The stable spectrum can be obtained when the voltage changes, which is a necessary condition for the white organic light emitting diode (WOLED) device to be widely used in the field of solid-state lighting. However, w...The stable spectrum can be obtained when the voltage changes, which is a necessary condition for the white organic light emitting diode (WOLED) device to be widely used in the field of solid-state lighting. However, with the increase of voltage, the movement of the recombination zone (RZ) is inevitable because the perfect bipolar host material is difficult to obtain, which will redistribute the energy in the light emitting layer (EML) and affect the stability of the spectrum. We fabricate a series of ternary hybrid WOLEDs with a simple structure by inserting ultra-thin PO-T2T into the blue exciplex (TCTA:TPBi) to form the green interface exciplex. Without considering the movement of RZ, device B2 realizes the dynamic balance energy distribution in EML and stable spectrum by controlling two processes of the Dexter energy transfer and exciton capture. By modifying the doping ratio of the host material, we also find that the broadened RZ is helpful to further improve the spectral stability of the device. When the voltage changes from 3 V to 7 V, the change range of color coordinates is only (0.026, 0.025).展开更多
Optimization and simplification of optical systems represent a milestone in advancing the development of handheld and portable laser-induced breakdown spectroscopy(LIBS)systems towards smaller,more integrated forms.Th...Optimization and simplification of optical systems represent a milestone in advancing the development of handheld and portable laser-induced breakdown spectroscopy(LIBS)systems towards smaller,more integrated forms.This research,for the first time,conducted a comprehensive optimization design and comparative analysis of three compact LIBS system optical paths:the paraxial optical path(OP),the off-axis OP,and the reflective OP.The differences in spectral intensity and stability among these paths were revealed,providing a scientific basis for selecting the optimal OP for LIBS systems.The research found that the paraxial OP excels in spectral performance and quantitative analysis accuracy,making it the preferred choice for compact LIBS systems.Specifically,the paraxial OP significantly enhances spectral intensity,achieving a 6 times improvement over the off-axis OP and an even more remarkable 150 times increase compared to the reflective OP,greatly enhancing detection sensitivity.Additionally,the relative standard deviation,spectral stability index,maintains a consistently low level,ranging from 10.9%to 13.4%,significantly outperforming the other two OPs and ensuring the reliability of analytical results.In the field of quantitative analysis,the paraxial OP also demonstrates higher accuracy,precision,and sensitivity,comparing to other OPs.The quantitative analysis models for Si,Cu,and Ti elements exhibit excellent fitting,providing users with high-quality quantitative analysis results that are of great significance for applications in material science,environmental monitoring,industrial inspection,and other fields.In summary,this study not only confirms the enormous application potential of the paraxial OP in compact LIBS systems but also provides valuable practical experience and theoretical support for the miniaturization and integration of LIBS systems.Looking ahead,with continuous technological advancements,the design of the paraxial OP is expected to further propel the widespread adoption of LIBS technology in portable,on-site detection applications.展开更多
A strain-compensated InGaN quantum well（QW） active region employing a tensile AlGaN barrier is analyzed.Its spectral stability and efficiency droop for a dual-blue light-emitting diode（LED） are improved compared w...A strain-compensated InGaN quantum well（QW） active region employing a tensile AlGaN barrier is analyzed.Its spectral stability and efficiency droop for a dual-blue light-emitting diode（LED） are improved compared with those of the conventional InGaN/GaN QW dual-blue LEDs based on a stacking structure of two In0.18Ga0.82N/GaN QWs and two In0.12Ga0.88N/GaN QWs on the same sapphire substrate.It is found that the optimal performance is achieved when the Al composition of the strain-compensated AlGaN layer is 0.12 in blue QW and 0.21 in blue-violet QW.The improvement performance can be attributed to the strain-compensated InGaN-AlGaN/GaN QW,which can provide a better carrier confinement and effectively reduce leakage current.展开更多
For a coupled slow-fast FitzHugh-Nagumo(FHN)equation derived from a reaction-diffusionmechanics(RDM)model,Holzer et al.(2013)studied the existence and stability of the travelling pulse,which consists of two fast orbit...For a coupled slow-fast FitzHugh-Nagumo(FHN)equation derived from a reaction-diffusionmechanics(RDM)model,Holzer et al.(2013)studied the existence and stability of the travelling pulse,which consists of two fast orbit arcs and two slow ones,where one fast segment passes the unique fold point with algebraic decreasing and two slow ones follow normally hyperbolic critical curve segments.Shen and Zhang(2021)obtained the existence of the travelling pulse,whose two fast orbit arcs both exponentially decrease,and one of the slow orbit arcs could be normally hyperbolic or not at the origin.Here,we characterize both the nonlinear and spectral stability of this travelling pulse.展开更多
The present paper deals with results of stability/instability of solitary waves with nonzero asymptotic value for a microstructure PDE. By the exact solitary wave solutions and detailed computations, we set up the exp...The present paper deals with results of stability/instability of solitary waves with nonzero asymptotic value for a microstructure PDE. By the exact solitary wave solutions and detailed computations, we set up the explicit expression for the discrimination d′′（c）. Finally, a complete study of orbital stablity/instablity for the explicit exact solutions is given.展开更多
Perovskite light-emitting diodes(PeLEDs)have emerged as a promising candidate for next-generation displays owing to their excellent luminescent properties and low cost.However,the development of deep blue PeLEDs has b...Perovskite light-emitting diodes(PeLEDs)have emerged as a promising candidate for next-generation displays owing to their excellent luminescent properties and low cost.However,the development of deep blue PeLEDs has been hindered compared to red and green emission devices,largely due to the challenge of an unstable spectrum.In this work,we present a method for achieving spectral stabilization by using the organic ligand dipotassium 7-hydroxynaphthalene-1,3-disulphonate(G SALT).Combined with experimental results,we confirmed that the multiple interactions between G SALT and perovskite components played an important role in rearranging phase distribution and enhancing spectral stability.The fabricated deep blue PeLEDs demonstrated electrolu-minescence(EL)peak at 456 nm with Commission Internationale de I’Eclairage(CIE)coordinates of(0.149,0.063),meeting well with the Rec.2020 standard.Meanwhile,the peak external quantum efficiency(EQE)of 2.5% accompanied by the maximum luminance(Lmax)of 969.7 cd/m^(2) was achieved.The T50 lifetime was prolonged to 10 min under a constant current density of 12 mA/cm^(2),and there was no significant spectral shift in the EL spectra at high driving voltages ranging from 3.5 to 6.5 V.Furthermore,the films demonstrated stable photoluminescence spectra when subjected to ultraviolet excitation at 365 nm and continuous heating at 65°C.This study confirms the active role of organic compound ligands in quasi-two-dimensional(quasi-2D)perovskites and provides a new approach for developing stable ligands for the luminescent layer of perovskites in the future.展开更多
Low efficiency and spectral instability caused by the surface defects have been considerable issues for the mixed-halogen blue emitting perovskite quantum dots light-emitting diodes(PeQLEDs).Here,an in situ surface pa...Low efficiency and spectral instability caused by the surface defects have been considerable issues for the mixed-halogen blue emitting perovskite quantum dots light-emitting diodes(PeQLEDs).Here,an in situ surface passivation to perovskite quantum dots(PeQDs)is realized by introducing the metal cations competitive lattice occupancy assisted with acid-etching,in which the longchain,insulating and weakly bond surface ligands are removed by addition of octanoic acid(OTAC).Meanwhile,the dissolved A-site cations(Na^(+))compete with the protonated oleyl amine and are subsequently anchored to the surface vacancies.The preadded lead bromide,acting as inorganic ligands,demonstrates strong bonding to the uncoordinated surface ions.The as-synthesized PeQDs show the boosted photoluminescence quantum yield(PLQY)and superior stability with longer lifetime.As a result,the PeQLEDs(470 nm)based on the OTAC-Na PeQDs exhibit an external quantum efficiency of 8.42%in the mixed halogen PeQDs(CsPb(Br_(x)Cl_(1−x))_(3)).Moreover,the device exhibits superior spectra stability with negligible shift.Our competition mechanism in combination with in situ passivation strategy paves a new way for improving the performance of blue PeQLEDs.展开更多
文摘The stable spectrum can be obtained when the voltage changes, which is a necessary condition for the white organic light emitting diode (WOLED) device to be widely used in the field of solid-state lighting. However, with the increase of voltage, the movement of the recombination zone (RZ) is inevitable because the perfect bipolar host material is difficult to obtain, which will redistribute the energy in the light emitting layer (EML) and affect the stability of the spectrum. We fabricate a series of ternary hybrid WOLEDs with a simple structure by inserting ultra-thin PO-T2T into the blue exciplex (TCTA:TPBi) to form the green interface exciplex. Without considering the movement of RZ, device B2 realizes the dynamic balance energy distribution in EML and stable spectrum by controlling two processes of the Dexter energy transfer and exciton capture. By modifying the doping ratio of the host material, we also find that the broadened RZ is helpful to further improve the spectral stability of the device. When the voltage changes from 3 V to 7 V, the change range of color coordinates is only (0.026, 0.025).
基金financially supported by National Natural Science Foundation of China (Nos.62305392 and 62305123)Independent Research and Development Project of Naval Engineering University (No.2023504050)the Nursery Plan Project of Navel University of Engineering (2022)。
文摘Optimization and simplification of optical systems represent a milestone in advancing the development of handheld and portable laser-induced breakdown spectroscopy(LIBS)systems towards smaller,more integrated forms.This research,for the first time,conducted a comprehensive optimization design and comparative analysis of three compact LIBS system optical paths:the paraxial optical path(OP),the off-axis OP,and the reflective OP.The differences in spectral intensity and stability among these paths were revealed,providing a scientific basis for selecting the optimal OP for LIBS systems.The research found that the paraxial OP excels in spectral performance and quantitative analysis accuracy,making it the preferred choice for compact LIBS systems.Specifically,the paraxial OP significantly enhances spectral intensity,achieving a 6 times improvement over the off-axis OP and an even more remarkable 150 times increase compared to the reflective OP,greatly enhancing detection sensitivity.Additionally,the relative standard deviation,spectral stability index,maintains a consistently low level,ranging from 10.9%to 13.4%,significantly outperforming the other two OPs and ensuring the reliability of analytical results.In the field of quantitative analysis,the paraxial OP also demonstrates higher accuracy,precision,and sensitivity,comparing to other OPs.The quantitative analysis models for Si,Cu,and Ti elements exhibit excellent fitting,providing users with high-quality quantitative analysis results that are of great significance for applications in material science,environmental monitoring,industrial inspection,and other fields.In summary,this study not only confirms the enormous application potential of the paraxial OP in compact LIBS systems but also provides valuable practical experience and theoretical support for the miniaturization and integration of LIBS systems.Looking ahead,with continuous technological advancements,the design of the paraxial OP is expected to further propel the widespread adoption of LIBS technology in portable,on-site detection applications.
基金Project supported by the National Natural Science Foundation of China (Grant No. U1174001)the Ministry of Education Scientific Research Foundation for Returned Scholars,China (Grant No. 20091001)+1 种基金the Scientific and Technological Plan of Guangzhou City,China (Grant No. 2010U1-D00131)the Natural Science Foundation of Guangdong Province,China (Grant No. S2011010003400)
文摘A strain-compensated InGaN quantum well（QW） active region employing a tensile AlGaN barrier is analyzed.Its spectral stability and efficiency droop for a dual-blue light-emitting diode（LED） are improved compared with those of the conventional InGaN/GaN QW dual-blue LEDs based on a stacking structure of two In0.18Ga0.82N/GaN QWs and two In0.12Ga0.88N/GaN QWs on the same sapphire substrate.It is found that the optimal performance is achieved when the Al composition of the strain-compensated AlGaN layer is 0.12 in blue QW and 0.21 in blue-violet QW.The improvement performance can be attributed to the strain-compensated InGaN-AlGaN/GaN QW,which can provide a better carrier confinement and effectively reduce leakage current.
基金supported by National Key R&D Program of China(Grant No.2022YFA1005900)National Natural Science Foundation of China(Grant Nos.12071284 and 12161131001)+1 种基金supported by National Natural Science Foundation of China(Grant No.11871334)Innovation Program of Shanghai Municipal Education Commission(Grant No.2021-01-07-00-02-E00087)。
文摘For a coupled slow-fast FitzHugh-Nagumo(FHN)equation derived from a reaction-diffusionmechanics(RDM)model,Holzer et al.(2013)studied the existence and stability of the travelling pulse,which consists of two fast orbit arcs and two slow ones,where one fast segment passes the unique fold point with algebraic decreasing and two slow ones follow normally hyperbolic critical curve segments.Shen and Zhang(2021)obtained the existence of the travelling pulse,whose two fast orbit arcs both exponentially decrease,and one of the slow orbit arcs could be normally hyperbolic or not at the origin.Here,we characterize both the nonlinear and spectral stability of this travelling pulse.
基金Research is supported by Science Foundation of the Education Commission of Beijing(No.KM201210017008)National Natural Science Foundation of China under Grants(No.61403034)Youth Foundation of Beijing Institute of Petrolchemical Technology(No.N10-04)
文摘The present paper deals with results of stability/instability of solitary waves with nonzero asymptotic value for a microstructure PDE. By the exact solitary wave solutions and detailed computations, we set up the explicit expression for the discrimination d′′（c）. Finally, a complete study of orbital stablity/instablity for the explicit exact solutions is given.
基金supported by financial aid from the National Natural Science Foundation of China(Nos.62474154 and 62205281)the Taishan Scholars Plan of Shangdong Province(tsqn201909084).
文摘Perovskite light-emitting diodes(PeLEDs)have emerged as a promising candidate for next-generation displays owing to their excellent luminescent properties and low cost.However,the development of deep blue PeLEDs has been hindered compared to red and green emission devices,largely due to the challenge of an unstable spectrum.In this work,we present a method for achieving spectral stabilization by using the organic ligand dipotassium 7-hydroxynaphthalene-1,3-disulphonate(G SALT).Combined with experimental results,we confirmed that the multiple interactions between G SALT and perovskite components played an important role in rearranging phase distribution and enhancing spectral stability.The fabricated deep blue PeLEDs demonstrated electrolu-minescence(EL)peak at 456 nm with Commission Internationale de I’Eclairage(CIE)coordinates of(0.149,0.063),meeting well with the Rec.2020 standard.Meanwhile,the peak external quantum efficiency(EQE)of 2.5% accompanied by the maximum luminance(Lmax)of 969.7 cd/m^(2) was achieved.The T50 lifetime was prolonged to 10 min under a constant current density of 12 mA/cm^(2),and there was no significant spectral shift in the EL spectra at high driving voltages ranging from 3.5 to 6.5 V.Furthermore,the films demonstrated stable photoluminescence spectra when subjected to ultraviolet excitation at 365 nm and continuous heating at 65°C.This study confirms the active role of organic compound ligands in quasi-two-dimensional(quasi-2D)perovskites and provides a new approach for developing stable ligands for the luminescent layer of perovskites in the future.
基金Key Research and Development Project of Anhui Province of China,Grant/Award Number:2023t07020005Anhui Innovation and Entrepreneurship Support Plan for Returned Overseas Students,Grant/Award Number:2022LCX018+2 种基金National Natural Science Foundation of China,Grant/Award Number:U1632151Open Project of Jiangsu Key Laboratory for Carbon‐Based Functional Materials&Devices,Grant/Award Number:KJS1802Natural Science Foundation of Anhui Province,China,Grant/Award Number:2308085QE137。
文摘Low efficiency and spectral instability caused by the surface defects have been considerable issues for the mixed-halogen blue emitting perovskite quantum dots light-emitting diodes(PeQLEDs).Here,an in situ surface passivation to perovskite quantum dots(PeQDs)is realized by introducing the metal cations competitive lattice occupancy assisted with acid-etching,in which the longchain,insulating and weakly bond surface ligands are removed by addition of octanoic acid(OTAC).Meanwhile,the dissolved A-site cations(Na^(+))compete with the protonated oleyl amine and are subsequently anchored to the surface vacancies.The preadded lead bromide,acting as inorganic ligands,demonstrates strong bonding to the uncoordinated surface ions.The as-synthesized PeQDs show the boosted photoluminescence quantum yield(PLQY)and superior stability with longer lifetime.As a result,the PeQLEDs(470 nm)based on the OTAC-Na PeQDs exhibit an external quantum efficiency of 8.42%in the mixed halogen PeQDs(CsPb(Br_(x)Cl_(1−x))_(3)).Moreover,the device exhibits superior spectra stability with negligible shift.Our competition mechanism in combination with in situ passivation strategy paves a new way for improving the performance of blue PeQLEDs.
