)_(4)CuBiI8.H_(2)O 4. As two typical semiconductors, 3 and 4 with narrower optical band gaps of 1.98 and 1.76 e V show obvious photo-response when the xenon lamp with intensity of 20 m W/cm^(2)is on or off, implying that they may be applied to light-harvesting and light-detecting devices. By referring to the phase transition mechanism of 1 and 2, 3 may be caused by ordered-disordered transition of the organic part, which was proven to be the first solid-to-solid phase transition material with <100>-oriented layered double perovskites with n = 1 by systematic characterization methods after dehydration for all we know. We believed that this work can provide meaningful guidance for the development of lead-free double perovskites.
基金Project supported by the Natural Science Basic Research Program of Shaanxi Province,China(Grant No.2022JQ-701)the Scientific Research Program Funded by Shaanxi Provincial Education Department,China(Grant No.21JK0919)。
文摘Theβ-Ga_(2)O_(3)films with different thicknesses are prepared by an atomic layer deposition system.The influence of film thickness on the crystal quality is obvious,indicating that the thicker films perform better crystal quality,which is verified from x-ray diffraction(XRD)and scanning electron microscope(SEM)results.The Ga_(2)O_(3)-based solar blind photodetectors with different thicknesses are fabricated and studied.The experimental results show that the responsivity of the photodetectors increases exponentially with the increase of the film thickness.The photodetectors with inter-fingered structure based on 900 growth cyclesβ-Ga_(2)O_(3)active layers(corresponding film thickness of 58 nm)exhibit the best performances including a low dark current of 134 fA,photo-to-dark current ratio of 1.5×10^(7),photoresponsivity of 1.56 A/W,detectivity of 2.77×10^(14)Jones,and external quantum efficiency of 764.49%at a bias voltage of 10 V under 254-nm DUV illumination.The photoresponse rejection ratio(R_(254)/R_(365))is up to 1.86×10^(5).In addition,we find that the photoelectric characteristics also depend on the finger spacing of the MSM structure.As the finger spacing decreases from 50μm to10μW,the photoresponsivity,detectivity,and external quantum efficiency increase significantly.
基金the Program for New Century Excellent Talents in University of Ministry of Education of China(Grant No.NCET-10-0291)the Startup Research Project of University of Electronic Science and Technology of China(Grant No.Y02002010301041)
文摘Photoelectrical response characteristics of epitaxial graphene （EG） films on Si- and C-terminated 6H-SiC, and transferred chemical vapor deposition （CVD） graphene films on Si-terminated 6H-SiC have been investigated. The results show that upon illumination by a xenon lamp, the photocurrent of EG grown on Si-terminated SiC significantly increases by 147.6%, while the photocurrents of EG grown on C-terminated SiC, and transferred CVD graphene on Si-terminated SiC slightly decrease by 0.5% and 2.7%, respectively. The interfacial buffer layer between EG and Si-terminated 6H-SiC is responsible for the significant photoelectrical response of EG. Its strong photoelectrical response makes it promising for optoelectronic applications.
基金Chinese Academy of Sciences(No.JCTD-2022-12 CAS youth interdisciplinary team)Y.Y.L.acknowledges the support from the National Science Foundation(No.HRD-2112554).
文摘Hydrogen-bonded organic frameworks(HOFs)are a recent class of porous materials that have garnered considerable research interest owing to their distinctive characteristics.HOFs can be constructed through judicious selection of H-bonding motifs,which are further enforced by other weak intermolecular interactions such asπ–πstacking,van der Waals forces,and framework interpenetration.Taking advantage of these interactions,we can expand the functional field of HOFs by introducing active molecules.Recently,researchers have made substantial advancements in using HOFs for chemical sensing,catalysis,proton conduction,biological applications,and others.The low bonding energy of H-bonds allows for precise control over the concentration of ligands in solvents,forming diverse HOF structures.These varied structures offer significant advantages for producing HOFs with photo-responsive and electro-responsive properties.However,the presence of H-bonds in HOFs results in their inherent lower stability compared to metal-organic frameworks(MOFs)and covalent-organic frameworks(COFs)formed via coordination and covalent bonds,respectively.As a result,the pursuit of stable and innovative HOF materials with novel functional sites remains an ongoing challenge.This review provides an overview of recent research progress in the development of new strategies for stable HOF synthesis and applications of HOFs with stimuli-responsive properties.We first classified all synthetic methods reported to date and discussed the stable HOFs synthesized,as well as their unique properties and applications.In addition,we summarized the applications of HOFs utilizing their synergistic responses to external stimuli,including photo,electrical,pressure,and chemical stimuli.We systematically reviewed stable HOF synthesis and applications,which may lead to a deeper understanding of the structure–activity relationship for these materials and guide future HOF design.
基金supported by the National Natural Science Foundation of China(12074311,11774288,11974279)the Natural Science Foundation of Shaanxi Province(2019JC-25)。
