Metal halide perovskites have recently emerged as promising candidates for the next generation of X-ray detectors due to their excellent optoelectronic properties.Especially,two-dimensional(2D)perovskites afford many ...Metal halide perovskites have recently emerged as promising candidates for the next generation of X-ray detectors due to their excellent optoelectronic properties.Especially,two-dimensional(2D)perovskites afford many distinct properties,including remarkable structural diversity,high generation energy,and balanced large exciton binding energy.With the advantages of 2D materials and perovskites,it successfully reduces the decomposition and phase transition of perovskite and effectively suppresses ion migration.Meanwhile,the existence of a high hydrophobic spacer can block water molecules,thus making 2D perovskite obtain excellent stability.All of these advantages have attracted much attention in the field of X-ray detection.This review introduces the classification of 2D halide perovskites,summarizes the synthesis technology and performance characteristics of 2D perovskite X-ray direct detector,and briefly discusses the application of 2D perovskite in scintillators.Finally,this review also emphasizes the key challenges faced by 2D perovskite X-ray detectors in practical application and presents our views on its future development.展开更多
Benefiting from the excellent properties such as high photoluminescence quantum yield(PLQY), wide gamut range,and narrow emission linewidth, as well as low-temperature processability, metal halide perovskite quantum d...Benefiting from the excellent properties such as high photoluminescence quantum yield(PLQY), wide gamut range,and narrow emission linewidth, as well as low-temperature processability, metal halide perovskite quantum dots(QDs)have attracted wide attention from researchers. Despite tremendous progress has been made during the past several years,the commercialization of perovskite QDs-based LEDs(PeQLEDs) is still plagued by the instability. The ion migration in halide perovskites is recognized as the key factor causing the performance degradation of PeQLEDs. In this review, the elements species of ion migration, the effects of ion migration on device performance and stability, and effective strategies to hinder/mitigate ion migration in PeQLEDs are successively discussed. Finally, the forward insights on the future research are highlighted.展开更多
Photocurrent-voltage characterization is a crucial method for assessing key parameters in x-ray or y-ray semiconductor detectors,especially the carrier mobility lifetime product.However,the high biases during photocur...Photocurrent-voltage characterization is a crucial method for assessing key parameters in x-ray or y-ray semiconductor detectors,especially the carrier mobility lifetime product.However,the high biases during photocurrent measurements tend to cause severe ion migration,which can lead to the instability and inaccuracy of the test results.Given the mixed electronic-ionic charac teristics,it is imperative to devise novel methods capable of precisely measuring photocurrentvoltage characteristics under high bias conditions,free from interference caused by ion migration.In this paper,pulsed bias is employed to explore the photocurrent-voltage characteristics of MAPbBr_(3) single crystals.The method yields stable photocurrent-voltage characteristics at a pulsed bias of up to 30 V,proving to be effective in mitigating ion migration.Through fitting the modified Hecht equation,we determined the mobility lifetime products of 1.0×10^(2) cm^(2)·V^(-1)for hole and 2.78×10~(-3)cm^(2)·V^(-1)for electron.This approach offers a promising solution for accurately measuring the transport properties of carriers in perovskite.展开更多
Metal halide perovskites are emerging as the most promising candidate for the next-generation Photovoltaics(PV)materials,due to their superior optoelectronic properties and low cost.However,the resulting Perovskite so...Metal halide perovskites are emerging as the most promising candidate for the next-generation Photovoltaics(PV)materials,due to their superior optoelectronic properties and low cost.However,the resulting Perovskite solar cells(PSCs)suffer from poor stability.In particular,the temperature and light activated ionic defects within the perovskite lattice,as well as electric-field-induced migration of ionic defects,make the PSCs unstable at operating condition,even with device encapsulation.There is no doubt that the investigation of ion migration is crucial for the development of PSCs with high intrinsic stability.In this review,we first briefly introduce the origin and pathways of ion migration,and also the essential characterization methods to identify ion migration.Next,we discuss the impact of ion migration on the perovskite films and cells with respect to photoelectric properties and stability.Then,several representative strategies to suppress ion migration are systematically summarized in the context of composition engineering,additive engineering and interface engineering,with an in-depth understanding on the underlying mechanisms which may provide more clues for further fabrication of PSCs with improved stability.Finally,a perspective with some suggestion on future research directions and chemical approaches are provided to alleviate ion migration in perovskite materials and the entire devices.展开更多
Hybrid halide perovskites have great potential for applications in optoelectronic devices.However,the typical ion migration in perovskite could lead to the non-repeatability of electrical measurement,instability of ma...Hybrid halide perovskites have great potential for applications in optoelectronic devices.However,the typical ion migration in perovskite could lead to the non-repeatability of electrical measurement,instability of material,and degradation of device performance.The basic current–voltage behavior of perovskite materials is intricate due to the mixed electronic–ionic characteristic,which is still poorly understood in these semiconductors.Developing novel measurement schematic is a promising solution to obtain the intrinsic electrical performance without the interference of ion migration.Herein,we explore the pulse-voltage(PV)method on methylammonium lead tribromide single crystals to protect the device from the ion migration.A guideline is summarized through the analysis of measurement history and condition parameters.The influence of the ion migration on current–voltage measurement,such as repeatability and hysteresis loop,is under controlled.An application of the PV method is demonstrated on the activation energy of conductivity.The abruption of activation energy still exists near the phase transition temperature despite the ion migration is excluded by the PV method,introducing new physical insight on the current–voltage behavior of perovskite materials.The guideline on PV method will be beneficial for measuring halide perovskite materials and developing optoelectronic applications with new technique schematic.展开更多
The device preconditioning dependent hysteresis and the consequential performance degradation hinder the actual performance and stability of the perovskite solar cells. Ion migration and charge trapping in the perovsk...The device preconditioning dependent hysteresis and the consequential performance degradation hinder the actual performance and stability of the perovskite solar cells. Ion migration and charge trapping in the perovskite with large contribution from grain boundaries are the most common interpretations for the hysteresis. Yet, the high performing devices often include intermediate hole and electron transporting layers, which can further complicate the dynamical process in the device. Here, by using Kelvin Probe Force Microscopy and Confocal Photoluminescence Microscopy, we elucidate the impact of chargetransporting layers and excess MAI on the spatial and temporal variations of the photovoltage on the MAPbI3-based solar cells. By studying the devices layer by layer, we found that the light-induced ion migration occurs predominantly in the presence of an imbalanced charge extraction in the solar cells, and the charge transporting layers play crucial role in suppressing it. Careful selection and processing of the electron and hole-transporting materials are thus essential for making perovskite solar cells free from the ion migration effect.展开更多
Owing to the features(high safety,inexpensive and environmental friendliness)of aqueous rechargeable Mg-ion batteries(ARMIBs),they have drawn extensive attention in the future energy storage systems.However,the poor M...Owing to the features(high safety,inexpensive and environmental friendliness)of aqueous rechargeable Mg-ion batteries(ARMIBs),they have drawn extensive attention in the future energy storage systems.However,the poor Mg^(2+)migration kinetics during the Mg^(2+)intercalation/extraction still hinders the progress of developing suitable cathode materials.Herein,a layered buserite Mg-Mn oxide(MMO)material with large interlayer space(~9.70A)and low-crystalline structure is studied as a high-performance cathode in ARMIBs.Compared with the counterpart,the Mg^(2+)migration kinetics of the MMO cathode can be enhanced by its unique structure(bigger interlayer spacing and low-crystalline structure).The layered buserite MMO as a high-performance ARMIBs cathode exhibits high Mg storage capacity(50 mAg^(-1):169.3 mAh g^(-1)),excellent rate capability(1000 mAg^(-1):98.3 mAh g^(-1)),and fast Mg^(2+)migration(an average diffusion coefficient:~4.21×10-^(10)cm^(2)s^(-1))in 0.5 M MgCl_(2)aqueous electrolyte.Moreover,the MMO-1//AC full battery achieved a high discharge capacity(100 mAg^(-1):111 mAh g^(-1)),and an ignored fading over 5000 cycles(1000 mAg^(-1)).Therefore,layered Mg-Mn oxide with large interlayer space may break a new path to develop the promising ARMIBs.展开更多
To explore the distribution of and the mechanical properties(compressive strength)of the hardened body of alkali slag-fly ash cementitious materials,this study was conducted by using the XRD,FTIR,SEM/EDS,and other tes...To explore the distribution of and the mechanical properties(compressive strength)of the hardened body of alkali slag-fly ash cementitious materials,this study was conducted by using the XRD,FTIR,SEM/EDS,and other test methods in three conditions:airtight drying(AD),airtight immersion(AI),and airtight soaking(AS).The 1D distribution law of free of hardened body under standard curing conditions was explored.The experimental results show that under standard curing conditions,the 1D distribution of within 0d-3 d shows a∨-shaped distribution,within 3-7 d show a∧-shaped distribution,and within 7-28 d tends to be balanced.The test results of leaching rate show that the free was the most stable under AD conditions and the hardened body bound the most by XRD,FTIR and SEM/EDS.And the compressive strength of the hardened body was the highest.The compressive strength of 28th reached 95.9 MPa.The definite distribution of provides an important reference for the strength development and durability evaluation of the hardened body of alkaliexcited cementitious materials.展开更多
Layered lithium-rich manganese-based oxide(LRMO)has the limitation of inevitable evolution of lattice oxygen release and layered structure transformation.Herein,a multilayer reconstruction strategy is applied to LRMO ...Layered lithium-rich manganese-based oxide(LRMO)has the limitation of inevitable evolution of lattice oxygen release and layered structure transformation.Herein,a multilayer reconstruction strategy is applied to LRMO via facile pyrolysis of potassium Prussian blue.The multilayer interface is visually observed using an atomic-resolution scanning transmission electron microscope and a high-resolution transmission electron microscope.Combined with the electrochemical characterization,the redox of lattice oxygen is suppressed during the initial charging.In situ X-ray diffraction and the high-resolution transmission electron microscope demonstrate that the suppressed evolution of lattice oxygen eliminates the variation in the unit cell parameters during initial(de)lithiation,which further prevents lattice distortion during long cycling.As a result,the initial Coulombic efficiency of the modified LRMO is up to 87.31%,and the rate capacity and long-term cycle stability also improved considerably.In this work,a facile surface reconstruction strategy is used to suppress vigorous anionic redox,which is expected to stimulate material design in high-performance lithium ion batteries.展开更多
Narrowband photodetectors conventionally rely on optical structure design orbandpass filters to achieve the narrowband regime. Recently, a strategy forfilterless narrowband photoresponse based on the charge collection...Narrowband photodetectors conventionally rely on optical structure design orbandpass filters to achieve the narrowband regime. Recently, a strategy forfilterless narrowband photoresponse based on the charge collection narrowing(CCN) mechanism was reported. However, the CCN strategy requires an electrically and optically “thick” photoactive layer, which poses challenges in controlling the narrowband photoresponse. Here we propose a novel strategy forconstructing narrowband photodetectors by leveraging the inherent ion migration in perovskites, which we term “band modulation narrowing” (BMN). Bymanipulating the ion migration with external stimuli such as illumination,temperature, and bias voltage, we can regulate in situ the energy-band structure of perovskite photodetectors (PPDs) and hence their spectral response.Combining the Fermi energy levels obtained by the Kelvin probe force microscopy, the internal potential profiles from solar cell capacitance simulator simulation, and the anion accumulation revealed by the transient ion-drifttechnique, we discover two critical mechanisms behind our BMN strategy: theextension of an optically active but electronically dead region proximal to the top electrode and the down-bending energy bands near the electron transportlayer. Our findings offer a case for harnessing the often-annoying ionmigration for developing advanced narrowband PPDs.展开更多
Enhancing ion conductance and controlling transport pathway in organic electrolyte could be used to modulate ionic kinetics to handle signals. In a Pt/Poly(3-hexylthiophene-2,5-diyl)/Polyethylene?Li CF3SO3/Pt hetero-j...Enhancing ion conductance and controlling transport pathway in organic electrolyte could be used to modulate ionic kinetics to handle signals. In a Pt/Poly(3-hexylthiophene-2,5-diyl)/Polyethylene?Li CF3SO3/Pt hetero-junction, the electrolyte layer handled at high temperature showed nano-fiber microstructures accompanied with greatly improved salt solubility. Ions with high mobility were confined in the nano-fibrous channels leading to the semiconducting polymer layer,which is favorable for modulating dynamic doping at the semiconducting polymer/electrolyte interface by pulse frequency.Such a device realized synaptic-like frequency selectivity, i.e., depression at low frequency stimulation but potentiation at high-frequency stimulation.展开更多
Based on the experimental data of KY 3F 10∶Tm 3+ reported by Diaf, K ushida′s spectral overlap model (SOM) of energy transfer between J-multipl ets was studied. Firstly, with the help of the Inokuti-Hirayama an...Based on the experimental data of KY 3F 10∶Tm 3+ reported by Diaf, K ushida′s spectral overlap model (SOM) of energy transfer between J-multipl ets was studied. Firstly, with the help of the Inokuti-Hirayama and Yokota-Tan imoto models, the luminescence decay curve of 3H 4 of Tm 3+ ion was fitted, and the fitted values of corresponding interaction parameters C D A of energy transfer and C DD of energy migration were obtained. Seco ndly, by compared with Kushida′s SOM in which the relevant Judd-Ofelt approxim ative transition rates are known, the average overlap integrals of S DD and S DA were obtained. For S DD, how to treat the contributi on of the electronic-dipole (ED) crystal field transition forbidden by C 4v site symmetry in the calculation of S DD was discussed. For S DA we suggested that, by including the contribution of the phonon sideba nds in the analysis of oscillator strength of transition, Kushida′s SOM of ED- ED resonant energy transfer rate can be extended to non-resonant phonon-assist ed D-A energy transfer. The strengths and widths of phonon sidebands in this ex ample were discussed, and the results were reasonably good.展开更多
So far,it's been widely acknowledged that the Pb I2decomposition under illumination mainly accounts for the degradation of perovskite solar cells(PSCs)under maximum power point(MPP)tracking condition.However,PSCs ...So far,it's been widely acknowledged that the Pb I2decomposition under illumination mainly accounts for the degradation of perovskite solar cells(PSCs)under maximum power point(MPP)tracking condition.However,PSCs without excess Pb I2were also reported to deteriorate rapidly under the same condition.Here,we demonstrate that the key to enhance PSCs stability under MPP tracking condition is not to have fascinating surface morphology with effective suppression of nonradiative recombination traps but to prevent the migration of iodine ion(I-)under light illumination.By partially substituting methylammonium chloride(MACl)with methylammonium iodide(MAI)and simutaneouly introducing I2during the sequential deposition,the iodine vacancies in perovskite films are substantially suppressed,thereby limiting the pathways for I^(-)migration.As a consequence,PSCs with efficiency of 24.28%are fabricated with remarkably enhanced working stability.展开更多
The inevitable ion migration that occurs within ionic polycrystalline perovskite film results in inferior longterm stability of perovskite solar cells(PVSCs)that cannot meet the commercial requirements.Here,a novel po...The inevitable ion migration that occurs within ionic polycrystalline perovskite film results in inferior longterm stability of perovskite solar cells(PVSCs)that cannot meet the commercial requirements.Here,a novel poly(ionic liquid)named poly-1-vinyl-3-propyltrimethoxysilane imidazolium chloride(PImIL-SiO)is first introduced into perovskite to strengthen grain boundaries(GBs)and construct dual-functional barriers against internal ion migration and external moisture erosion for fabricating highly efficient and stable PVSCs.PImIL-SiO-containing imidazoliumcations and pendant siloxane groups contribute to passivation of bulk defects and anchoring of GBs,which effectively hinders ion migration channels,thus reducing perovskite film phase separation and device hysteresis.Furthermore,the intrinsically hydrophobic PImIL-SiO automatically forms a secondary protective barrier to endow the perovskite film with ultrahigh moisture corrosion resistance through the hydrolyzation reaction of siloxane with the permeated moisture.Consequently,the PImIL-SiO-modified PVSCs achieve a champion power conversion efficiency(PCE)of 22.46%,accompaniedby excellent thermal andhumidity stabilities where the non-encapsulated devices retain 87%of the initial PCE after aging at 85℃for 250 h and>85%of the initial PCE over 1100 h in air with a relative humidity of 50–70%.展开更多
Ionic transport in organometal halide perovskites is of vital importance because it dominates anomalous phenomena in perovskite solar cells,from hysteresis to switchable photovoltaic effects.However,excited state ioni...Ionic transport in organometal halide perovskites is of vital importance because it dominates anomalous phenomena in perovskite solar cells,from hysteresis to switchable photovoltaic effects.However,excited state ionic transport under illumination has remained elusive,although it is essential for understanding the unusual light-induced effects(light-induced self-poling,photo-induced halide segregation and slow photoconductivity response)in organometal halide perovskites for optoelectronic applications.Here,we quantitatively demonstrate light-enhanced ionic transport in CH3NH3PbI3 over a wide temperature range of 17–295 K,which reveals a reduction in ionic transport activation energy by approximately a factor of five(from 0.82 to 0.15 eV)under illumination.The pure ionic conductance is obtained by separating it from the electronic contribution in cryogenic galvanostatic and voltage-current measurements.On the basis of these findings,we design a novel light-assisted method of catalyzing ionic interdiffusion between CH3NH3I and PbI2 stacking layers in sequential deposition perovskite synthesis.X-ray diffraction patterns indicate a significant reduction of PbI2 residue in the optimized CH3NH3PbI3 thin film produced via lightassisted sequential deposition,and the resulting solar cell efficiency is increased by over 100%(7.5%–15.7%)with little PbI2 residue.This new method enables fine control of the reaction depth in perovskite synthesis and,in turn,supports light-enhanced ionic transport.展开更多
With the support of the National Natural Science Foundation of China,two original studies by the research group led by Prof.Gu Lin(谷林)and Prof.Zhang Qinghua(张庆华)from the Institute of Physics,Chinese Academy of Sc...With the support of the National Natural Science Foundation of China,two original studies by the research group led by Prof.Gu Lin(谷林)and Prof.Zhang Qinghua(张庆华)from the Institute of Physics,Chinese Academy of Sciences demonstrate the in-situ atomic-scale electrically induced展开更多
The rational design of electrodes is the key to achieving ultrahigh-power performance in electrochemical energy storage devices.Recently,we have constructed well-organized and integrated three-dimensional(3D)carbon tu...The rational design of electrodes is the key to achieving ultrahigh-power performance in electrochemical energy storage devices.Recently,we have constructed well-organized and integrated three-dimensional(3D)carbon tube(CT)grids(3D-CTGs)using a 3D porous anodic aluminum oxide template-assisted method as electrodes of electrical double-layer capacitors(EDLCs),showing excellent frequency response performance.The unique design warrants fast ion migration channels,excellent electronic conductivity,and good structural stability.This study achieved one of the highest carbon-based ultrahigh-power EDLCs with the 3D-CTG electrodes,resulting in ultrahigh power of 437 and 1708 W·cm−3 with aqueous and organic electrolytes,respectively.Capacitors constructed with these electrodes would have important application prospects in the ultrahigh-power output.The rational design and fabrication of the 3D-CTGs electrodes have demonstrated their capability to build capacitors with ultrahighpower performance and open up new possibilities for applications requiring high-power output.展开更多
Although perovskite light-emitting diodes(PeLEDs)have seen unprecedented development in device efciency over the past decade,they sufer signifcantly from poor operational stability.This is especially true for blue PeL...Although perovskite light-emitting diodes(PeLEDs)have seen unprecedented development in device efciency over the past decade,they sufer signifcantly from poor operational stability.This is especially true for blue PeLEDs,whose operational lifetime remains orders of magnitude behind their green and red counterparts.Here,we systematically investigate this efciency-stability discrepancy in a series of green-to blue-emitting PeLEDs based on mixed Br/Cl-perovskites.We fnd that chloride incorporation,while having only a limited impact on efciency,detrimentally afects device stability even in small amounts.Device lifetime drops exponentially with increasing Cl-content,accompanied by an increased rate of change in electrical properties during operation.We ascribe this phenomenon to an increased mobility of halogen ions in the mixed-halide lattice due to an increased chemically and structurally disordered landscape with reduced migration barriers.Our results indicate that the stability enhancement for PeLEDs might require diferent strategies from those used for improving efciency.展开更多
基金This work was funded by the National Natural Science Foundation of China(22279049 and 12247101)the Fundamental Research Funds for the Central Universities(lzujbky-2021-it31,lzujbky-2021-ct15 and lzujbky-2021-sp69)+1 种基金the calculation work was supported by Supercomputing Center of Lanzhou Universitythe Gansu Province Outstanding Doctoral Student Program(22JR5RA435).
文摘Metal halide perovskites have recently emerged as promising candidates for the next generation of X-ray detectors due to their excellent optoelectronic properties.Especially,two-dimensional(2D)perovskites afford many distinct properties,including remarkable structural diversity,high generation energy,and balanced large exciton binding energy.With the advantages of 2D materials and perovskites,it successfully reduces the decomposition and phase transition of perovskite and effectively suppresses ion migration.Meanwhile,the existence of a high hydrophobic spacer can block water molecules,thus making 2D perovskite obtain excellent stability.All of these advantages have attracted much attention in the field of X-ray detection.This review introduces the classification of 2D halide perovskites,summarizes the synthesis technology and performance characteristics of 2D perovskite X-ray direct detector,and briefly discusses the application of 2D perovskite in scintillators.Finally,this review also emphasizes the key challenges faced by 2D perovskite X-ray detectors in practical application and presents our views on its future development.
基金supported by the Natural Natural Science Foundation of China (Grant Nos.61904081 and 51672132)the Natural Science Foundation of Jiangsu Province,China (Grant No.BK20190449)the Postdoctoral Research Funding Program of Jiangsu Province,China (Grant No.2020Z144)。
文摘Benefiting from the excellent properties such as high photoluminescence quantum yield(PLQY), wide gamut range,and narrow emission linewidth, as well as low-temperature processability, metal halide perovskite quantum dots(QDs)have attracted wide attention from researchers. Despite tremendous progress has been made during the past several years,the commercialization of perovskite QDs-based LEDs(PeQLEDs) is still plagued by the instability. The ion migration in halide perovskites is recognized as the key factor causing the performance degradation of PeQLEDs. In this review, the elements species of ion migration, the effects of ion migration on device performance and stability, and effective strategies to hinder/mitigate ion migration in PeQLEDs are successively discussed. Finally, the forward insights on the future research are highlighted.
基金Project supported by the National Natural Science Foundation of China (Grant No.62104234)Shanghai Explorer Program (Grant No.22TS1400100)。
文摘Photocurrent-voltage characterization is a crucial method for assessing key parameters in x-ray or y-ray semiconductor detectors,especially the carrier mobility lifetime product.However,the high biases during photocurrent measurements tend to cause severe ion migration,which can lead to the instability and inaccuracy of the test results.Given the mixed electronic-ionic charac teristics,it is imperative to devise novel methods capable of precisely measuring photocurrentvoltage characteristics under high bias conditions,free from interference caused by ion migration.In this paper,pulsed bias is employed to explore the photocurrent-voltage characteristics of MAPbBr_(3) single crystals.The method yields stable photocurrent-voltage characteristics at a pulsed bias of up to 30 V,proving to be effective in mitigating ion migration.Through fitting the modified Hecht equation,we determined the mobility lifetime products of 1.0×10^(2) cm^(2)·V^(-1)for hole and 2.78×10~(-3)cm^(2)·V^(-1)for electron.This approach offers a promising solution for accurately measuring the transport properties of carriers in perovskite.
基金supported by the National Key Research and Development Program of China(2017YFA0206701,2020YFB1506400)the National Natural Science Foundation of China(51972004,21975028)the China Postdoctoral Science Foundation(2020M670040)。
文摘Metal halide perovskites are emerging as the most promising candidate for the next-generation Photovoltaics(PV)materials,due to their superior optoelectronic properties and low cost.However,the resulting Perovskite solar cells(PSCs)suffer from poor stability.In particular,the temperature and light activated ionic defects within the perovskite lattice,as well as electric-field-induced migration of ionic defects,make the PSCs unstable at operating condition,even with device encapsulation.There is no doubt that the investigation of ion migration is crucial for the development of PSCs with high intrinsic stability.In this review,we first briefly introduce the origin and pathways of ion migration,and also the essential characterization methods to identify ion migration.Next,we discuss the impact of ion migration on the perovskite films and cells with respect to photoelectric properties and stability.Then,several representative strategies to suppress ion migration are systematically summarized in the context of composition engineering,additive engineering and interface engineering,with an in-depth understanding on the underlying mechanisms which may provide more clues for further fabrication of PSCs with improved stability.Finally,a perspective with some suggestion on future research directions and chemical approaches are provided to alleviate ion migration in perovskite materials and the entire devices.
基金Project supported by the National Natural Science Foundation of China(Grant No.61805263)Shanghai Sailing Program,China(Grant No.18YF1426400).
文摘Hybrid halide perovskites have great potential for applications in optoelectronic devices.However,the typical ion migration in perovskite could lead to the non-repeatability of electrical measurement,instability of material,and degradation of device performance.The basic current–voltage behavior of perovskite materials is intricate due to the mixed electronic–ionic characteristic,which is still poorly understood in these semiconductors.Developing novel measurement schematic is a promising solution to obtain the intrinsic electrical performance without the interference of ion migration.Herein,we explore the pulse-voltage(PV)method on methylammonium lead tribromide single crystals to protect the device from the ion migration.A guideline is summarized through the analysis of measurement history and condition parameters.The influence of the ion migration on current–voltage measurement,such as repeatability and hysteresis loop,is under controlled.An application of the PV method is demonstrated on the activation energy of conductivity.The abruption of activation energy still exists near the phase transition temperature despite the ion migration is excluded by the PV method,introducing new physical insight on the current–voltage behavior of perovskite materials.The guideline on PV method will be beneficial for measuring halide perovskite materials and developing optoelectronic applications with new technique schematic.
基金supported by the MEYS project, Czech Republic [No.CZ.02.1.01/0.0/0.0/15_003/0000464 (CAP)]the ’Severo Ochoa’ program for Centers of Excellence in R&D [MINECO, Grant SEV2016-0686]+3 种基金the Natural Science Foundation of Jiangsu Province, China [BK20180601]the Fundamental Research Funds for the Central Universities [JUSRP11834, JUSRP11834B]the Jiangsu Postdoctoral Science Foundation [2018K112C, 2018K113C]funding from the Lab and Equipment Management of Jiangnan University (JDSYS201906)。
文摘The device preconditioning dependent hysteresis and the consequential performance degradation hinder the actual performance and stability of the perovskite solar cells. Ion migration and charge trapping in the perovskite with large contribution from grain boundaries are the most common interpretations for the hysteresis. Yet, the high performing devices often include intermediate hole and electron transporting layers, which can further complicate the dynamical process in the device. Here, by using Kelvin Probe Force Microscopy and Confocal Photoluminescence Microscopy, we elucidate the impact of chargetransporting layers and excess MAI on the spatial and temporal variations of the photovoltage on the MAPbI3-based solar cells. By studying the devices layer by layer, we found that the light-induced ion migration occurs predominantly in the presence of an imbalanced charge extraction in the solar cells, and the charge transporting layers play crucial role in suppressing it. Careful selection and processing of the electron and hole-transporting materials are thus essential for making perovskite solar cells free from the ion migration effect.
基金financially supported by the Fundamental Research Funds for the Central Universities(NO.2021CDJXDJH003)Guangdong National Technology Co.,Ltd.
文摘Owing to the features(high safety,inexpensive and environmental friendliness)of aqueous rechargeable Mg-ion batteries(ARMIBs),they have drawn extensive attention in the future energy storage systems.However,the poor Mg^(2+)migration kinetics during the Mg^(2+)intercalation/extraction still hinders the progress of developing suitable cathode materials.Herein,a layered buserite Mg-Mn oxide(MMO)material with large interlayer space(~9.70A)and low-crystalline structure is studied as a high-performance cathode in ARMIBs.Compared with the counterpart,the Mg^(2+)migration kinetics of the MMO cathode can be enhanced by its unique structure(bigger interlayer spacing and low-crystalline structure).The layered buserite MMO as a high-performance ARMIBs cathode exhibits high Mg storage capacity(50 mAg^(-1):169.3 mAh g^(-1)),excellent rate capability(1000 mAg^(-1):98.3 mAh g^(-1)),and fast Mg^(2+)migration(an average diffusion coefficient:~4.21×10-^(10)cm^(2)s^(-1))in 0.5 M MgCl_(2)aqueous electrolyte.Moreover,the MMO-1//AC full battery achieved a high discharge capacity(100 mAg^(-1):111 mAh g^(-1)),and an ignored fading over 5000 cycles(1000 mAg^(-1)).Therefore,layered Mg-Mn oxide with large interlayer space may break a new path to develop the promising ARMIBs.
基金Funded by the Natural Sciences Foundation of China(No.51808025)the Pyramid Talent Training Project of BUCEA(No.JDYC20200329)。
文摘To explore the distribution of and the mechanical properties(compressive strength)of the hardened body of alkali slag-fly ash cementitious materials,this study was conducted by using the XRD,FTIR,SEM/EDS,and other test methods in three conditions:airtight drying(AD),airtight immersion(AI),and airtight soaking(AS).The 1D distribution law of free of hardened body under standard curing conditions was explored.The experimental results show that under standard curing conditions,the 1D distribution of within 0d-3 d shows a∨-shaped distribution,within 3-7 d show a∧-shaped distribution,and within 7-28 d tends to be balanced.The test results of leaching rate show that the free was the most stable under AD conditions and the hardened body bound the most by XRD,FTIR and SEM/EDS.And the compressive strength of the hardened body was the highest.The compressive strength of 28th reached 95.9 MPa.The definite distribution of provides an important reference for the strength development and durability evaluation of the hardened body of alkaliexcited cementitious materials.
基金This work was financially supported by the High‐level Talents'Discipline Construction Fund of Shandong University(31370089963078)the Shandong Provincial Science and Technology Major Project(2018JM RH0211 and 2017CXGC1010)+3 种基金the Research Funds of Shandong University(10000089395121)the Natural Science Foundation of Shandong Province(ZR2019MEM052 and ZR2017MEM002)The National Natural Science Foundation of China(grant no.52002287)the Start‐up Funding of Wenzhou University are acknowledged.
文摘Layered lithium-rich manganese-based oxide(LRMO)has the limitation of inevitable evolution of lattice oxygen release and layered structure transformation.Herein,a multilayer reconstruction strategy is applied to LRMO via facile pyrolysis of potassium Prussian blue.The multilayer interface is visually observed using an atomic-resolution scanning transmission electron microscope and a high-resolution transmission electron microscope.Combined with the electrochemical characterization,the redox of lattice oxygen is suppressed during the initial charging.In situ X-ray diffraction and the high-resolution transmission electron microscope demonstrate that the suppressed evolution of lattice oxygen eliminates the variation in the unit cell parameters during initial(de)lithiation,which further prevents lattice distortion during long cycling.As a result,the initial Coulombic efficiency of the modified LRMO is up to 87.31%,and the rate capacity and long-term cycle stability also improved considerably.In this work,a facile surface reconstruction strategy is used to suppress vigorous anionic redox,which is expected to stimulate material design in high-performance lithium ion batteries.
基金National Natural Science Foundation of China,Grant/Award Numbers:21972006,22275180,U2001217,22261160370,52202182Shenzhen Peacock plan,Grant/Award Number:KQTD2016053015544057+1 种基金Shenzhen Innovation Fund,Grant/Award Number:JCYJ20220818101018038Natural Sciences and Engineering Research Council of Canada,Grant/Award Number:RGPIN-2020-04239。
文摘Narrowband photodetectors conventionally rely on optical structure design orbandpass filters to achieve the narrowband regime. Recently, a strategy forfilterless narrowband photoresponse based on the charge collection narrowing(CCN) mechanism was reported. However, the CCN strategy requires an electrically and optically “thick” photoactive layer, which poses challenges in controlling the narrowband photoresponse. Here we propose a novel strategy forconstructing narrowband photodetectors by leveraging the inherent ion migration in perovskites, which we term “band modulation narrowing” (BMN). Bymanipulating the ion migration with external stimuli such as illumination,temperature, and bias voltage, we can regulate in situ the energy-band structure of perovskite photodetectors (PPDs) and hence their spectral response.Combining the Fermi energy levels obtained by the Kelvin probe force microscopy, the internal potential profiles from solar cell capacitance simulator simulation, and the anion accumulation revealed by the transient ion-drifttechnique, we discover two critical mechanisms behind our BMN strategy: theextension of an optically active but electronically dead region proximal to the top electrode and the down-bending energy bands near the electron transportlayer. Our findings offer a case for harnessing the often-annoying ionmigration for developing advanced narrowband PPDs.
基金supported by National Natural Science foundation of China (Grant Nos. 51371103 and 51231004)National Basic Research Program of China (Grant No. 2010CB832905)+1 种基金National Hi-tech (R&D) Project of China (Grant Nos. 2012AA03A706, 2013AA030801)the Research Project of Chinese Ministry of Education (No. 113007A)
文摘Enhancing ion conductance and controlling transport pathway in organic electrolyte could be used to modulate ionic kinetics to handle signals. In a Pt/Poly(3-hexylthiophene-2,5-diyl)/Polyethylene?Li CF3SO3/Pt hetero-junction, the electrolyte layer handled at high temperature showed nano-fiber microstructures accompanied with greatly improved salt solubility. Ions with high mobility were confined in the nano-fibrous channels leading to the semiconducting polymer layer,which is favorable for modulating dynamic doping at the semiconducting polymer/electrolyte interface by pulse frequency.Such a device realized synaptic-like frequency selectivity, i.e., depression at low frequency stimulation but potentiation at high-frequency stimulation.
文摘Based on the experimental data of KY 3F 10∶Tm 3+ reported by Diaf, K ushida′s spectral overlap model (SOM) of energy transfer between J-multipl ets was studied. Firstly, with the help of the Inokuti-Hirayama and Yokota-Tan imoto models, the luminescence decay curve of 3H 4 of Tm 3+ ion was fitted, and the fitted values of corresponding interaction parameters C D A of energy transfer and C DD of energy migration were obtained. Seco ndly, by compared with Kushida′s SOM in which the relevant Judd-Ofelt approxim ative transition rates are known, the average overlap integrals of S DD and S DA were obtained. For S DD, how to treat the contributi on of the electronic-dipole (ED) crystal field transition forbidden by C 4v site symmetry in the calculation of S DD was discussed. For S DA we suggested that, by including the contribution of the phonon sideba nds in the analysis of oscillator strength of transition, Kushida′s SOM of ED- ED resonant energy transfer rate can be extended to non-resonant phonon-assist ed D-A energy transfer. The strengths and widths of phonon sidebands in this ex ample were discussed, and the results were reasonably good.
基金the support of the National High Technology Research and Development Program(2015AA050601)the National Natural Science Foundation of China(12134010,62074117,61904126,12174290)+1 种基金the Natural Science Foundation of Hubei Province,China(Grant No.2019AAA020)the Fundamental Research Funds for the Central Universities(2042021kf0228)。
文摘So far,it's been widely acknowledged that the Pb I2decomposition under illumination mainly accounts for the degradation of perovskite solar cells(PSCs)under maximum power point(MPP)tracking condition.However,PSCs without excess Pb I2were also reported to deteriorate rapidly under the same condition.Here,we demonstrate that the key to enhance PSCs stability under MPP tracking condition is not to have fascinating surface morphology with effective suppression of nonradiative recombination traps but to prevent the migration of iodine ion(I-)under light illumination.By partially substituting methylammonium chloride(MACl)with methylammonium iodide(MAI)and simutaneouly introducing I2during the sequential deposition,the iodine vacancies in perovskite films are substantially suppressed,thereby limiting the pathways for I^(-)migration.As a consequence,PSCs with efficiency of 24.28%are fabricated with remarkably enhanced working stability.
基金supported by National Natural Science Foundation of China(NSFC)(grant nos.52063019,51973088,51833004,U20A20128).
文摘The inevitable ion migration that occurs within ionic polycrystalline perovskite film results in inferior longterm stability of perovskite solar cells(PVSCs)that cannot meet the commercial requirements.Here,a novel poly(ionic liquid)named poly-1-vinyl-3-propyltrimethoxysilane imidazolium chloride(PImIL-SiO)is first introduced into perovskite to strengthen grain boundaries(GBs)and construct dual-functional barriers against internal ion migration and external moisture erosion for fabricating highly efficient and stable PVSCs.PImIL-SiO-containing imidazoliumcations and pendant siloxane groups contribute to passivation of bulk defects and anchoring of GBs,which effectively hinders ion migration channels,thus reducing perovskite film phase separation and device hysteresis.Furthermore,the intrinsically hydrophobic PImIL-SiO automatically forms a secondary protective barrier to endow the perovskite film with ultrahigh moisture corrosion resistance through the hydrolyzation reaction of siloxane with the permeated moisture.Consequently,the PImIL-SiO-modified PVSCs achieve a champion power conversion efficiency(PCE)of 22.46%,accompaniedby excellent thermal andhumidity stabilities where the non-encapsulated devices retain 87%of the initial PCE after aging at 85℃for 250 h and>85%of the initial PCE over 1100 h in air with a relative humidity of 50–70%.
基金supported by the National 973 Project(2013CB932602,MOST)the Ministry of Science and Technology of China and the National Natural Science Foundation of China(NSFC51272007,61571015,11327902,11234001,91433102 and 51522201)+1 种基金the Beijing Nova Program(XX2013003)the Program for New Century Excellent Talents in University of China.
文摘Ionic transport in organometal halide perovskites is of vital importance because it dominates anomalous phenomena in perovskite solar cells,from hysteresis to switchable photovoltaic effects.However,excited state ionic transport under illumination has remained elusive,although it is essential for understanding the unusual light-induced effects(light-induced self-poling,photo-induced halide segregation and slow photoconductivity response)in organometal halide perovskites for optoelectronic applications.Here,we quantitatively demonstrate light-enhanced ionic transport in CH3NH3PbI3 over a wide temperature range of 17–295 K,which reveals a reduction in ionic transport activation energy by approximately a factor of five(from 0.82 to 0.15 eV)under illumination.The pure ionic conductance is obtained by separating it from the electronic contribution in cryogenic galvanostatic and voltage-current measurements.On the basis of these findings,we design a novel light-assisted method of catalyzing ionic interdiffusion between CH3NH3I and PbI2 stacking layers in sequential deposition perovskite synthesis.X-ray diffraction patterns indicate a significant reduction of PbI2 residue in the optimized CH3NH3PbI3 thin film produced via lightassisted sequential deposition,and the resulting solar cell efficiency is increased by over 100%(7.5%–15.7%)with little PbI2 residue.This new method enables fine control of the reaction depth in perovskite synthesis and,in turn,supports light-enhanced ionic transport.
文摘With the support of the National Natural Science Foundation of China,two original studies by the research group led by Prof.Gu Lin(谷林)and Prof.Zhang Qinghua(张庆华)from the Institute of Physics,Chinese Academy of Sciences demonstrate the in-situ atomic-scale electrically induced
基金financially supported by the National Natural Science Foundation of China(61674050,62004056,and 61874158)the Project of Distinguished Young of Hebei Province(A2018201231)+7 种基金the Support Program for the Top Young Talents of Hebei Province(70280011807)the Hundred Persons Plan of Hebei Province(E2018050004 and E2018050003)the Supporting Plan for 100 Excellent Innovative Talents in Colleges and Universities of Hebei Province(SLRC2019018)the Special Project of Strategic Leading Science and Technology of Chinese Academy of Sciences(XDB44000000-7)the Special Support Funds for National High Level Talents(041500120001)Hebei Basic Research Special Key Project(F2021201045)the Science and Technology Project of Hebei Education Department(QN2020178 and QN2021026)Singapore Ministry of Education(Ac RF TIER 2-MOE2019-T2-2-075)。
基金supported by the National Natural Science Foundation of China(Nos.91963202,52072372,and 52232007).
文摘The rational design of electrodes is the key to achieving ultrahigh-power performance in electrochemical energy storage devices.Recently,we have constructed well-organized and integrated three-dimensional(3D)carbon tube(CT)grids(3D-CTGs)using a 3D porous anodic aluminum oxide template-assisted method as electrodes of electrical double-layer capacitors(EDLCs),showing excellent frequency response performance.The unique design warrants fast ion migration channels,excellent electronic conductivity,and good structural stability.This study achieved one of the highest carbon-based ultrahigh-power EDLCs with the 3D-CTG electrodes,resulting in ultrahigh power of 437 and 1708 W·cm−3 with aqueous and organic electrolytes,respectively.Capacitors constructed with these electrodes would have important application prospects in the ultrahigh-power output.The rational design and fabrication of the 3D-CTGs electrodes have demonstrated their capability to build capacitors with ultrahighpower performance and open up new possibilities for applications requiring high-power output.
基金supported by the National Natural Science Foundation of China(Grant Nos.62274135,52250060,and 62288102)supported by the Swedish Energy Agency Energimyndigheten(Nos.P2019-48758 and P2022-00394)+2 种基金the Göran Gustafsson Foundation for Research in Natural Sciences and Medicine and the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University(Faculty Grant SFO-Mat-LiU No.2009-00971)support from China Scholarship Council(No.202006210284)and Tsinghua Scholarship for short-term overseas graduate studiesby resources provided by the National Academic Infrastructure for Supercomputing in Sweden(NAISS)and the Swedish National Infrastructure for Computing(SNIC)at the National Supercomputer Centre(NSC)and the PDC Center for High Performance Computing partially funded by the Swedish Research Council through grant agreements no.2022-06725 and no.2018-05973.
文摘Although perovskite light-emitting diodes(PeLEDs)have seen unprecedented development in device efciency over the past decade,they sufer signifcantly from poor operational stability.This is especially true for blue PeLEDs,whose operational lifetime remains orders of magnitude behind their green and red counterparts.Here,we systematically investigate this efciency-stability discrepancy in a series of green-to blue-emitting PeLEDs based on mixed Br/Cl-perovskites.We fnd that chloride incorporation,while having only a limited impact on efciency,detrimentally afects device stability even in small amounts.Device lifetime drops exponentially with increasing Cl-content,accompanied by an increased rate of change in electrical properties during operation.We ascribe this phenomenon to an increased mobility of halogen ions in the mixed-halide lattice due to an increased chemically and structurally disordered landscape with reduced migration barriers.Our results indicate that the stability enhancement for PeLEDs might require diferent strategies from those used for improving efciency.