Chiral organic-inorganic metal halide semiconductors(OIMHSs)have recently attracted numerous interests due to their unique chirality,structural tunability,and extensive physical properties.However,most reported chiral...Chiral organic-inorganic metal halide semiconductors(OIMHSs)have recently attracted numerous interests due to their unique chirality,structural tunability,and extensive physical properties.However,most reported chiral OIMHSs contain toxic lead,which will be a potential obstacle to their further applications.Herein,we successfully synthesized a novel chiral lead-free tin(IV)-based OIMHS[(R)-3-hydroxyquinuclidinium]_(2)SnCl_(6)([R-HQ]_(2)SnCl_(6)).It exhibits a wide band gap(Eg)of about 4.11 eV.Moreover,[R-HQ]_(2)SnCl6 undergoes a phase transition around 330 K(Tc)and shows distinct dielectric switching characteristics with good repeatability.This work enriches the chiral lead-free OIMHS family and stimulates further exploration of chiral lead-free OIMHS switching materials.展开更多
Multifunctional switchable materials are attracting tremendous interest because of their great application potential in signal processing,information encryption,and smart devices.Here,we reported an organic-inorganic ...Multifunctional switchable materials are attracting tremendous interest because of their great application potential in signal processing,information encryption,and smart devices.Here,we reported an organic-inorganic hybrid thermochromic ferroelastic crystal,[TMIm][CuCl_(4)](TMIm=1,1,3,3-tetramethylimidazolidinium),which undergoes two reversible phase transitions at 333 K and 419 K,respectively.Intriguingly,these three phases experience a remarkable ferroelastic-paraelastic-ferroelastic(2/m-mmm-2/m)transition,which remains relatively unexplored in ferroelastics.Moreover,the ferroelastic domains can be simultaneously switched under temperature and stress stimuli.Meanwhile,[TMIm][CuCl_(4)]exhibits thermochromic phenomenon,endowing it with extra spectral encryption possibilities during information processing.Combined with dielectric switching behavior,[TMIm][Cu Cl_(4)]are promising for practical applications in memory devices,next-generation sensors,and encryption technology.展开更多
The layered heterometallic halide perovskites, as a newly explored material, have attracted great scientific attention. As one of the representatives of perovskite, lead-free or lead-substituted perovskite materials a...The layered heterometallic halide perovskites, as a newly explored material, have attracted great scientific attention. As one of the representatives of perovskite, lead-free or lead-substituted perovskite materials are widely applied in photovoltaic, sensors, catalysis, detectors and other fields. Therefore, it is urgent to carry out more systematic exploration and expand applicable preresearch, so as to make more interesting discoveries in this new hot spot. As an interesting candidate, heterometallic compounds will introduce more structural adjustability and novel physical properties, which is the main feature to be selected as the research hotspot. Here, we reported a lead-free bilayer heterometallic Ruddlesden-Popper(RP) type perovskite, [(MACH)_(2)CsAgBiBr_(7)](MACH = cyclohexanemethylamine), which possesses a reversible phase transition at 379.6 K/375.1 K during heating-cooling cycle. Besides, it exhibits reddish-brown light emission under 365 nm, meanwhile, CIE chromaticity coordinate is(0.32, 0.45) on the yellow side and correlated color temperature is about 6000 K. Moreover, both the experimental data and theoretical calculation results suggest that [(MACH)_(2)CsAgBiBr_(7)] shows indirect semiconducting characteristics. In summary, this work will inspire the design of lead-free heterometallic perovskite materials for the application of sensors and light-emitting diodes(LEDs) fields.展开更多
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
Lead-based organic-inorganic hybrids occupy a niche in the field of optoelectronics due to exceptional semiconducting properties and potential ferroelasticity.Nevertheless,the possible toxicity of lead restricts their...Lead-based organic-inorganic hybrids occupy a niche in the field of optoelectronics due to exceptional semiconducting properties and potential ferroelasticity.Nevertheless,the possible toxicity of lead restricts their widespread application to a certain extent.Herein,two new lead-free ferroelastic semiconductors are reported:[DMMClEA]_(3)Bi_(2)Br_(9)(compound 1)and[DMMClEA]_(3)Sb_(2)Br_(9)(compound 2)(DMMClEA=N-(chloromethyl)-N,N-dimethylethylammonium),in which the inorganic framework neatly arranges with[Bi_(2)Br_(9)]^(3−)/[Sb_(2)Br_(9)]^(3−)polyhedrons shared by face,forming an A_(3)B_(2)X_(9)-type structure.Both compounds 1 and 2 possess two-step phase transitions,including a3mF2/m-type ferroelastic phase transition,based on the Aizu rule.In addition,dual dielectric switches endow the application toward sensor devices.This finding enriches A_(3)B_(2)X_(9)-type zero-dimensional hybrid ferroelastics and provides an approach to designing high-performance,lead-free perovskite semiconductors with dielectric functionality.展开更多
The title compound,tetramethylammonium nickel nitrite[(CH_3)_4Nl[Ni(NO_2)_3],has a hexagonal perovskite-type structure with formula ABX_3.It undergoes two reversible phase transitions occurring at about 409.1 and 428....The title compound,tetramethylammonium nickel nitrite[(CH_3)_4Nl[Ni(NO_2)_3],has a hexagonal perovskite-type structure with formula ABX_3.It undergoes two reversible phase transitions occurring at about 409.1 and 428.4 K,associated with dielectric transitions.DSC measurement and dielectric measurement confirm the transition.The variable-temperature X-ray structural determinations and the powder X-ray diffraction(PXRD) experiments reveal that this compound has the same space group P3 m 1(No.164) at 293 K,413 K and 438 K.The phase transitions are caused by the rotation of the[(CH_3)_4N]^+cation.展开更多
A new phase transition compound,2-methoxyanilinium perchlorate-18-crown-6(1) {(oCH3OC6H4NH3)+(18-crown-6) ClO4 },has been synthesized and separated as crystals.Differential scanning calorimetry(DSC) measurements show ...A new phase transition compound,2-methoxyanilinium perchlorate-18-crown-6(1) {(oCH3OC6H4NH3)+(18-crown-6) ClO4 },has been synthesized and separated as crystals.Differential scanning calorimetry(DSC) measurements show a pair of sharp peaks at 225 K(heating) and 210 K(cooling),indicating the phase transition is first-order.Dielectric anomalies observed at 225 K(heating)and 210 K(cooling) further confirm the phase transition.The crystal structures determined at 298 K and123 K are both triclinic in P 1.The most distinct difference between room-temperature and lowtemperature structures is the order–disorder transition of the host 18-crown-6 molecule,which is the driving force of the phase transition.展开更多
A clean and safe synthesis method of 5-(4'-methylbiphenyl-2-yl)-1H-tetrazole was found:under hydrothermal conditions,1.2 equiv.of 4'-methylbiphenyl-2-carbonitrile react with 1 equiv.of sodium azide in a mixed ...A clean and safe synthesis method of 5-(4'-methylbiphenyl-2-yl)-1H-tetrazole was found:under hydrothermal conditions,1.2 equiv.of 4'-methylbiphenyl-2-carbonitrile react with 1 equiv.of sodium azide in a mixed solvent of propane-1,2-diol/H2O,with 1.5 equiv.of ammonium chloride and 0.2 equiv.of ammonium fluoride as catalyst.After simple post-processing,the yield can be improved to 95%,and the purity of the product is 99%without further recrystallization.展开更多
Solid-state phase transitions of 4-methylanilinium perchlorate (4-CH 3 C 6 H 4 NH 3 ·ClO 4 , 1) and tetrafluoroborate (4-CH 3 C 6 H 4 - NH 3 ·BF 4 , 2) were investigated with variable-temperature X-ray singl...Solid-state phase transitions of 4-methylanilinium perchlorate (4-CH 3 C 6 H 4 NH 3 ·ClO 4 , 1) and tetrafluoroborate (4-CH 3 C 6 H 4 - NH 3 ·BF 4 , 2) were investigated with variable-temperature X-ray single-crystal structure analysis and thermal studies. Both 1 and 2 undergo first-order phase transitions and exhibit distinct dielectric anomalies at 385 and 247 K, respectively.展开更多
Position-sensitive-detectors(PSDs)based on lateral photoeffect have been widely used in diverse applications1–9,including optical engineering,aerospace and military fields.With increasing demand in long distance,low ...Position-sensitive-detectors(PSDs)based on lateral photoeffect have been widely used in diverse applications1–9,including optical engineering,aerospace and military fields.With increasing demand in long distance,low energy consumption,and weak signal sensing systems,the poor responsivity of conventional PSDs has become a bottleneck limiting their applications,for example,silicon p–n or p–i–n junctions2–5,or other materials and architectures6–10.Herein,we present a high-performance graphene-based PSDs with revolutionary interfacial amplification mechanism.Signal amplification in the order of~10^(4) has been demonstrated by utilizing the ultrahigh mobility of graphene and long lifetime of photo-induced carriers at the interface of SiO_(2)/Si.This would improve the detection limit of Si-based PSDs fromμW to nW level,without sacrificing the spatial resolution and response speed.Such interfacial amplification mechanism is compatible with current Si technology and can be easily extended to other sensing systems11,12.展开更多
The broad operating temperature range is sought for molecular ferroic materials who are expected to be applied to flexible and electronic materials.Hydrogen bonds,an effective force between molecules,are important to ...The broad operating temperature range is sought for molecular ferroic materials who are expected to be applied to flexible and electronic materials.Hydrogen bonds,an effective force between molecules,are important to regulate the molecule structure and their condition,helping a higher temperature range for ferroic materials.Here,we report a molecular perovskite ferroelastic(Me-Hdabco)Rb[BF_(4)]_(3)(Me-Hdabco=N-methyldabconium)which shows high temperature(T_(1)=322.5 K and T_(2)=381K)ferroelastic phase transitions.The ferroelastic phase transition temperature range of(Me-Hdabco)Rb[BF_(4)]_(3) is significantly increased by 71 K compared with[Meda-bco-F]Rb[BF_(4)]_(3)(Medabco-F=1-fluoro-4-methyl-1,4-diazoniabicyclo[2.2.2]octane).Structural analysis and thermal analysis demonstrate the ferroelastic phase transition is mainly attributed to dynamic cations order and disorder transformation.Therefore,new hydrogen bonds generated between cations and the Rb_(8)[BF_(4)]_(12) frame increase their intermolecular force,which is beneficial to improving the phase transition temperature.This finding has an important impact on the utilization of weak interactionforces to design and optimize functional materials.展开更多
One novel organic-inorganic hybrid supramolecular assemblies |(NDPA)(18-crown-6)]^(2+)(DMA)^+·3ClO_4^-(1),has been successfully constructed through the prominent strategies of crystal engineering(NDPA = N,N-dimet...One novel organic-inorganic hybrid supramolecular assemblies |(NDPA)(18-crown-6)]^(2+)(DMA)^+·3ClO_4^-(1),has been successfully constructed through the prominent strategies of crystal engineering(NDPA = N,N-dimethyI-1,4-phenylenediamine,DMA = dimethylamine),and characterized by IR,powder XRD and single crystal X-ray diffraction.In the structure,the supramolecular organic cations and inorganic ClO_4^- anions are arranged alternately and linked by N-O…H hydrogen bonds.It is worthy to note that the ClO_4^- are linked to form one-dimensional inorganic chain through strong NH…O hydrogen bonds along b-axis.There is no distinct dielectric anomaly in the temperaturedependent and frequency-dependent dielectric constant curves,suggesting that no phase transition exists within the measured temperature range(120-420 K).The relative displacement of cations and anions,the turned polarization of molecular electric moment and macrocyclic molecule rotator are the main factors to determine the trend of dielectric constant.展开更多
Two phase transition compounds,diethylammonium 1,5-naphthalenedisulfonate(1)and cyclohexylammonium 1,5-naphthalenedisulfonate(2),were screened from a series of organic salts based on 1,5-naphthalenedisulfonate.The pha...Two phase transition compounds,diethylammonium 1,5-naphthalenedisulfonate(1)and cyclohexylammonium 1,5-naphthalenedisulfonate(2),were screened from a series of organic salts based on 1,5-naphthalenedisulfonate.The phase transition behaviors were studied by differential scanning calorimetry,single-crystal X-ray analysis and dielectric measurements.Compounds 1 and 2 undergo phase transitions at about 202 and 148 K,respectively,accompanied by distinct dielectric changes.The origin of the phase transitions was ascribed to motional changes of the cations in the crystal lattices.展开更多
The pyndazine hexafluorophosphate[C_4H_5N_2]^+[PF_6]^-(1) undergoes a reversible phase transition around140 K,which was confirmed by the DSC measurement.Variable-temperature crystal structures determined at 293 K and ...The pyndazine hexafluorophosphate[C_4H_5N_2]^+[PF_6]^-(1) undergoes a reversible phase transition around140 K,which was confirmed by the DSC measurement.Variable-temperature crystal structures determined at 293 K and 93 K show that the compound crystallizes in the same space group P2_1/c,indicating that 1 undergoes an iso-structural phase transition.As the temperature decreases,dielectric measurement of the title compound shows no significant change around the phase transition temperature.Classic hydrogen bonds are found between molecules at 293 K and 93 l< with similar packing arrangement.The most distinct difference between the low temperature and room temperature structures is the order-disorder transition of the hexafluorophosphate anion,which is probably the driving force of the phase transition.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22175082,91856114 and 21703033).
文摘Chiral organic-inorganic metal halide semiconductors(OIMHSs)have recently attracted numerous interests due to their unique chirality,structural tunability,and extensive physical properties.However,most reported chiral OIMHSs contain toxic lead,which will be a potential obstacle to their further applications.Herein,we successfully synthesized a novel chiral lead-free tin(IV)-based OIMHS[(R)-3-hydroxyquinuclidinium]_(2)SnCl_(6)([R-HQ]_(2)SnCl_(6)).It exhibits a wide band gap(Eg)of about 4.11 eV.Moreover,[R-HQ]_(2)SnCl6 undergoes a phase transition around 330 K(Tc)and shows distinct dielectric switching characteristics with good repeatability.This work enriches the chiral lead-free OIMHS family and stimulates further exploration of chiral lead-free OIMHS switching materials.
基金supported by the National Natural Science Foundation of China(Nos.21975114,11904151 and 22105094)。
文摘Multifunctional switchable materials are attracting tremendous interest because of their great application potential in signal processing,information encryption,and smart devices.Here,we reported an organic-inorganic hybrid thermochromic ferroelastic crystal,[TMIm][CuCl_(4)](TMIm=1,1,3,3-tetramethylimidazolidinium),which undergoes two reversible phase transitions at 333 K and 419 K,respectively.Intriguingly,these three phases experience a remarkable ferroelastic-paraelastic-ferroelastic(2/m-mmm-2/m)transition,which remains relatively unexplored in ferroelastics.Moreover,the ferroelastic domains can be simultaneously switched under temperature and stress stimuli.Meanwhile,[TMIm][CuCl_(4)]exhibits thermochromic phenomenon,endowing it with extra spectral encryption possibilities during information processing.Combined with dielectric switching behavior,[TMIm][Cu Cl_(4)]are promising for practical applications in memory devices,next-generation sensors,and encryption technology.
基金financially supported by Zhejiang Normal Universitythe National Natural Science Foundation of China (21991141)the Natural Science Foundation of Zhejiang Province (LZ20B010001)。
基金supported by the National Natural Science Foundation of China (No. 21991141)Zhejiang Normal University。
文摘The layered heterometallic halide perovskites, as a newly explored material, have attracted great scientific attention. As one of the representatives of perovskite, lead-free or lead-substituted perovskite materials are widely applied in photovoltaic, sensors, catalysis, detectors and other fields. Therefore, it is urgent to carry out more systematic exploration and expand applicable preresearch, so as to make more interesting discoveries in this new hot spot. As an interesting candidate, heterometallic compounds will introduce more structural adjustability and novel physical properties, which is the main feature to be selected as the research hotspot. Here, we reported a lead-free bilayer heterometallic Ruddlesden-Popper(RP) type perovskite, [(MACH)_(2)CsAgBiBr_(7)](MACH = cyclohexanemethylamine), which possesses a reversible phase transition at 379.6 K/375.1 K during heating-cooling cycle. Besides, it exhibits reddish-brown light emission under 365 nm, meanwhile, CIE chromaticity coordinate is(0.32, 0.45) on the yellow side and correlated color temperature is about 6000 K. Moreover, both the experimental data and theoretical calculation results suggest that [(MACH)_(2)CsAgBiBr_(7)] shows indirect semiconducting characteristics. In summary, this work will inspire the design of lead-free heterometallic perovskite materials for the application of sensors and light-emitting diodes(LEDs) fields.
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financially supported by the National Natural Science Foundation of China(grant no.21991141).
文摘Lead-based organic-inorganic hybrids occupy a niche in the field of optoelectronics due to exceptional semiconducting properties and potential ferroelasticity.Nevertheless,the possible toxicity of lead restricts their widespread application to a certain extent.Herein,two new lead-free ferroelastic semiconductors are reported:[DMMClEA]_(3)Bi_(2)Br_(9)(compound 1)and[DMMClEA]_(3)Sb_(2)Br_(9)(compound 2)(DMMClEA=N-(chloromethyl)-N,N-dimethylethylammonium),in which the inorganic framework neatly arranges with[Bi_(2)Br_(9)]^(3−)/[Sb_(2)Br_(9)]^(3−)polyhedrons shared by face,forming an A_(3)B_(2)X_(9)-type structure.Both compounds 1 and 2 possess two-step phase transitions,including a3mF2/m-type ferroelastic phase transition,based on the Aizu rule.In addition,dual dielectric switches endow the application toward sensor devices.This finding enriches A_(3)B_(2)X_(9)-type zero-dimensional hybrid ferroelastics and provides an approach to designing high-performance,lead-free perovskite semiconductors with dielectric functionality.
基金This work was supported by National Natural Science Foundation of China （Nos. 61422503, 21541013 and 61376104）, Natural Science Foundation of Jiangsu Province （No. BK20150596）, Jiangsu key laboratory for advanced metallic materials （No. BM2007204）, the open research funds of Key Laboratory of MEMS of Ministry of Education （SEU, China）, and the Funda- mental Research Funds for the Central Universities. The authors would like to thank Prof. Zhenhua Qiao from USTC, China for helpful discussions.
基金supported by the Project 973(No. 2014CB848800)National Natural Science Foundation of China (Nos.91022003 and 21301029)+1 种基金Jiangsu Province NSF(No. BK20130600)Program for NCET and Ph.D.Programs Foundation of Ministry of Education of China(No.20130092120013)
文摘The title compound,tetramethylammonium nickel nitrite[(CH_3)_4Nl[Ni(NO_2)_3],has a hexagonal perovskite-type structure with formula ABX_3.It undergoes two reversible phase transitions occurring at about 409.1 and 428.4 K,associated with dielectric transitions.DSC measurement and dielectric measurement confirm the transition.The variable-temperature X-ray structural determinations and the powder X-ray diffraction(PXRD) experiments reveal that this compound has the same space group P3 m 1(No.164) at 293 K,413 K and 438 K.The phase transitions are caused by the rotation of the[(CH_3)_4N]^+cation.
基金supported by the National Natural Science Foundation of China (No. 21101025)
文摘A new phase transition compound,2-methoxyanilinium perchlorate-18-crown-6(1) {(oCH3OC6H4NH3)+(18-crown-6) ClO4 },has been synthesized and separated as crystals.Differential scanning calorimetry(DSC) measurements show a pair of sharp peaks at 225 K(heating) and 210 K(cooling),indicating the phase transition is first-order.Dielectric anomalies observed at 225 K(heating)and 210 K(cooling) further confirm the phase transition.The crystal structures determined at 298 K and123 K are both triclinic in P 1.The most distinct difference between room-temperature and lowtemperature structures is the order–disorder transition of the host 18-crown-6 molecule,which is the driving force of the phase transition.
基金supported by the National Natural Science Foundations of China(Nos.21101026,20931002,20921004,90922005 and 91022003)
文摘A clean and safe synthesis method of 5-(4'-methylbiphenyl-2-yl)-1H-tetrazole was found:under hydrothermal conditions,1.2 equiv.of 4'-methylbiphenyl-2-carbonitrile react with 1 equiv.of sodium azide in a mixed solvent of propane-1,2-diol/H2O,with 1.5 equiv.of ammonium chloride and 0.2 equiv.of ammonium fluoride as catalyst.After simple post-processing,the yield can be improved to 95%,and the purity of the product is 99%without further recrystallization.
基金supported by the National Natural Science Foundation of China (21071030)Natural Science Foundation of Jiangsu Province(BK2010425)
文摘Solid-state phase transitions of 4-methylanilinium perchlorate (4-CH 3 C 6 H 4 NH 3 ·ClO 4 , 1) and tetrafluoroborate (4-CH 3 C 6 H 4 - NH 3 ·BF 4 , 2) were investigated with variable-temperature X-ray single-crystal structure analysis and thermal studies. Both 1 and 2 undergo first-order phase transitions and exhibit distinct dielectric anomalies at 385 and 247 K, respectively.
基金supported by the National Key Research and Development Program of China(No.2017YFA0205700)NSFC(61774034,61422503 and 61376104)the Fundamental Research Funds for the Central Universities,and Research and Innovation Project for College Graduates of Jiangsu Province No.KYLX15_0111.
文摘Position-sensitive-detectors(PSDs)based on lateral photoeffect have been widely used in diverse applications1–9,including optical engineering,aerospace and military fields.With increasing demand in long distance,low energy consumption,and weak signal sensing systems,the poor responsivity of conventional PSDs has become a bottleneck limiting their applications,for example,silicon p–n or p–i–n junctions2–5,or other materials and architectures6–10.Herein,we present a high-performance graphene-based PSDs with revolutionary interfacial amplification mechanism.Signal amplification in the order of~10^(4) has been demonstrated by utilizing the ultrahigh mobility of graphene and long lifetime of photo-induced carriers at the interface of SiO_(2)/Si.This would improve the detection limit of Si-based PSDs fromμW to nW level,without sacrificing the spatial resolution and response speed.Such interfacial amplification mechanism is compatible with current Si technology and can be easily extended to other sensing systems11,12.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2017YFA0204800)and Southeast University。
文摘The broad operating temperature range is sought for molecular ferroic materials who are expected to be applied to flexible and electronic materials.Hydrogen bonds,an effective force between molecules,are important to regulate the molecule structure and their condition,helping a higher temperature range for ferroic materials.Here,we report a molecular perovskite ferroelastic(Me-Hdabco)Rb[BF_(4)]_(3)(Me-Hdabco=N-methyldabconium)which shows high temperature(T_(1)=322.5 K and T_(2)=381K)ferroelastic phase transitions.The ferroelastic phase transition temperature range of(Me-Hdabco)Rb[BF_(4)]_(3) is significantly increased by 71 K compared with[Meda-bco-F]Rb[BF_(4)]_(3)(Medabco-F=1-fluoro-4-methyl-1,4-diazoniabicyclo[2.2.2]octane).Structural analysis and thermal analysis demonstrate the ferroelastic phase transition is mainly attributed to dynamic cations order and disorder transformation.Therefore,new hydrogen bonds generated between cations and the Rb_(8)[BF_(4)]_(12) frame increase their intermolecular force,which is beneficial to improving the phase transition temperature.This finding has an important impact on the utilization of weak interactionforces to design and optimize functional materials.
基金financially supported by the 973 Project(No. 2014CB848800)National Natural Science Foundation of China (Nos.21422101 and 21301029)+1 种基金Jiangsu Province NSF(Nos. BK20140056 and BK20130600)Program for NCET and Ph.D. Programs Foundation of Ministry of Education of China(No. 20130092120013)
文摘One novel organic-inorganic hybrid supramolecular assemblies |(NDPA)(18-crown-6)]^(2+)(DMA)^+·3ClO_4^-(1),has been successfully constructed through the prominent strategies of crystal engineering(NDPA = N,N-dimethyI-1,4-phenylenediamine,DMA = dimethylamine),and characterized by IR,powder XRD and single crystal X-ray diffraction.In the structure,the supramolecular organic cations and inorganic ClO_4^- anions are arranged alternately and linked by N-O…H hydrogen bonds.It is worthy to note that the ClO_4^- are linked to form one-dimensional inorganic chain through strong NH…O hydrogen bonds along b-axis.There is no distinct dielectric anomaly in the temperaturedependent and frequency-dependent dielectric constant curves,suggesting that no phase transition exists within the measured temperature range(120-420 K).The relative displacement of cations and anions,the turned polarization of molecular electric moment and macrocyclic molecule rotator are the main factors to determine the trend of dielectric constant.
基金financially supported by the National Natural Science Foundation of China(21991141)the Natural Science Foundation of Zhejiang Province(LZ20B010001)Zhejiang Normal University。
基金the National Natural Science Foundation of China (21225102)
文摘Two phase transition compounds,diethylammonium 1,5-naphthalenedisulfonate(1)and cyclohexylammonium 1,5-naphthalenedisulfonate(2),were screened from a series of organic salts based on 1,5-naphthalenedisulfonate.The phase transition behaviors were studied by differential scanning calorimetry,single-crystal X-ray analysis and dielectric measurements.Compounds 1 and 2 undergo phase transitions at about 202 and 148 K,respectively,accompanied by distinct dielectric changes.The origin of the phase transitions was ascribed to motional changes of the cations in the crystal lattices.
基金financially supported by the National Natural Science Foundation of China(No.91222101)
文摘The pyndazine hexafluorophosphate[C_4H_5N_2]^+[PF_6]^-(1) undergoes a reversible phase transition around140 K,which was confirmed by the DSC measurement.Variable-temperature crystal structures determined at 293 K and 93 K show that the compound crystallizes in the same space group P2_1/c,indicating that 1 undergoes an iso-structural phase transition.As the temperature decreases,dielectric measurement of the title compound shows no significant change around the phase transition temperature.Classic hydrogen bonds are found between molecules at 293 K and 93 l< with similar packing arrangement.The most distinct difference between the low temperature and room temperature structures is the order-disorder transition of the hexafluorophosphate anion,which is probably the driving force of the phase transition.
