The Peierls structural transition in quasi-one-dimensional organic crystals of TTF-TCNQ is investigated in the frame of a more complete physical model. The two most important electron-phonon interaction mechanisms are...The Peierls structural transition in quasi-one-dimensional organic crystals of TTF-TCNQ is investigated in the frame of a more complete physical model. The two most important electron-phonon interaction mechanisms are taken into account simultaneously. One is similar of that of deformation potential and the other is of polaron type. For simplicity, the 2D crystal model is considered. The renormalized phonon spectrum and the phonon polarization operator are calculated in the random phase approximation for different temperatures. The effects of interchain interaction on renormalized acoustic phonons and on the Peierls critical temperature are analyzed.展开更多
The Peierls structural transition in the TTT<sub>2</sub>I<sub>3</sub> (tetrathiotetracene-iodide) crystal, for different values of carrier concentration is studied in 3D approximation. A crysta...The Peierls structural transition in the TTT<sub>2</sub>I<sub>3</sub> (tetrathiotetracene-iodide) crystal, for different values of carrier concentration is studied in 3D approximation. A crystal physical model is applied that considers two of the most important hole-phonon interactions. The first interaction describes the deformation potential and the second one is of polaron type. In the presented physical model, the interaction of carriers with the structural defects is taken into account. This is crucial for the explanation of the transition. The renormalized phonon spectrum is calculated in the random phase approximation for different temperatures applying the method of Green functions. The renormalized phonon frequencies for different temperatures are presented in two cases. In the first case the interaction between TTT chains is neglected. In the second one, this interaction is taken into account. Computer simulations for the 3D physical model of the TTT<sub>2</sub>I<sub>3</sub> crystal are performed for different values of dimensionless Fermi momentum <em>k</em><sub>F</sub>, that is determined by variation of carrier concentration. It is shown that the transition is of Peierls type and strongly depends on iodine concentration. Finally, the Peierls critical temperature was determined.展开更多
The structure type for the crystal of 4,4'-bis-(2-hydroxy-ethoxyl)-biphenyl 1 has been predicted by using the previously developed interfacial model for small organic molecules. Based on the calculated hydrophobic...The structure type for the crystal of 4,4'-bis-(2-hydroxy-ethoxyl)-biphenyl 1 has been predicted by using the previously developed interfacial model for small organic molecules. Based on the calculated hydrophobic to hydrophilic volume of 1, this model predicts the crystal structure to be of lamellar or bicontinuous type, which has been confirmed by the X-ray single-crystal structure analysis (C20H26O6, monoclinic, P21/C, a = 16.084(1), b = 6.0103(4), c = 9.6410(7) A, β9 = 103.014(2)°, V= 908.1(1) A3, Z = 2, Dc= 1.325 g/cm3, F(000)=388,μ = 0.097 mm-1, MoKα radiation, λ = 0.71073 A, R = 0.0382 and wR = 0.0882 with I > 2σ(I) for 7121 reflections collected, 1852 unique reflections and 170 parameters). As predicted, the hydrophobic and hydrophilic portions of 1 form in the lamellae. The same interfacial model is applied to other amphilphilic small molecule organic systems for structural type prediction.展开更多
Abundant high-performance organic crystals have been reported in the past decades;however,applications of crystalline materials are seriously restricted by their notorious brittleness.Recently,some organic crystals ha...Abundant high-performance organic crystals have been reported in the past decades;however,applications of crystalline materials are seriously restricted by their notorious brittleness.Recently,some organic crystals have been designed to be deformable in response to stress,light,heat,or humidity;nevertheless,the development of flexible organic crystals currently relies on a molecular framework design.So far there is no effective strategy for constructing organic crystals with tunable flexibility based on the same luminescent skeleton.Herein,we propose a side-chain engineering strategy aimed at facilely modulating the mechanical compliance of organic crystals.Subtly changing the side chains of a single-benzeneπ-skeleton greatly alters the mechanical behaviors while maintaining the unique optical functions of the produced crystals.Optical waveguides and amplified spontaneous emissions were measured to evaluate the application potentials of the flexible crystals as soft optical transducing media.We anticipate that the proposed strategy will be expanded to regulate the mechanical compliance of other organic crystals with unique emission properties.In addition,the applications attempted preliminarily here highlight the superiority of“crystal flexibility”in flexible optoelectronics for some special application scenarios that require complex and shape changeable optical circuits.展开更多
Organic ionic plastic crystals(OIPCs)are emerging as an important material family for solid-state electrolytes and many other applications.They have significant advantages over conventional electrolyte materials,such ...Organic ionic plastic crystals(OIPCs)are emerging as an important material family for solid-state electrolytes and many other applications.They have significant advantages over conventional electrolyte materials,such as high ionic conductivity,non-flammability,and plasticity.Various nuclear magnetic resonance(NMR)spectroscopy techniques including solid-state NMR,pulsed-field gradient(PFG)NMR,and magnetic resonance imaging(MRI)etc.,provide us a versatile toolkit to understand the fundamental level structures,molecular dynamics,and ionic interactions in these materials.This article reviews the commonly used NMR methods including solid-and solution-state NMR,PFG-NMR,dynamic nuclear polarization(DNP)and the application of these methods in revealing the microscopic level structures and ion-transport mechanisms in OIPC materials.展开更多
The distribution of crystal organic fertilizer, urea and compound fertilizer-N in soil and plant system was researched with 15N-trace under tobacco pot experiment. The results showed that the leaf yield of tobacco use...The distribution of crystal organic fertilizer, urea and compound fertilizer-N in soil and plant system was researched with 15N-trace under tobacco pot experiment. The results showed that the leaf yield of tobacco used crystal organic fertilizer was 23.1% and 14.6% higher than that of urea and compound fertilizer treatments respectively. Compound fertilizer also resulted in higher yield of 8.5 % comparing with the urea treatment. Nitrogen content of the plant from the crystal organic fertilizer treatment was 138. 6% and 145.7% as high as that of the compound fertilizer and urea treatments respectively. The absorbed N from the organic fertilizer was 25.1% and 27.9% more than that from the compound fertilizer and urea respectively. However, the absorbed N from the soil with the organic fertilizer was 47.4% and 58.3% more than that with compound fertilizer and urea respectively. The N use efficiency of the organic fertilizer was 9.4% and 10.1% higher than that of the compound fertilizer and urea. It indicated that the crystal organic fertilizer not only had high N use efficiency, but also stimulated tobacco taking up more N from soil.展开更多
Large crystal NPP-OTs has been obtained by growth from solution,its powder SHG efficiency is 1/3 of urea.It shows it is a new convenient approach to obtain organic second-order NLO crystal:the dipole-dipole interactio...Large crystal NPP-OTs has been obtained by growth from solution,its powder SHG efficiency is 1/3 of urea.It shows it is a new convenient approach to obtain organic second-order NLO crystal:the dipole-dipole interaction is oppos- ed by introducing a large side group.展开更多
Most irradiation studies in the hydrogen bonded ferroelectrics have been concentrated on the transient defects induced by ionising radiation, such as ultraviolet (UV) light, where the defects are closely related to ...Most irradiation studies in the hydrogen bonded ferroelectrics have been concentrated on the transient defects induced by ionising radiation, such as ultraviolet (UV) light, where the defects are closely related to the optical properties. But heavy ion beam irradiation effects have rarely been studied. The structural, optical, and non-linear optical properties of the doped crystals were analyzed with the characterization studies, such as powder XRD, UV-Visible and second harmonic generation (SHG) measurements, respectively. The results for doped KDP crystal were compared with the results of the pure KDP crystals. The experiment results showed that Li^3+ irradiation leads to the development of a well-defined surface H peak in dye doped KDP crystals. The stability of KDP single crystal was improved by doping organic dyes. The nano-islands of dye in KDP were likely to be dissolved and enhance the non-linear optical properties of these materials.展开更多
The most simple method for solventless synthesis of supramolecular complex of CMCR·2BPY·BZP, [CMCR = C-methylcalix[4]resorcinarene, BPY = 4,4'-bipyridine, BZP = benzophenone], is proposed. Although CMCR ...The most simple method for solventless synthesis of supramolecular complex of CMCR·2BPY·BZP, [CMCR = C-methylcalix[4]resorcinarene, BPY = 4,4'-bipyridine, BZP = benzophenone], is proposed. Although CMCR by itself is high melting point compound (above 300°C), CMCR was found to be dissolved in melt mixture of BPY and BZPeven below 120°C. In the mixture of the three components, the reaction occurs to form CMCR·2BPY·BZP supramolecular complex.展开更多
Uniform and well-aligned organic semiconductor single crystals(OSSCs)are critical for high-performance electronic and optoelectronic device applications due to their long-range order and low defect density.However,it ...Uniform and well-aligned organic semiconductor single crystals(OSSCs)are critical for high-performance electronic and optoelectronic device applications due to their long-range order and low defect density.However,it is still challenging to fabricate uniform and well-aligned OSSCs by an efficient and facile method.Here,we report a vapor-induced coating method to prepare uniform organic semiconductor stripe single crystals with well-aligned orientation.The coating velocity and solution concentration are important to control the stripe crystals’morphology,which influence the triple-phase contact line dewetting behavior and then change the mass transport of the meniscus.Insufficient solute supply causes the generation of dendritic crystals.Uniform stripe single crystals of high quality and pure orientation are prepared in the condition of a sufficient and suitable solute supply.Moreover,the electronic and optoelectronic properties are evaluated.Notably,the polarization-sensitive photodetectors based on the uniform stripe crystals exhibit high polarization sensitivity and its dichroic ratio of photocurrent is 1.98.This method is efficient for the preparation of various high-quality and uniform organic semiconductor stripe single crystals,opening an opportunity for high-performance organic functional devices.展开更多
Multicomponent self-assembled chiral systems have attracted great attention due to their promising application in the area of spin-photonics and optoelectronics.In this work,through introducing an achiral third compon...Multicomponent self-assembled chiral systems have attracted great attention due to their promising application in the area of spin-photonics and optoelectronics.In this work,through introducing an achiral third component into an achiral binary crystal,a chiral organic ternary crystal is fabricated,where both pronounced chiral-optical coupling and magnetic field dependence of chiral-optical activities are observed.The transformation of achiral structure into chiral structure generates a significant effect on the polarized state of light and the electron spin resonance signals.Moreover,the coupling between circularly polarized photon and spin is observed in chiral ternary crystal with pronounced chiral orbit,where obvious magnetic field-transmissivity loop is generated.Furthermore,temperature could increase the magnitude of lattice parameters to lead to a larger helix radius to increase the chiral orbit effect.Overall,this work indicates that the further exploration of photon-chiral orbit-spin interactions in organic chiral ternary crystals is promising.展开更多
Process of crystal growth can be controlled by both surface kinetics and by volume transport as well.Although the complicated relation between the surface kinetics and volume transport exsits,generally,they are studie...Process of crystal growth can be controlled by both surface kinetics and by volume transport as well.Although the complicated relation between the surface kinetics and volume transport exsits,generally,they are studied seprately.Due to the mathematical complexity of heat and mass transport equations,the in depth studies of heat and mass transport process become difficult.Most of the studies on the transport were performed for the growth from melt.Most of the work on Surface kinetics has been done for crystal growth from aqueous solution because the in situ observation of crystal growth is easily carried out.In recent years,the surface kinetics studies on the nanometer scale,even atomic scale,are demonstrated by using AFM.展开更多
The dilemma for the synthesis of covalent organic frameworks(COFs)is crystallinity and stability.Herein,we present the synthesis of a single-crystalline amide-linked COF,and demonstrate its excellent chemical as well ...The dilemma for the synthesis of covalent organic frameworks(COFs)is crystallinity and stability.Herein,we present the synthesis of a single-crystalline amide-linked COF,and demonstrate its excellent chemical as well as thermal stabilities.This study will inspire the synthesis of a wide spectrum of highly crystalline and stable COFs,promote their structure-property investigations and boost their applications in selective gas adsorption,storage and separation.展开更多
This paper reports that a charge-transfer salt dibutylammonium bis-7,7,8,8-tetraeyanoquinodimethane [DBA (TCNQ)2] has been prepared. The temperature dependences of the DC electrical conductivity of the DBA (TCNQ)2...This paper reports that a charge-transfer salt dibutylammonium bis-7,7,8,8-tetraeyanoquinodimethane [DBA (TCNQ)2] has been prepared. The temperature dependences of the DC electrical conductivity of the DBA (TCNQ)2 single crystal measured along the crystallographic a, b, and c axes are reported. The crystal shows semicondueting behaviour and the room-temperature conductivities are highly anisotropic (σa = 3.63× 10^-4S/cm, σb = 2.84× 10^-6S/cm, and (σe = 1.82 × 10^-5S/cm). Particularly, a sharp semiconductor to semiconductor transition has been observed around 270 K on the resistivity curves measured under cooling and heating. In addition, thermal hysteresis phenomena on conductivity and differential scanning calorimetry curves are also reported.展开更多
Organic field-effect transistors are of great importance to electronic devices.With the emergence of various preparation techniques for organic semiconductor materials,the device performance has been improved remarkab...Organic field-effect transistors are of great importance to electronic devices.With the emergence of various preparation techniques for organic semiconductor materials,the device performance has been improved remarkably.Among all of the organic materials,single crystals are potentially promising for high performances due to high purity and well-ordered molecular arrangement.Based on organic single crystals,alignment and patterning techniques are essential for practical industrial application of electronic devices.In this review,recently developed methods for crystal alignment and patterning are described.展开更多
Growth of two-dimensional(2D)organic single crystals(2DOSCs)on water surface has attracted increasing attention,because it can serve as a molecularly flat and defect-free substrate.However,large-area growth of 2DOSCs ...Growth of two-dimensional(2D)organic single crystals(2DOSCs)on water surface has attracted increasing attention,because it can serve as a molecularly flat and defect-free substrate.However,large-area growth of 2DOSCs with controllable crystal orientation on water surface remains a key challenge.Herein,we develop a simple method,i.e.external-force-driven solution epitaxy(EFDSE),for the large-area growth of 2DOSCs at air/water interface.Using 2,7-didecylbenzothienobenzothiophene(C1o-BTBT)as an example,high-quality 2D C10-BTBT crystals on centimeter scale are generated by directionally controlling the spreading of organic solution on water surface with external force.Benefiting from the controllable crystal orientation with optimal charge transport,the corresponding 2DOSC-based organic field-effect transistors(OFETs)exhibit a high carrier mobility of 13.5 cm^2·V^-1·s^-1(effective mobility=5.4 cm^2·V^-1·s^-1 according to a reliability factor of 40%),which represents the best result achieved for water-surface-assembled 2DOSC based OFETs.Furthermore,by transterring the C1o-BTBT 2DOSCs to flexible substrates,devices with excellent bending stability are achieved.It is anticipated that our method will provide new insight into the controllable growth of large-area 2DOSCs for high-performance organic devices.展开更多
Polyacrylate-based conductive coatings were prepared from polyacrylate emulsion as matrix and carbon black (CB) whose surface was treated with titanate coupling agent as conducting particles.One kind of organic crysta...Polyacrylate-based conductive coatings were prepared from polyacrylate emulsion as matrix and carbon black (CB) whose surface was treated with titanate coupling agent as conducting particles.One kind of organic crystal was added to study its effects on the electrical conductivity and PTC(positive temperature coefficient)effect of the conductive coatings.Experimental results show that the coatings containing only polyacrylate emulsion and CB exhibit an excellent electrical conductivity but bad PTC effect,and when organic crystal is added,PTC effect is characterized and can increase by 2 orders of magtitude.The critical transformation temperature of polyacrylate emulsion/CB PTC composites is decided by melting point of organic crystals.展开更多
文摘The Peierls structural transition in quasi-one-dimensional organic crystals of TTF-TCNQ is investigated in the frame of a more complete physical model. The two most important electron-phonon interaction mechanisms are taken into account simultaneously. One is similar of that of deformation potential and the other is of polaron type. For simplicity, the 2D crystal model is considered. The renormalized phonon spectrum and the phonon polarization operator are calculated in the random phase approximation for different temperatures. The effects of interchain interaction on renormalized acoustic phonons and on the Peierls critical temperature are analyzed.
文摘The Peierls structural transition in the TTT<sub>2</sub>I<sub>3</sub> (tetrathiotetracene-iodide) crystal, for different values of carrier concentration is studied in 3D approximation. A crystal physical model is applied that considers two of the most important hole-phonon interactions. The first interaction describes the deformation potential and the second one is of polaron type. In the presented physical model, the interaction of carriers with the structural defects is taken into account. This is crucial for the explanation of the transition. The renormalized phonon spectrum is calculated in the random phase approximation for different temperatures applying the method of Green functions. The renormalized phonon frequencies for different temperatures are presented in two cases. In the first case the interaction between TTT chains is neglected. In the second one, this interaction is taken into account. Computer simulations for the 3D physical model of the TTT<sub>2</sub>I<sub>3</sub> crystal are performed for different values of dimensionless Fermi momentum <em>k</em><sub>F</sub>, that is determined by variation of carrier concentration. It is shown that the transition is of Peierls type and strongly depends on iodine concentration. Finally, the Peierls critical temperature was determined.
基金This work was supported by the National Science Foundation(Grant DMR-9812351)
文摘The structure type for the crystal of 4,4'-bis-(2-hydroxy-ethoxyl)-biphenyl 1 has been predicted by using the previously developed interfacial model for small organic molecules. Based on the calculated hydrophobic to hydrophilic volume of 1, this model predicts the crystal structure to be of lamellar or bicontinuous type, which has been confirmed by the X-ray single-crystal structure analysis (C20H26O6, monoclinic, P21/C, a = 16.084(1), b = 6.0103(4), c = 9.6410(7) A, β9 = 103.014(2)°, V= 908.1(1) A3, Z = 2, Dc= 1.325 g/cm3, F(000)=388,μ = 0.097 mm-1, MoKα radiation, λ = 0.71073 A, R = 0.0382 and wR = 0.0882 with I > 2σ(I) for 7121 reflections collected, 1852 unique reflections and 170 parameters). As predicted, the hydrophobic and hydrophilic portions of 1 form in the lamellae. The same interfacial model is applied to other amphilphilic small molecule organic systems for structural type prediction.
基金supported by the National Natural Science Foundation of China(grant no.52173164).
文摘Abundant high-performance organic crystals have been reported in the past decades;however,applications of crystalline materials are seriously restricted by their notorious brittleness.Recently,some organic crystals have been designed to be deformable in response to stress,light,heat,or humidity;nevertheless,the development of flexible organic crystals currently relies on a molecular framework design.So far there is no effective strategy for constructing organic crystals with tunable flexibility based on the same luminescent skeleton.Herein,we propose a side-chain engineering strategy aimed at facilely modulating the mechanical compliance of organic crystals.Subtly changing the side chains of a single-benzeneπ-skeleton greatly alters the mechanical behaviors while maintaining the unique optical functions of the produced crystals.Optical waveguides and amplified spontaneous emissions were measured to evaluate the application potentials of the flexible crystals as soft optical transducing media.We anticipate that the proposed strategy will be expanded to regulate the mechanical compliance of other organic crystals with unique emission properties.In addition,the applications attempted preliminarily here highlight the superiority of“crystal flexibility”in flexible optoelectronics for some special application scenarios that require complex and shape changeable optical circuits.
基金Guangdong Basic and Applied Basic Research Found ation(Guangdong Province,China)general project for the financial support。
文摘Organic ionic plastic crystals(OIPCs)are emerging as an important material family for solid-state electrolytes and many other applications.They have significant advantages over conventional electrolyte materials,such as high ionic conductivity,non-flammability,and plasticity.Various nuclear magnetic resonance(NMR)spectroscopy techniques including solid-state NMR,pulsed-field gradient(PFG)NMR,and magnetic resonance imaging(MRI)etc.,provide us a versatile toolkit to understand the fundamental level structures,molecular dynamics,and ionic interactions in these materials.This article reviews the commonly used NMR methods including solid-and solution-state NMR,PFG-NMR,dynamic nuclear polarization(DNP)and the application of these methods in revealing the microscopic level structures and ion-transport mechanisms in OIPC materials.
文摘The distribution of crystal organic fertilizer, urea and compound fertilizer-N in soil and plant system was researched with 15N-trace under tobacco pot experiment. The results showed that the leaf yield of tobacco used crystal organic fertilizer was 23.1% and 14.6% higher than that of urea and compound fertilizer treatments respectively. Compound fertilizer also resulted in higher yield of 8.5 % comparing with the urea treatment. Nitrogen content of the plant from the crystal organic fertilizer treatment was 138. 6% and 145.7% as high as that of the compound fertilizer and urea treatments respectively. The absorbed N from the organic fertilizer was 25.1% and 27.9% more than that from the compound fertilizer and urea respectively. However, the absorbed N from the soil with the organic fertilizer was 47.4% and 58.3% more than that with compound fertilizer and urea respectively. The N use efficiency of the organic fertilizer was 9.4% and 10.1% higher than that of the compound fertilizer and urea. It indicated that the crystal organic fertilizer not only had high N use efficiency, but also stimulated tobacco taking up more N from soil.
文摘Large crystal NPP-OTs has been obtained by growth from solution,its powder SHG efficiency is 1/3 of urea.It shows it is a new convenient approach to obtain organic second-order NLO crystal:the dipole-dipole interaction is oppos- ed by introducing a large side group.
文摘Most irradiation studies in the hydrogen bonded ferroelectrics have been concentrated on the transient defects induced by ionising radiation, such as ultraviolet (UV) light, where the defects are closely related to the optical properties. But heavy ion beam irradiation effects have rarely been studied. The structural, optical, and non-linear optical properties of the doped crystals were analyzed with the characterization studies, such as powder XRD, UV-Visible and second harmonic generation (SHG) measurements, respectively. The results for doped KDP crystal were compared with the results of the pure KDP crystals. The experiment results showed that Li^3+ irradiation leads to the development of a well-defined surface H peak in dye doped KDP crystals. The stability of KDP single crystal was improved by doping organic dyes. The nano-islands of dye in KDP were likely to be dissolved and enhance the non-linear optical properties of these materials.
文摘The most simple method for solventless synthesis of supramolecular complex of CMCR·2BPY·BZP, [CMCR = C-methylcalix[4]resorcinarene, BPY = 4,4'-bipyridine, BZP = benzophenone], is proposed. Although CMCR by itself is high melting point compound (above 300°C), CMCR was found to be dissolved in melt mixture of BPY and BZPeven below 120°C. In the mixture of the three components, the reaction occurs to form CMCR·2BPY·BZP supramolecular complex.
基金financially supported by the National Key R&D Program of China (Nos. 2018YFA0703200 and 2018YFA0208501)the National Natural Science Foundation of China (Nos. 22175185, 52003276, 52203247, 91963212 and 22002171)+1 种基金Beijing National Laboratory for Molecular Sciences (No. BNLMS-CXXM-202005)CAS-VPST Silk Road Science Fund 2022 (No. 121111KYSB20210006)
文摘Uniform and well-aligned organic semiconductor single crystals(OSSCs)are critical for high-performance electronic and optoelectronic device applications due to their long-range order and low defect density.However,it is still challenging to fabricate uniform and well-aligned OSSCs by an efficient and facile method.Here,we report a vapor-induced coating method to prepare uniform organic semiconductor stripe single crystals with well-aligned orientation.The coating velocity and solution concentration are important to control the stripe crystals’morphology,which influence the triple-phase contact line dewetting behavior and then change the mass transport of the meniscus.Insufficient solute supply causes the generation of dendritic crystals.Uniform stripe single crystals of high quality and pure orientation are prepared in the condition of a sufficient and suitable solute supply.Moreover,the electronic and optoelectronic properties are evaluated.Notably,the polarization-sensitive photodetectors based on the uniform stripe crystals exhibit high polarization sensitivity and its dichroic ratio of photocurrent is 1.98.This method is efficient for the preparation of various high-quality and uniform organic semiconductor stripe single crystals,opening an opportunity for high-performance organic functional devices.
基金supported by the National Natural Science Foundation of China(T2222004,92361301,62174102)。
文摘Multicomponent self-assembled chiral systems have attracted great attention due to their promising application in the area of spin-photonics and optoelectronics.In this work,through introducing an achiral third component into an achiral binary crystal,a chiral organic ternary crystal is fabricated,where both pronounced chiral-optical coupling and magnetic field dependence of chiral-optical activities are observed.The transformation of achiral structure into chiral structure generates a significant effect on the polarized state of light and the electron spin resonance signals.Moreover,the coupling between circularly polarized photon and spin is observed in chiral ternary crystal with pronounced chiral orbit,where obvious magnetic field-transmissivity loop is generated.Furthermore,temperature could increase the magnitude of lattice parameters to lead to a larger helix radius to increase the chiral orbit effect.Overall,this work indicates that the further exploration of photon-chiral orbit-spin interactions in organic chiral ternary crystals is promising.
文摘Process of crystal growth can be controlled by both surface kinetics and by volume transport as well.Although the complicated relation between the surface kinetics and volume transport exsits,generally,they are studied seprately.Due to the mathematical complexity of heat and mass transport equations,the in depth studies of heat and mass transport process become difficult.Most of the studies on the transport were performed for the growth from melt.Most of the work on Surface kinetics has been done for crystal growth from aqueous solution because the in situ observation of crystal growth is easily carried out.In recent years,the surface kinetics studies on the nanometer scale,even atomic scale,are demonstrated by using AFM.
基金We thank financial support from National Natural Science Foundation of China(52061135103 and 52173296)Structure characterizations were supported by Instrumental Analysis and Research Center of Sun Yat-sen University.
文摘The dilemma for the synthesis of covalent organic frameworks(COFs)is crystallinity and stability.Herein,we present the synthesis of a single-crystalline amide-linked COF,and demonstrate its excellent chemical as well as thermal stabilities.This study will inspire the synthesis of a wide spectrum of highly crystalline and stable COFs,promote their structure-property investigations and boost their applications in selective gas adsorption,storage and separation.
基金Project supported by the National Natural Science Foundation of China (Grant No 10604038)the Program for New Century Excellent Talents in University (NCET-2007)
文摘This paper reports that a charge-transfer salt dibutylammonium bis-7,7,8,8-tetraeyanoquinodimethane [DBA (TCNQ)2] has been prepared. The temperature dependences of the DC electrical conductivity of the DBA (TCNQ)2 single crystal measured along the crystallographic a, b, and c axes are reported. The crystal shows semicondueting behaviour and the room-temperature conductivities are highly anisotropic (σa = 3.63× 10^-4S/cm, σb = 2.84× 10^-6S/cm, and (σe = 1.82 × 10^-5S/cm). Particularly, a sharp semiconductor to semiconductor transition has been observed around 270 K on the resistivity curves measured under cooling and heating. In addition, thermal hysteresis phenomena on conductivity and differential scanning calorimetry curves are also reported.
基金supported by the 973 Program(No.2014CB643503)National Natural Science Foundation of China(Nos.51373150,51461165301)Zhejiang Province Natural Science Foundation(No.LZ13E030002)
文摘Organic field-effect transistors are of great importance to electronic devices.With the emergence of various preparation techniques for organic semiconductor materials,the device performance has been improved remarkably.Among all of the organic materials,single crystals are potentially promising for high performances due to high purity and well-ordered molecular arrangement.Based on organic single crystals,alignment and patterning techniques are essential for practical industrial application of electronic devices.In this review,recently developed methods for crystal alignment and patterning are described.
基金the National Natural Science Foundation of China(Nos.51672180,51622306,and 21673151)Natural Science Foundation of Jiangsu Province of China(No.BK20180845)Qing Lan Project,111 project,and the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).The authors thank the Collaborative Innovation Center of Suzhou Nano Science and Technology,Soochow University and Beamline BL14B1(Shanghai Synchrotron Radiation Facility)for providing beam time.
文摘Growth of two-dimensional(2D)organic single crystals(2DOSCs)on water surface has attracted increasing attention,because it can serve as a molecularly flat and defect-free substrate.However,large-area growth of 2DOSCs with controllable crystal orientation on water surface remains a key challenge.Herein,we develop a simple method,i.e.external-force-driven solution epitaxy(EFDSE),for the large-area growth of 2DOSCs at air/water interface.Using 2,7-didecylbenzothienobenzothiophene(C1o-BTBT)as an example,high-quality 2D C10-BTBT crystals on centimeter scale are generated by directionally controlling the spreading of organic solution on water surface with external force.Benefiting from the controllable crystal orientation with optimal charge transport,the corresponding 2DOSC-based organic field-effect transistors(OFETs)exhibit a high carrier mobility of 13.5 cm^2·V^-1·s^-1(effective mobility=5.4 cm^2·V^-1·s^-1 according to a reliability factor of 40%),which represents the best result achieved for water-surface-assembled 2DOSC based OFETs.Furthermore,by transterring the C1o-BTBT 2DOSCs to flexible substrates,devices with excellent bending stability are achieved.It is anticipated that our method will provide new insight into the controllable growth of large-area 2DOSCs for high-performance organic devices.
文摘Polyacrylate-based conductive coatings were prepared from polyacrylate emulsion as matrix and carbon black (CB) whose surface was treated with titanate coupling agent as conducting particles.One kind of organic crystal was added to study its effects on the electrical conductivity and PTC(positive temperature coefficient)effect of the conductive coatings.Experimental results show that the coatings containing only polyacrylate emulsion and CB exhibit an excellent electrical conductivity but bad PTC effect,and when organic crystal is added,PTC effect is characterized and can increase by 2 orders of magtitude.The critical transformation temperature of polyacrylate emulsion/CB PTC composites is decided by melting point of organic crystals.