Halide perovskites show excellent optoelectronic properties for solar cell application.Notably,perovskite crystalline structures have been widely re-ported to deliver superior ferroelectric properties.As a result,the ...Halide perovskites show excellent optoelectronic properties for solar cell application.Notably,perovskite crystalline structures have been widely re-ported to deliver superior ferroelectric properties.As a result,the integration of the ferroelectric process with the photon‐to‐electron energy conversion process becomes feasible to generate interesting photo‐physical properties and further boost the device performance of perovskite solar cells(PSCs),which have started to attract more and more attention in recent years.Here,we have reviewed the recent progress in PSCs with ferroelectricity(FE‐PSCs),by classifying them into three regimes according to the degree of phase segre-gation,for example,the layer‐structured ferroelectric/halide perovskite com-posite,micro phase‐separated ferroelectric/halide perovskite composite,and the intrinsic ferroelectric halide perovskite composite.The different composite structures enable a large range of interesting optoelectronic properties and the specific structure significantly enhances the device performance of PSCs.The most prominent contribution of ferroelectricity is that it can provide an extra electrical field to drive charge generation,transport,and collection.Further,key challenges and opportunities of the integration of ferroelectricity with photo-voltaics are discussed.We hope our work can draw intensive attention in this field to accelerate the establishment of the basic theories in ferroelectricity and the commercialization of PSCs.展开更多
Presents information on a study which analyzed superapproximation properties for the interpolation operator of projection type on two-dimensional domain. Discussion on the interpolation operator of projection type and...Presents information on a study which analyzed superapproximation properties for the interpolation operator of projection type on two-dimensional domain. Discussion on the interpolation operator of projection type and its superapproximation properties; Superconvergence of Ritz projection; Proof and applications of the superconveregence of Ritz-Volterra projection.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
Optic-electric responsive materials have attracted much attention for their applications in temperaturesensing,actuators,and memory switches.However,it is a challenge to integrate various functions to form multifuncti...Optic-electric responsive materials have attracted much attention for their applications in temperaturesensing,actuators,and memory switches.However,it is a challenge to integrate various functions to form multifunctional responsive materials.As molecule-based hybrid materials usually consist of organic and inorganic components,the introduction of multiple functions can be achieved through structural construction.Thus far,even though fulltemperature cover is required for device applications,fulltemperature covered multi-switchable hybrid materials have rarely been successfully synthesized.Herein,the dynamic[(CH3)3NOH]+cation and luminous center Mn(II)were introduced to form a hybrid material[(CH3)3NOH][Mn Cl3],showing multiple temperature-responsive behaviors.Upon temperature change,it exhibits multi-state dielectric switching response and intensity or peak shift response of luminous in full-temperature range(low,room,and high temperatures).These responsive behaviors are triggered by the motion or reorientation of[(CH3)3NOH]+cations and inorganic framework.Overall,the switchable photoelectric material has potential applications in multiple encrypted storage and sensor devices.展开更多
Material stability is always the key factor for applied materials especially the working environment that requires higher temperature sensitivity or temperature fluctuation range.In which,the stimulus-response perovsk...Material stability is always the key factor for applied materials especially the working environment that requires higher temperature sensitivity or temperature fluctuation range.In which,the stimulus-response perovskite materials are just sensitive to stability to ensure the accuracy and stability of the signals,in the applied devices of batteries and memory storage devices and so on.However,it is still a tremendous challenge to improve the stability of perovskite materials,and maintain reliability in the devices.Here,a novel ABX_(2)X'_(1)(X-site doping in an ABX_(3))compound[CEMP]-[CdBr_(2)(SCN)](1,CEMP=1-(2-chloro-ethyl)-1-methyl-piperidine)with remarkable high-temperature reversible dielectric switching behavior was proposed.The strategy of[SCN]^(−)doping in perovskite for improving the stability was successfully achieved.Meanwhile,the steric hindrance is increased while the energy barrier is also increased by replacing hydrogen with flexible groups,which leads to a high-temperature reversible phase transition.The new finding provides a new direction to enrich new applications and design ideas of perovskite materials.Especially the X-site strategy of doping or substitution in the ABX_(3),it will promote ingenious and perfect experimental results in material synthesis and performance improvement by chemistry disciplines.展开更多
In this paper we are concerned with the pricing of lookback options with American type constrains. Based on the differential linear complementary formula associated with the pricing problem, an implicit difference sch...In this paper we are concerned with the pricing of lookback options with American type constrains. Based on the differential linear complementary formula associated with the pricing problem, an implicit difference scheme is constructed and analyzed. We show that there exists a unique difference solution which is unconditionally stable. Using the notion of viscosity solutions, we also prove that the finite difference solution converges uniformly to the viscosity solution of the continuous problem. Furthermore, by means of the variational inequality analysis method, the O（△t ＋ △x^2）-order error estimate is derived in the discrete L2-norm provided that the continuous problem is sufficiently regular. In addition, a numerical example is provided to illustrate the theoretical results.展开更多
Two-dimensional(2D)organic-inorganic hybrid perovskites(OIHPs)have attracted phenomenal attention because of their superior optoelectronic performances.The combination of their structural tunability and material stabi...Two-dimensional(2D)organic-inorganic hybrid perovskites(OIHPs)have attracted phenomenal attention because of their superior optoelectronic performances.The combination of their structural tunability and material stability offers an unprecedented opportunity to engineer materials with unique functionalities.However,developing a rapid and effective design method for introducing luminescence into dielectric switch and realizing controllable regulation has been an enormous challenge.Thus far,materials with tunable optoelectronic multichannel response have not been successfully implemented.In this study,we successfully developed a facile and effective mechanochemical method for realizing the integration and regulation of luminescence and dielectric switch in 2D perovskites,which is unprecedented for the design of dielectric switching materials.The mild external mechanical stimuli enabled the formation of Mn ion-doped 2D hybrid perovskites(Cyclopropylammonium)2Pb1-xMnxBr4 with excellent dielectric switch and rapidly controllable luminescence of highly efficient blue light,white light,pink light,and orange light.This work will provide a new perspective on the rapid and effective design of multifunctional materials and can inspire the future development of low-cost and high-efficiency electronics.展开更多
The preconditioner for parameterized inexact Uzawa methods have been used to solve some indefinite saddle point problems. Firstly, we modify the preconditioner by making it more generalized, then we use theoretical an...The preconditioner for parameterized inexact Uzawa methods have been used to solve some indefinite saddle point problems. Firstly, we modify the preconditioner by making it more generalized, then we use theoretical analyses to show that the iteration method converges under certain conditions. Moreover, we discuss the optimal parameter and matrices based on these conditions. Finally, we propose two improved methods. Numerical experiments are provided to show the effectiveness of the modified preconditioner. All methods have fantastic convergence rates by choosing the optimal parameter and matrices.展开更多
We study the enhancement of accuracy,by means of the convolution postprocessing technique,for discontinuous Galerkin(DG)approximations to hyperbolic problems.Previous investigations have focused on the superconvergenc...We study the enhancement of accuracy,by means of the convolution postprocessing technique,for discontinuous Galerkin(DG)approximations to hyperbolic problems.Previous investigations have focused on the superconvergence obtained by this technique for elliptic,time-dependent hyperbolic and convection-diffusion problems.In this paper,we demonstrate that it is possible to extend this postprocessing technique to the hyperbolic problems written as the Friedrichs’systems by using an upwind-like DG method.We prove that the L2-error of the DG solution is of order k+1/2,and further the post-processed DG solution is of order 2k+1 if Qkpolynomials are used.The key element of our analysis is to derive the(2k+1)-order negative norm error estimate.Numerical experiments are provided to illustrate the theoretical analysis.展开更多
In this paper, we investigate the a priori and a posteriori error estimates for the discontinuous Galerkin finite element approximation to a regularization version of the variational inequality of the second kind. We ...In this paper, we investigate the a priori and a posteriori error estimates for the discontinuous Galerkin finite element approximation to a regularization version of the variational inequality of the second kind. We show the optimal error estimates in the DG-norm （stronger than the H1 norm） and the L2 norm, respectively. Furthermore, some residual-based a posteriori error estimators are established which provide global upper bounds and local lower bounds on the discretization error. These a posteriori analysis results can be applied to develop the adaptive DG methods.展开更多
As the traditional cross-coupling control method cannot meet the requirements for tracking accuracy and contour control accuracy in large curvature positions, an integrated control strategy of cross-coupling contour e...As the traditional cross-coupling control method cannot meet the requirements for tracking accuracy and contour control accuracy in large curvature positions, an integrated control strategy of cross-coupling contour error compensation based on chord error constraint, which consists of a cross-coupling controller and an improved position error compensator, is proposed. To reduce the contour error, a PI-type cross-coupling controller is designed, with its stability being analyzed by using the contour error transfer function. Moreover, a feed rate regulator based on the chord error constraint is proposed, which performs speed planning with the maximum feed rate allowed by the large curvature position as the constraint condition, so as to meet the requirements of large curvature positions for the chord error. Besides, an improved position error compensation method is further presented by combining the feed rate regulator with the position error compensator, which improves the tracking accuracy via the advance compensation of tracking error. The biaxial experimental results of non-uniform rational B-splines curves indicate that the proposed integrated control strategy can significantly improve the tracking and contour control accuracy in biaxial contour following tasks.展开更多
In this paper, a non-smooth population model with impulsive effects is proposed by combining discontinuity and non-smoothness. According to the qualitative theory of differential equations, the global analysis of the ...In this paper, a non-smooth population model with impulsive effects is proposed by combining discontinuity and non-smoothness. According to the qualitative theory of differential equations, the global analysis of the model is discussed. Using the theory of impulsive differential equations, the existence conditions of order one periodic solution are obtained. And the impulsive controllers are designed to make the pest populations stay at the refuge level. Some simulations are carried out to prove the results.展开更多
Presents a study that applied a general error analysis framework for the finite volume element (FVE) approximation to the Ritz-Volterra projection, the Sobolev equations and parabolic integro-differential equations. F...Presents a study that applied a general error analysis framework for the finite volume element (FVE) approximation to the Ritz-Volterra projection, the Sobolev equations and parabolic integro-differential equations. Formulation of the FVE methods in linear finite element spaces defined on a triangulation; Information on the L[sub2] and H1 norm error estimates; Approximations to Sobolev equations and parabolic integro-differential equations.展开更多
基金Innovation and Global EngagementFaculty of Mathematical&Physical Science+11 种基金Research start‐up fund from Zhejiang UniversityChinese Scholarship CouncilUniversity of Sydney‐University College London Partnership Collaboration AwardsNational Key Research and Development Program of China,Grant/Award Number:2022YFB4200600Accelerating CCS Technologies,Horizon2020 Project,Grant/Award Number:691712China Postdoctoral Science Foundation’,Grant/Award Number:2023M743082University College London's ResearchNational Natural Science Foundation of China,Grant/Award Numbers:52127806,52173185NEXTCCUS,Grant/Award Number:327327Department for Energy Security and Net ZeroCornell‐UCL Global Strategic Collaboration AwardsCambridge Materials Limited。
文摘Halide perovskites show excellent optoelectronic properties for solar cell application.Notably,perovskite crystalline structures have been widely re-ported to deliver superior ferroelectric properties.As a result,the integration of the ferroelectric process with the photon‐to‐electron energy conversion process becomes feasible to generate interesting photo‐physical properties and further boost the device performance of perovskite solar cells(PSCs),which have started to attract more and more attention in recent years.Here,we have reviewed the recent progress in PSCs with ferroelectricity(FE‐PSCs),by classifying them into three regimes according to the degree of phase segre-gation,for example,the layer‐structured ferroelectric/halide perovskite com-posite,micro phase‐separated ferroelectric/halide perovskite composite,and the intrinsic ferroelectric halide perovskite composite.The different composite structures enable a large range of interesting optoelectronic properties and the specific structure significantly enhances the device performance of PSCs.The most prominent contribution of ferroelectricity is that it can provide an extra electrical field to drive charge generation,transport,and collection.Further,key challenges and opportunities of the integration of ferroelectricity with photo-voltaics are discussed.We hope our work can draw intensive attention in this field to accelerate the establishment of the basic theories in ferroelectricity and the commercialization of PSCs.
基金Supported by the Foundation of National Education Department for Key Teachers in Chinese University.
文摘Presents information on a study which analyzed superapproximation properties for the interpolation operator of projection type on two-dimensional domain. Discussion on the interpolation operator of projection type and its superapproximation properties; Superconvergence of Ritz projection; Proof and applications of the superconveregence of Ritz-Volterra projection.
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 National Natural Science Foundation of China(21991141)the Natural Science Foundation of Zhejiang Province(LZ20B010001)Zhejiang Normal University。
文摘Optic-electric responsive materials have attracted much attention for their applications in temperaturesensing,actuators,and memory switches.However,it is a challenge to integrate various functions to form multifunctional responsive materials.As molecule-based hybrid materials usually consist of organic and inorganic components,the introduction of multiple functions can be achieved through structural construction.Thus far,even though fulltemperature cover is required for device applications,fulltemperature covered multi-switchable hybrid materials have rarely been successfully synthesized.Herein,the dynamic[(CH3)3NOH]+cation and luminous center Mn(II)were introduced to form a hybrid material[(CH3)3NOH][Mn Cl3],showing multiple temperature-responsive behaviors.Upon temperature change,it exhibits multi-state dielectric switching response and intensity or peak shift response of luminous in full-temperature range(low,room,and high temperatures).These responsive behaviors are triggered by the motion or reorientation of[(CH3)3NOH]+cations and inorganic framework.Overall,the switchable photoelectric material has potential applications in multiple encrypted storage and sensor devices.
基金supported by the National Natural Science Foundation of China(No.21991141)Natural Science Foundation of Zhejiang Province(No.LZ20B010001)Zhejiang Normal University for financial support.
文摘Material stability is always the key factor for applied materials especially the working environment that requires higher temperature sensitivity or temperature fluctuation range.In which,the stimulus-response perovskite materials are just sensitive to stability to ensure the accuracy and stability of the signals,in the applied devices of batteries and memory storage devices and so on.However,it is still a tremendous challenge to improve the stability of perovskite materials,and maintain reliability in the devices.Here,a novel ABX_(2)X'_(1)(X-site doping in an ABX_(3))compound[CEMP]-[CdBr_(2)(SCN)](1,CEMP=1-(2-chloro-ethyl)-1-methyl-piperidine)with remarkable high-temperature reversible dielectric switching behavior was proposed.The strategy of[SCN]^(−)doping in perovskite for improving the stability was successfully achieved.Meanwhile,the steric hindrance is increased while the energy barrier is also increased by replacing hydrogen with flexible groups,which leads to a high-temperature reversible phase transition.The new finding provides a new direction to enrich new applications and design ideas of perovskite materials.Especially the X-site strategy of doping or substitution in the ABX_(3),it will promote ingenious and perfect experimental results in material synthesis and performance improvement by chemistry disciplines.
基金supported in part by the National Basic Research Program(2007CB814906)the National Natural Science Foundation of China(10771031,10471019,10471103,and 10771158)+1 种基金Social Science Foundation of the Ministry of Education of China(Numerical methods for convertible bonds,06JA630047)Tianjin Natural Science Foundation(07JCYBJC14300)and Tianjin University of Finance and Economics
文摘In this paper we are concerned with the pricing of lookback options with American type constrains. Based on the differential linear complementary formula associated with the pricing problem, an implicit difference scheme is constructed and analyzed. We show that there exists a unique difference solution which is unconditionally stable. Using the notion of viscosity solutions, we also prove that the finite difference solution converges uniformly to the viscosity solution of the continuous problem. Furthermore, by means of the variational inequality analysis method, the O（△t ＋ △x^2）-order error estimate is derived in the discrete L2-norm provided that the continuous problem is sufficiently regular. In addition, a numerical example is provided to illustrate the theoretical results.
基金the National Natural Science Foundation of China(21991141)the Natural Science Foundation of Zhejiang Province(LZ20B010001)Zhejiang Normal University。
文摘Two-dimensional(2D)organic-inorganic hybrid perovskites(OIHPs)have attracted phenomenal attention because of their superior optoelectronic performances.The combination of their structural tunability and material stability offers an unprecedented opportunity to engineer materials with unique functionalities.However,developing a rapid and effective design method for introducing luminescence into dielectric switch and realizing controllable regulation has been an enormous challenge.Thus far,materials with tunable optoelectronic multichannel response have not been successfully implemented.In this study,we successfully developed a facile and effective mechanochemical method for realizing the integration and regulation of luminescence and dielectric switch in 2D perovskites,which is unprecedented for the design of dielectric switching materials.The mild external mechanical stimuli enabled the formation of Mn ion-doped 2D hybrid perovskites(Cyclopropylammonium)2Pb1-xMnxBr4 with excellent dielectric switch and rapidly controllable luminescence of highly efficient blue light,white light,pink light,and orange light.This work will provide a new perspective on the rapid and effective design of multifunctional materials and can inspire the future development of low-cost and high-efficiency electronics.
文摘The preconditioner for parameterized inexact Uzawa methods have been used to solve some indefinite saddle point problems. Firstly, we modify the preconditioner by making it more generalized, then we use theoretical analyses to show that the iteration method converges under certain conditions. Moreover, we discuss the optimal parameter and matrices based on these conditions. Finally, we propose two improved methods. Numerical experiments are provided to show the effectiveness of the modified preconditioner. All methods have fantastic convergence rates by choosing the optimal parameter and matrices.
基金This work was supported by the State Key Laboratory of Synthetical Automation for Process Industries Fundamental Research Funds 2013ZCX02the National Natural Science Funds of China 11371081
文摘We study the enhancement of accuracy,by means of the convolution postprocessing technique,for discontinuous Galerkin(DG)approximations to hyperbolic problems.Previous investigations have focused on the superconvergence obtained by this technique for elliptic,time-dependent hyperbolic and convection-diffusion problems.In this paper,we demonstrate that it is possible to extend this postprocessing technique to the hyperbolic problems written as the Friedrichs’systems by using an upwind-like DG method.We prove that the L2-error of the DG solution is of order k+1/2,and further the post-processed DG solution is of order 2k+1 if Qkpolynomials are used.The key element of our analysis is to derive the(2k+1)-order negative norm error estimate.Numerical experiments are provided to illustrate the theoretical analysis.
基金Supported by the National Natural Science Foundation of China(No.11071033)
文摘In this paper, we investigate the a priori and a posteriori error estimates for the discontinuous Galerkin finite element approximation to a regularization version of the variational inequality of the second kind. We show the optimal error estimates in the DG-norm （stronger than the H1 norm） and the L2 norm, respectively. Furthermore, some residual-based a posteriori error estimators are established which provide global upper bounds and local lower bounds on the discretization error. These a posteriori analysis results can be applied to develop the adaptive DG methods.
基金This work is supported by the National Science and Technology Major Project of China(Grant No.2015ZX04005006)the Science and Technology Major Project of Zhongshan City,China(Grant Nos.2016F2FC0006 and 2018A10018).
文摘As the traditional cross-coupling control method cannot meet the requirements for tracking accuracy and contour control accuracy in large curvature positions, an integrated control strategy of cross-coupling contour error compensation based on chord error constraint, which consists of a cross-coupling controller and an improved position error compensator, is proposed. To reduce the contour error, a PI-type cross-coupling controller is designed, with its stability being analyzed by using the contour error transfer function. Moreover, a feed rate regulator based on the chord error constraint is proposed, which performs speed planning with the maximum feed rate allowed by the large curvature position as the constraint condition, so as to meet the requirements of large curvature positions for the chord error. Besides, an improved position error compensation method is further presented by combining the feed rate regulator with the position error compensator, which improves the tracking accuracy via the advance compensation of tracking error. The biaxial experimental results of non-uniform rational B-splines curves indicate that the proposed integrated control strategy can significantly improve the tracking and contour control accuracy in biaxial contour following tasks.
文摘In this paper, a non-smooth population model with impulsive effects is proposed by combining discontinuity and non-smoothness. According to the qualitative theory of differential equations, the global analysis of the model is discussed. Using the theory of impulsive differential equations, the existence conditions of order one periodic solution are obtained. And the impulsive controllers are designed to make the pest populations stay at the refuge level. Some simulations are carried out to prove the results.
文摘Presents a study that applied a general error analysis framework for the finite volume element (FVE) approximation to the Ritz-Volterra projection, the Sobolev equations and parabolic integro-differential equations. Formulation of the FVE methods in linear finite element spaces defined on a triangulation; Information on the L[sub2] and H1 norm error estimates; Approximations to Sobolev equations and parabolic integro-differential equations.
