Polyimide(PI)is widely used in high-frequency communication technology due to its exceptional comprehensive properties.However,traditional PI has a relatively elevated dielectric constant and dielectric loss.Herein,th...Polyimide(PI)is widely used in high-frequency communication technology due to its exceptional comprehensive properties.However,traditional PI has a relatively elevated dielectric constant and dielectric loss.Herein,the different cross-linked structures were introduced in PI matrix and conducted a detailed discussion on the influence of cross-linking agent content and cross-linking structure type on the overall performance of PI films.In comparison to the dielectric constant of 2.9 of neat PI,PI with an interchain cross-linking structure containing 2 wt%1,3,5-tris(4-aminophenyl)benzene(TAPB)(interchain-PI-2)exhibited the reduced dielectric constant of 2.55 at 1 MHz.The PI films with intrachain crosslinking structure containing 2 wt%TAPB(intrachain-PI-2)exhibited the lowest dielectric constant of 2.35 and the minimum dielectric loss of0.0075 at 1 MHz.It was due to the more entanglement junctions of intrachain-PI resulting in decreased carrier transport.The thermal expansion coefficients of both interchain-PI and intrachain-PI films were effectively reduced.Moreover,in contrast to interchain-PI films,the intrachain-PI films maintained colorlessness and transparency as the cross-linking agent content increased.This work compared the effects of two different cross-linked structures on the performance of PI films and provided a feasible way to obtain low-k PI films with excellent comprehensive performance for 5G applications.展开更多
Bulk heterojunction(BHJ)composites show improved power conversion efficiencies when optimized in terms of morphology using various film processing methods.A reduced carrier recombination loss in an optimized BHJ was c...Bulk heterojunction(BHJ)composites show improved power conversion efficiencies when optimized in terms of morphology using various film processing methods.A reduced carrier recombination loss in an optimized BHJ was characterized previously.However,the driving force that leads to this reduction was not clearly understood.In this study,we focus on the decreased carrier recombination loss and its driving force in optimized nonfullerene acceptor-based PTB7-Th:IEICO-4F BHJ composites.We demonstrate that the optimized BHJ shows deactivation in the sub-nanosecond nongeminate carrier recombination process.The driving force for this deactivation was determined to be the improved interchain hole delocalization between the polymers.An enhanced interchain hole delocalization was observed using steady-state photoinduced absorption(PIA)spectroscopy.In particular,increased splitting between the polaron PIA bands was noted.Moreover,improved interchain hole delocalization was observed for other state-of-the-art BHJ materials,including D18:Y6 with optimized morphologies.展开更多
Weak intermolecular interactions are of great significance in both the magnetostructural correlations and feasible applications of low-dimensional magnetic materials.However,it is greatly challenging to construct desi...Weak intermolecular interactions are of great significance in both the magnetostructural correlations and feasible applications of low-dimensional magnetic materials.However,it is greatly challenging to construct desirable chains with only different interchain aggregations due to the complexity and hard-tocontrol nature of intermolecular forces and the currently limited number of high-quality magnetic mediators.展开更多
Bistable mixed valence compounds have thermodynamically accessible phases at certain temperatures,and the electron transfer switches the electronic configurations by applying external stimuli like heat and light.Therm...Bistable mixed valence compounds have thermodynamically accessible phases at certain temperatures,and the electron transfer switches the electronic configurations by applying external stimuli like heat and light.Thermally induced phase transition temperatures range widely,while the photo-induced state conversions need irradiation at very low temperatures,such as below 30 K,and the photo-induced metastable state relaxes rapidly at low temperatures.We prepared new mixed-valence compounds of[Fe(bipy)(CN)_(4)]_(2)[CoL_(2)](L=4-[(1E)-2-phenyldiazenyl]pyridine for 1-papy and 4-(2-phenylethynyl)pyridine for 1-pepy)in which cyanide-bridged squared cores form corner-shared chains with substantial interchain π-π contacts.Mössbauser spectra revealed that 1-papy and 1-pepy are in the high-spin(HS)state[(Fe_(LS)^(Ⅲ))_(2)Co_(HS)^(Ⅱ)]at 300 K and the low-spin(LS)state[Fe_(LS)^(Ⅱ)Fe_(LS)^(Ⅲ)Co_(LS)^(Ⅲ)]at 78 K,confirming the occurrence of the electron transfer coupled spin transition(ETCST).Magnetic susceptibility measurements suggested their Tc values of 231 and 260 K,respectively.Photoirradiation(808 nm)for 1-papy and 1-pepy at 10 K induced the state conversion from the[LS]to the[HS^(*)]state,and the metastable[HS]^(*)state relaxed to the thermodynamically stable[LS]states at temperatures(Trelax)of 130 and 90 K,respectively.Furthermore,the[LS]states in 1-papy and 1-pepy were fully converted to the[HS^(*)]states by light irradiation at 78 and 50 K,respectively.The X-ray structural analyses showed characteristic coordination bond lengths for the metal ions in each electronic state before and after light irradiation,but shortened intrachain π_(L)⋯π_(L) contact distances,from 3.726(4)to 3.688(4)Å,were observed for 1-papy upon the state conversion from the[LS]to the[HS^(*)]state,despite the swollen cell volumes from 2479 to 2566Å^(3),respectively.Photomagneto and structural studies suggest that the intermolecular interactions increase the light-induced state conversion and relaxation temperatures.展开更多
Polaron dynamics in a system of highly ordered conjugated polymer chains is investigated based on the tight binding model.With the interchain coupling enhancing,it takes longer time for the electron added to the syste...Polaron dynamics in a system of highly ordered conjugated polymer chains is investigated based on the tight binding model.With the interchain coupling enhancing,it takes longer time for the electron added to the system to induce a localized polaron state.Beyond a certain strength of the interchain coupling,the electron evolves into a two-dimensional delocalized polaron state.Dynamical simulations suggest that the well-ordered organic molecule systems with two-dimensional polarons exhibit higher mobilities than the systems with intrachain localized polarons,as also suggested by earlier experiments.展开更多
We propose a novel approach to generate and manipulate topological Floquet bound states in the continuum(BICs)via a class of systems constructed by coupling two identical periodically driven one-dimensional Su-Schrief...We propose a novel approach to generate and manipulate topological Floquet bound states in the continuum(BICs)via a class of systems constructed by coupling two identical periodically driven one-dimensional Su-Schrieffer-Heeger chains.The formation of topological Floquet BICs can be adjusted only by tuning the driving amplitude or frequency,regardless of whether the static system has BICs or not.The interchain bias can only change the localization property of topological Floquet BICs,and a bigger bias can lead to transforming topological Floquet BICs into bound states out of the continuum(BOCs).But it does not change the topological properties of these topological Floquet states.Based on the repulsion effect of edge states,we propose to detect occurrence of topological Floquet BICs and transition point between topological Floquet BICs and BOCs using quantum walk.Our work provided a convenient and realistic approach for the experimental realization and manipulation of BICs in a single-particle quantum system.展开更多
The photoluminescence(PL) properties of poly[ (2, 5 - diphenylene - 1, 3, 4 - oxadiazole) - 4, 4’ - viny-lene] (O - PPV) are investigated using absorption and excitation measurements for different concentration ratio...The photoluminescence(PL) properties of poly[ (2, 5 - diphenylene - 1, 3, 4 - oxadiazole) - 4, 4’ - viny-lene] (O - PPV) are investigated using absorption and excitation measurements for different concentration ratios of solid-state O - PPV/ PEO (polyethylene oxide ) blends, as well as by comparing PL spectra for dilute solution and solid state pristine O - PPV. The solid film of O - PPV/PEO is prepared to investigate the interaction between polymers. The O - PPV molecules are dispersed into PEO which is used as a inert material in order to change the interaction between O - PPV. In the O -PPV/PEO blends, it is found that the PL spectra excited by 300nm for different concentration ratios are different. There are three peaks in the PL spectra of 1: 100 and 1: 200 (O - PPV/PEO) blends, and the relative intensities of peaks at 500nm and 460nm gradually decrease with lowering the concentrations of O - PPV. There leaves one peak at 416nm when the ratio of O - PPV to PEO is below 1: 300, and PL shape does not change any longer. The results show that the solid-state O - PPV emission arises from interchain charge-transfer states due to interchain effects.According to the absorption and photoluminescence spectra of the solid films, it is also believed that there are types of localized and delocalized states in conjugated polymers. The two types of states have different effects on charge-transfer state in different concentrations of solid films.展开更多
Type Ⅰ Ⅲ and Ⅴ collagens were extracted from bovine dermis and cornea by using pepsin treatment in acetic acid solution, followed by salt precipitation and dialysis, to purify and isolate each type of collagens. Th...Type Ⅰ Ⅲ and Ⅴ collagens were extracted from bovine dermis and cornea by using pepsin treatment in acetic acid solution, followed by salt precipitation and dialysis, to purify and isolate each type of collagens. The preparation process was analyzed by using sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE）. A reducing agent, 2-mercaptoethanol, was used to remove disulfide bonds and analyze the structure of the bonds involved between α chains in some types of collagens. The use of delayed reducing methods resulted in the difference between α1 （Ⅲ） and α1 （ Ⅰ ） chains in a mixture containing type Ⅰ and Ⅲ collagens. The structure of disulfide bonds among α chains exists potentially in type V collagen prepared from the pepsin-treatment extraction at 4 ℃, which differs from type Ⅲ collagen in relation to the locations of disulfide bonds. Compared with pepsin-treated collagen at 4 ℃, the relative molecular weights of α1 （V） and α2 （V） chains treated at room temperature decrease by 4.6% and 6.0%, respectively. It is concluded that type Ⅰ Ⅲ and Ⅴ collagens can be prepared from bovine dermis and cornea by the use of pepsin treatment, salt precipitation and dialysis. The interchain disulfide bonds lie potentially near the edges of termini of type V collagen molecules in extracellular matrix, and a small number of interchain crosslinks exist in type V collagen.展开更多
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
We investigate the metal-insulator transition in quasi-one-dimensional organic crystals of tetrathiotetracene-iodide, TTT2I3, in the 2D model. A crystal physical model is applied which takes into account two the most ...We investigate the metal-insulator transition in quasi-one-dimensional organic crystals of tetrathiotetracene-iodide, TTT2I3, in the 2D model. A crystal physical model is applied which takes into account two the most important hole-phonon interaction mechanisms. One is similar to that of deformation potential and the other is of polaron type. The scattering on defects is also considered and it is crucial for the explanation of the transition. The phonon polarization operator and the renormalized phonon spectrum are calculated in the random phase approximation for different temperatures applying the method of Green functions. We show that the transition is of Peierls type. The effect of lattice distortion on the dispersion of renormalized acoustic phonons is analyzed.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52103029)。
文摘Polyimide(PI)is widely used in high-frequency communication technology due to its exceptional comprehensive properties.However,traditional PI has a relatively elevated dielectric constant and dielectric loss.Herein,the different cross-linked structures were introduced in PI matrix and conducted a detailed discussion on the influence of cross-linking agent content and cross-linking structure type on the overall performance of PI films.In comparison to the dielectric constant of 2.9 of neat PI,PI with an interchain cross-linking structure containing 2 wt%1,3,5-tris(4-aminophenyl)benzene(TAPB)(interchain-PI-2)exhibited the reduced dielectric constant of 2.55 at 1 MHz.The PI films with intrachain crosslinking structure containing 2 wt%TAPB(intrachain-PI-2)exhibited the lowest dielectric constant of 2.35 and the minimum dielectric loss of0.0075 at 1 MHz.It was due to the more entanglement junctions of intrachain-PI resulting in decreased carrier transport.The thermal expansion coefficients of both interchain-PI and intrachain-PI films were effectively reduced.Moreover,in contrast to interchain-PI films,the intrachain-PI films maintained colorlessness and transparency as the cross-linking agent content increased.This work compared the effects of two different cross-linked structures on the performance of PI films and provided a feasible way to obtain low-k PI films with excellent comprehensive performance for 5G applications.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korea government(MSIT)(2022R1F1A1065586,2019R1A6A1A11053838)the GIST Research Institute(GRI)APRI grant funded by the GIST in 2022.
文摘Bulk heterojunction(BHJ)composites show improved power conversion efficiencies when optimized in terms of morphology using various film processing methods.A reduced carrier recombination loss in an optimized BHJ was characterized previously.However,the driving force that leads to this reduction was not clearly understood.In this study,we focus on the decreased carrier recombination loss and its driving force in optimized nonfullerene acceptor-based PTB7-Th:IEICO-4F BHJ composites.We demonstrate that the optimized BHJ shows deactivation in the sub-nanosecond nongeminate carrier recombination process.The driving force for this deactivation was determined to be the improved interchain hole delocalization between the polymers.An enhanced interchain hole delocalization was observed using steady-state photoinduced absorption(PIA)spectroscopy.In particular,increased splitting between the polaron PIA bands was noted.Moreover,improved interchain hole delocalization was observed for other state-of-the-art BHJ materials,including D18:Y6 with optimized morphologies.
基金support from the NSFC(Grants 21671149,21571140,and 21531005)the Program for Innovative Research Team in University of Tianjin(TD13-5074)are gratefully acknowledged。
文摘Weak intermolecular interactions are of great significance in both the magnetostructural correlations and feasible applications of low-dimensional magnetic materials.However,it is greatly challenging to construct desirable chains with only different interchain aggregations due to the complexity and hard-tocontrol nature of intermolecular forces and the currently limited number of high-quality magnetic mediators.
基金supported by the National Natural Science Foundation of China(Grants,22025101,22222103,22173015,21871039,91961114,22071017,22103009 and 22203013)the Fundamental Research Funds for the Central Universities,China(DUT22LAB606).
文摘Bistable mixed valence compounds have thermodynamically accessible phases at certain temperatures,and the electron transfer switches the electronic configurations by applying external stimuli like heat and light.Thermally induced phase transition temperatures range widely,while the photo-induced state conversions need irradiation at very low temperatures,such as below 30 K,and the photo-induced metastable state relaxes rapidly at low temperatures.We prepared new mixed-valence compounds of[Fe(bipy)(CN)_(4)]_(2)[CoL_(2)](L=4-[(1E)-2-phenyldiazenyl]pyridine for 1-papy and 4-(2-phenylethynyl)pyridine for 1-pepy)in which cyanide-bridged squared cores form corner-shared chains with substantial interchain π-π contacts.Mössbauser spectra revealed that 1-papy and 1-pepy are in the high-spin(HS)state[(Fe_(LS)^(Ⅲ))_(2)Co_(HS)^(Ⅱ)]at 300 K and the low-spin(LS)state[Fe_(LS)^(Ⅱ)Fe_(LS)^(Ⅲ)Co_(LS)^(Ⅲ)]at 78 K,confirming the occurrence of the electron transfer coupled spin transition(ETCST).Magnetic susceptibility measurements suggested their Tc values of 231 and 260 K,respectively.Photoirradiation(808 nm)for 1-papy and 1-pepy at 10 K induced the state conversion from the[LS]to the[HS^(*)]state,and the metastable[HS]^(*)state relaxed to the thermodynamically stable[LS]states at temperatures(Trelax)of 130 and 90 K,respectively.Furthermore,the[LS]states in 1-papy and 1-pepy were fully converted to the[HS^(*)]states by light irradiation at 78 and 50 K,respectively.The X-ray structural analyses showed characteristic coordination bond lengths for the metal ions in each electronic state before and after light irradiation,but shortened intrachain π_(L)⋯π_(L) contact distances,from 3.726(4)to 3.688(4)Å,were observed for 1-papy upon the state conversion from the[LS]to the[HS^(*)]state,despite the swollen cell volumes from 2479 to 2566Å^(3),respectively.Photomagneto and structural studies suggest that the intermolecular interactions increase the light-induced state conversion and relaxation temperatures.
文摘Polaron dynamics in a system of highly ordered conjugated polymer chains is investigated based on the tight binding model.With the interchain coupling enhancing,it takes longer time for the electron added to the system to induce a localized polaron state.Beyond a certain strength of the interchain coupling,the electron evolves into a two-dimensional delocalized polaron state.Dynamical simulations suggest that the well-ordered organic molecule systems with two-dimensional polarons exhibit higher mobilities than the systems with intrachain localized polarons,as also suggested by earlier experiments.
基金supported by the National Natural Science Foundation of China(Grant Nos.12175315 and 12205385)。
文摘We propose a novel approach to generate and manipulate topological Floquet bound states in the continuum(BICs)via a class of systems constructed by coupling two identical periodically driven one-dimensional Su-Schrieffer-Heeger chains.The formation of topological Floquet BICs can be adjusted only by tuning the driving amplitude or frequency,regardless of whether the static system has BICs or not.The interchain bias can only change the localization property of topological Floquet BICs,and a bigger bias can lead to transforming topological Floquet BICs into bound states out of the continuum(BOCs).But it does not change the topological properties of these topological Floquet states.Based on the repulsion effect of edge states,we propose to detect occurrence of topological Floquet BICs and transition point between topological Floquet BICs and BOCs using quantum walk.Our work provided a convenient and realistic approach for the experimental realization and manipulation of BICs in a single-particle quantum system.
文摘The photoluminescence(PL) properties of poly[ (2, 5 - diphenylene - 1, 3, 4 - oxadiazole) - 4, 4’ - viny-lene] (O - PPV) are investigated using absorption and excitation measurements for different concentration ratios of solid-state O - PPV/ PEO (polyethylene oxide ) blends, as well as by comparing PL spectra for dilute solution and solid state pristine O - PPV. The solid film of O - PPV/PEO is prepared to investigate the interaction between polymers. The O - PPV molecules are dispersed into PEO which is used as a inert material in order to change the interaction between O - PPV. In the O -PPV/PEO blends, it is found that the PL spectra excited by 300nm for different concentration ratios are different. There are three peaks in the PL spectra of 1: 100 and 1: 200 (O - PPV/PEO) blends, and the relative intensities of peaks at 500nm and 460nm gradually decrease with lowering the concentrations of O - PPV. There leaves one peak at 416nm when the ratio of O - PPV to PEO is below 1: 300, and PL shape does not change any longer. The results show that the solid-state O - PPV emission arises from interchain charge-transfer states due to interchain effects.According to the absorption and photoluminescence spectra of the solid films, it is also believed that there are types of localized and delocalized states in conjugated polymers. The two types of states have different effects on charge-transfer state in different concentrations of solid films.
基金Supported by National Natural Science Foundation of China (No.30970724)Natural Science Foundation of Tianjin (No.08JCYBJC03400)
文摘Type Ⅰ Ⅲ and Ⅴ collagens were extracted from bovine dermis and cornea by using pepsin treatment in acetic acid solution, followed by salt precipitation and dialysis, to purify and isolate each type of collagens. The preparation process was analyzed by using sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE）. A reducing agent, 2-mercaptoethanol, was used to remove disulfide bonds and analyze the structure of the bonds involved between α chains in some types of collagens. The use of delayed reducing methods resulted in the difference between α1 （Ⅲ） and α1 （ Ⅰ ） chains in a mixture containing type Ⅰ and Ⅲ collagens. The structure of disulfide bonds among α chains exists potentially in type V collagen prepared from the pepsin-treatment extraction at 4 ℃, which differs from type Ⅲ collagen in relation to the locations of disulfide bonds. Compared with pepsin-treated collagen at 4 ℃, the relative molecular weights of α1 （V） and α2 （V） chains treated at room temperature decrease by 4.6% and 6.0%, respectively. It is concluded that type Ⅰ Ⅲ and Ⅴ collagens can be prepared from bovine dermis and cornea by the use of pepsin treatment, salt precipitation and dialysis. The interchain disulfide bonds lie potentially near the edges of termini of type V collagen molecules in extracellular matrix, and a small number of interchain crosslinks exist in type V collagen.
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We investigate the metal-insulator transition in quasi-one-dimensional organic crystals of tetrathiotetracene-iodide, TTT2I3, in the 2D model. A crystal physical model is applied which takes into account two the most important hole-phonon interaction mechanisms. One is similar to that of deformation potential and the other is of polaron type. The scattering on defects is also considered and it is crucial for the explanation of the transition. The phonon polarization operator and the renormalized phonon spectrum are calculated in the random phase approximation for different temperatures applying the method of Green functions. We show that the transition is of Peierls type. The effect of lattice distortion on the dispersion of renormalized acoustic phonons is analyzed.
