Phase segregation triggered by illumination is a typical stimulus response in wide-bandgap perovskites,and addressing it is vital for overcoming the stability bottleneck of perovskite devices by mitigating phase segre...Phase segregation triggered by illumination is a typical stimulus response in wide-bandgap perovskites,and addressing it is vital for overcoming the stability bottleneck of perovskite devices by mitigating phase segregation and implementing dynamic management.To tackle this,a dynamic covalent bond-mediated approach is proposed to deal with phase segregation in wide-bandgap perovskites.Results show that adding dynamic disulfide and diselenide bonds effectively suppresses phase segregation while keeping halogen homogeneity.A 1.77 eV wide-bandgap perovskite device attains a peak conversion efficiency of 21.02% and retains over 90% of its initial efficiency after 1200 h of continuous illumination at the maximum power point.A fabricated perovskite/perovskite tandem device reaches an optimal conversion efficiency of 28.45%.Incorporating dynamic covalent bonds presents a new strategy for mitigating phase segregation in wide-bandgap perovskites and is expected to drive further progress in this area.展开更多
Wide-bandgap mixed-halide perovskites,particularly CsPbIBr_(2),hold great promise for multi-junction solar cells due to their well-matched bandgap and all-inorganic material system.However,their inherent susceptibilit...Wide-bandgap mixed-halide perovskites,particularly CsPbIBr_(2),hold great promise for multi-junction solar cells due to their well-matched bandgap and all-inorganic material system.However,their inherent susceptibility to light-induced phase segregation(LIPS)limits efficiency and stability.In this work,we investigate the effect of three organic additives-4-cyclopentene-1,3-dione(CPD),maleimide(HPD),and 3,4-dibromo-1H-pyrrole-2,5(2H,5H)-dione(BrPD)-on LIPS in wide-bandgap CsPbIBr_(2)perovskite films.The additives form various chemical interactions,including coordination bonds,hydrogen bonds,and ionic bonds,with I^(-)and undercoordinated Pb^(2+)ions,among which BrPD has the strongest interaction.This interaction regulates crystallization and improves film morphology.The BrPD-modified films have the largest grain size and the highest light stability,suppressing LIPS,enhancing carrier transfer,and improving device performance.BrPD-modified CsPbIBr_(2)-based solar cells achieve a power conversion efficiency(PCE)of 11.34%,outperforming the control(8.96%)and other additives.Moreover,BrPDmodified devices show excellent stability,retaining 94%of their initial PCE after 60 min of continuous light exposure.This work highlights the potential of strategically selected organic additives to enhance the stability and performance of perovskite solar cells,offering valuable insights for the design of high-efficiency and long-lasting perovskite-based optoelectronic devices.展开更多
Inhomogeneous Pb/Sn elemental distribution and the resulted phase segregation in mixed Pb-Sn halide perovskites would result in energy disorder(band structure and phase distribution disorder),which greatly limits thei...Inhomogeneous Pb/Sn elemental distribution and the resulted phase segregation in mixed Pb-Sn halide perovskites would result in energy disorder(band structure and phase distribution disorder),which greatly limits their photovoltaic performance.Here,Pb S quantum dot has been synthesized and demonstrated as seeds for modulation crystallization dynamics of the mixed Pb-Sn inorganic perovskites,allowing an enhanced film quality and significantly suppressing phase segregation.With this additive power conversion efficiency of 8%and 6%is obtained under irradiation of full sunlight in planar and mesoporous structured solar cells in combination with CsPb_(0.5) Sn_(0.5)I_(2)Br inorganic perovskite,respectively.Our finding reveals exploring the actual Pb/Sn atoms location in perovskite structure and its influence on developing efficient and stable low-bandgap perovskite solar cells.展开更多
Proton exchange membranes （PEMs） are a key material for proton exchange membrane fuel cells （PEM-FCs）, Non-fluorinated hydrocarbon PEMs are low-cost alternatives to Nation, but limited by the low pro-ton conductiv...Proton exchange membranes （PEMs） are a key material for proton exchange membrane fuel cells （PEM-FCs）, Non-fluorinated hydrocarbon PEMs are low-cost alternatives to Nation, but limited by the low pro-ton conductivity, because of the weak phase segregation structure and narrow ion-transport channels.Various efforts have been taken to improve the performance of hydrocarbon PEMs, but mostly with com-plex methodologies. Here we demonstrate a simple, yet very efficient method to create phase segrega-tion structure inside a typical hydrocarbon PEM, sulfonated poly（ether ether ketone） （SPEEK）. By sim-ply adding appropriate amounts of water into the DMF solvent, the resulting SPEEK membrane exhibitswidened ion-transport channels, with the phase size of 2.7 nm, as indicated by both molecular dynamic（MD） simulations and transmission electron microscope （TEM） observations, and the proton conductivityis thus improved by 200%. These findings not only further our fundamental understanding of hydrocarbonPEMs, but are also valuable to the development of low-cost and practical fuel cell technologies.展开更多
Polycrystalline La0.67Ba0.33MnO3 bulk samples were annealed in flowing 95%Ar：5%H2 （AH） mixed gas at 973 K for different time respectively. The influence of the annealing time on the current-voltage properties was s...Polycrystalline La0.67Ba0.33MnO3 bulk samples were annealed in flowing 95%Ar：5%H2 （AH） mixed gas at 973 K for different time respectively. The influence of the annealing time on the current-voltage properties was systematically investigated. Linear current-voltage characteristics were observed in the as-prepared and the 10 h annealed samples, and nonlinear current-voltage characteristics was found in the 100 h annealed sample. At the same time, segregation of impurity phase and micro-cracks were found on the surfaces of the 100 h annealed samples, which was testified to be Ba ion impurity. Analysis showed that the changes of electronic properties were caused by barium ion im-purities and micro-cracks in the 100 h annealed sample.展开更多
Environmental stability is a major bottleneck of perovskite solar cells.Only a handful of studies are investigating the effect of moisture on the structural degradation of the absorber.They mostly rely on ex situ expe...Environmental stability is a major bottleneck of perovskite solar cells.Only a handful of studies are investigating the effect of moisture on the structural degradation of the absorber.They mostly rely on ex situ experiments and on completely degraded samples,which restrict the assessment on initial and final stage.By combining in situ X-ray diffraction under controlled 85%relative humidity,and live observations of the water-induced degradation using liquid-cell transmission electron microscopy,we reveal two competitive degradation paths leading on one hand to the decomposition of state-of-theart mixed cation/anion(Cs_(0.05)(MA_(0.17)FA_(0.83))_(0.95)Pb(Br_(0.17)I_(0.83))_(3)(CsMAFA)into PbI_(2) through a dissolution/recrystallization mechanism and,on the other hand,to a non-equilibrium phase segregation leading to CsPb_(2)Br_(5) and a Cesium-poor/iodide-rich Cs_(0.05)-x(MA_(0.17)FA_(0.83))_(0.95)Pb(Br_(0.17-2y)I_(0.83)+2y)_(3) perovskite.This degradation mechanism is corroborated at atomic-scale resolution through solid-state ^(1)H and ^(133)Cs NMR analysis.Exposure to moisture leads to a film containing important heterogeneities in terms of morphology,photoluminescence intensities,and lifetimes.Our results provide new insights and consensus that complex perovskite compositions,though very performant as champion devices,are comparatively metastable,a trait that limits the chances to achieve long-term stability.展开更多
Wide-bandgap(WB)mixed-halide perovskite solar cells(PSCs)play a crucial role in perovskite-based tandem solar cells(TSCs),enabling them to exceed the Shockley-Queisser limits of single-junction solar cells.Nonetheless...Wide-bandgap(WB)mixed-halide perovskite solar cells(PSCs)play a crucial role in perovskite-based tandem solar cells(TSCs),enabling them to exceed the Shockley-Queisser limits of single-junction solar cells.Nonetheless,the lack of stability in WB perovskite films due to photoinduced phase segregation undermines the stability of WB PSCs and their TSCs,thus impeding the commercialization of perovskite-based TSCs.Many efforts have been made to suppress photoinduced phase segregation in WB perovskite films and significant progresses have been obtained.In this review,we elaborate the mechanisms behind photoinduced phase segregation and its impact on the photovoltaic performance and stability of devices.The importance role of advanced characterization techniques in confirming the photoinduced phase segregation are comprehensively summarized.Beyond that,the effective strategies to alleviate photoinduced phase segregation in WB mixed halide PSCs are systematically assessed.Finally,the prospects for developing highly efficient and stable WB PSCs in tandem application are also presented.展开更多
Mixed cation strategy greatly benefits the enhancement of device performance and chemical stability.However,adverse impact also accompanies the mixed cation system simultaneously.It brings the compositional instabilit...Mixed cation strategy greatly benefits the enhancement of device performance and chemical stability.However,adverse impact also accompanies the mixed cation system simultaneously.It brings the compositional instability,wherein the homogeneous film is likely to segregate into multi-phases during the fabrication and ageing process,thus resulting in the efficiency reduction of perovskite solar cells(PSCs)devices.This review focuses on the cation induced phase segregation,and elucidates the segregation mechanisms from the perspectives of film formation and ageing process,respectively.Furthermore,the influence of cation segregation on device performance and operational stability are discussed.And based on these understandings,viable strategies are proposed for the design of phase-stable mixed composition halide perovskites and for suppressing segregation to benefit its development towards commercial applications.展开更多
Inorganic perovskitenanostructures have attracted considerable attention for their tunable band gaps and excellent optoelectronic properties.It is inevitable that phase segregation of halide perovskite usually occurs ...Inorganic perovskitenanostructures have attracted considerable attention for their tunable band gaps and excellent optoelectronic properties.It is inevitable that phase segregation of halide perovskite usually occurs in mixed-halide perovskites under a focused laser llumination,which caused by photo-induced halide-ion segregation.Here,we reported an uniform perovskite alloy nanowires via a chemical vapor deposition(CvD)method.Microstructural characterization reveals that these perovskite nanowires have independent linear morphology_with high-quality crystalline.Micro-photoluminescence(PL)spectra exhibit that these nanowire structures show a dual-wavelength emissions at 690 and 570 nm,respectively.Additionally,time-dependent PL intensity of the emission peak at 690 nm increased by the decrease of the emission peak at 570 nm under a focused laser llumination,indicating the formation of phase segregation at the excited positions.Moreover,based on these as-grown halide perovskite CsPbBr2.52lo.48 nanowires,a reasonably optical switch is designed and constructed.This optical switch may have potential applications in timed blasting system and time-delay circuit in the future.展开更多
Mixed halide perovskites with the ability to tune bandgaps exhibit attractive applications in tandem solar cells,building integrated photovoltaic and wavelength-tunable light-emitting devices.However,halide demixing u...Mixed halide perovskites with the ability to tune bandgaps exhibit attractive applications in tandem solar cells,building integrated photovoltaic and wavelength-tunable light-emitting devices.However,halide demixing under illumination or in the dark with a charge-carrier injection in both hybrid and inorganic perovskites results in bandgap instability and current-density-voltage(J-V)hysteresis,which can significantly hamper their application.Here,we demonstrate that halide segregation and J-V hysteresis in mixed halide inorganic CsPbIBr_(2)solar cells can be effectively mitigated by introducing an intermediate phase-enhanced Ostwald ripening through the control of the chemical composition in the CsPbIBr_(2)precursor solution.Excess amounts of either PbBr_(2)or CsI are incorporated into originally even molar amounts of PbBr_(2)and CsI precursor solutions.With the PbBr_(2)-excess,we observed an enlarged perovskite grain size,no detectable halide phase segregation at the grain boundaries nor the perovskite/TiO2 interface,an increased minority carrier lifetime,a reduced J-V hysteresis,and an improved solar-cell performance.However,different CsI:PbBr_(2)stoichiometric ratios were found to have different effects on the performance of the perovskite solar cell.The excessive lead phase is reactive with the dimethyl sulfoxide(DMSO)in the precursor solution to form the Pb(I,Br)2·DMSO complex and the quasi-twodimensional(2D)CsPb_(2)(I,Br)5,which are conducive to Ostwald maturation and defect extinction.Finally,the CsPbIBr_(2)solar cell with a PbBr_(2)-excess precursor composition reaches a power conversion efficiency(PCE)of 9.37%(stabilized PCE of 8.48%)and a maximum external quantum efficiency of over 90%.展开更多
In a recent online publication of Science,Professor Peter Strasser of the Technical University of Berlin,Germany,and his collaborators reported element-specific anisotropic growth of Pt and Ni in shaped Pt alloy synth...In a recent online publication of Science,Professor Peter Strasser of the Technical University of Berlin,Germany,and his collaborators reported element-specific anisotropic growth of Pt and Ni in shaped Pt alloy synthesis[1].They showed that the surface steps in the Pt3Ni concave hexapod alloy formed in the initial stage of the synthesis were crucial in the segregation of an M-rich(M=Ni,Co,展开更多
Thiocyanate-anion(SCN−)two-dimensional(2D)layered perovskite with internal stress-controlled nano phase segregation has been firstly demonstrated as a promising material system for luminescence applications.An interes...Thiocyanate-anion(SCN−)two-dimensional(2D)layered perovskite with internal stress-controlled nano phase segregation has been firstly demonstrated as a promising material system for luminescence applications.An interesting energy band structure is found as well as charge transfer process caused by nano phase segregation,which provide an alternative route to overcome the indirect-bandgap luminescence limit of SCN layered perovskites.It is revealed that,within the SCN layered framework,the segregated nano phases exist in a quantum well form,possessing much higher carrier localization and second-order radiative recombination abilities.With the help of internal stress modulation,these advantages can be significantly enhanced and finally contribute to high luminescence performances in visible-red regions.This work provides more potential opportunities for 2D layered perovskite materials in the future optoelectronic applications.展开更多
The segregation of Mg to phase interfaces in a nickel base superalloy IN 100 has been investi- gated using EPT(Electron Microprobe Technique).AES(Auger Electron Spectroscopy) and EDS analyses on thin TEM film.The resu...The segregation of Mg to phase interfaces in a nickel base superalloy IN 100 has been investi- gated using EPT(Electron Microprobe Technique).AES(Auger Electron Spectroscopy) and EDS analyses on thin TEM film.The results show that Mg segregates to the phase inter- faces of MC/γ and γ′/γ.The segregation concentration and layer thickness of Mg on MC/γ phase interface are larger than that on γ′/γ phase interface.Mg is not only a grain boundary segregation element,but also a phase interface segregation one.展开更多
Wide-bandgap(WBG)perovskites hold promising applicability in constructing high-efficiency tandem solar cells.However,WBG perovskites face serious light-induced phase segregation due to the presence of mixed halides,an...Wide-bandgap(WBG)perovskites hold promising applicability in constructing high-efficiency tandem solar cells.However,WBG perovskites face serious light-induced phase segregation due to the presence of mixed halides,and the segregation tendency becomes notably exacerbated with increasing bromine content.In addition,the mixed halide anions bring discrepant crystallization rates and thereby induce an inhomogeneous halide distribution within the WBG perovskite film.Here,we strategically propose a multidentate-ligand additive,N,N'-methylene-bis(2-amino-5-sulfhydryl-1,3,4-thiadiazole)(BL),into1.77 eV WBG perovskites to assist homogenized crystallization.The electron-donating groups in the BL molecule strongly coordinate with lead halides via Lewis acid-base complexation,while N-H groups anchor formamidinium(FA^(+))cations via hydrogen bonding,which delays crystallization and reduces the internal residual stress within the WBG perovskite films.Eventually,the optimized 1.77 eV WBG perovskite solar cells(PSCs)achieve a champion power conversion efficiency(PCE)of 19.24%.Most importantly,these WBG PSCs exhibit robust photostability,which maintain 88% of the initial PCE after 300 h of the maximum power point(MPP)tracking under one solar light illumination.This study demonstrates an effective route to solve the long-term stability of WBG perovskite and is of significance for the practical application of tandem solar cells in the future photovoltaic market.展开更多
The rapid rise in the power conversion efficiency(PCE)of CsPbBr_(2)I-based perovskite solar cells(PSCs),from 4.7%in 2016 to 11.08%in 2020,render it a promising material for use in photovoltaic devices.However,the phas...The rapid rise in the power conversion efficiency(PCE)of CsPbBr_(2)I-based perovskite solar cells(PSCs),from 4.7%in 2016 to 11.08%in 2020,render it a promising material for use in photovoltaic devices.However,the phase stability and current hysteresis caused by photo-induced phase segregation in CsPbBr_(2)I represent major obstacles to further improvements in the PCE for such devices.In this review,we describe the basic structure and optical properties of CsPbBr_(2)I,and systematically elaborate on the mechanism of the phase transition.We then discuss the strategies in progress to suppress phase transition in CsPbBr_(2)I,and their potential application in the photovoltaic field.Finally,challenges and application prospects for CsPbBr2I PSCs are summarized in the final section of this article.展开更多
Wide-bandgap(>1.7 eV)perovskites suffer from severe light-induced phase segregation due to high bromine content,causing irreversible damage to devices stability.However,the strategies of suppressing photoinduced ph...Wide-bandgap(>1.7 eV)perovskites suffer from severe light-induced phase segregation due to high bromine content,causing irreversible damage to devices stability.However,the strategies of suppressing photoinduced phase segregation and related mechanisms have not been fully disclosed.Here,we report a new passivation agent 4-aminotetrahydrothiopyran hydrochloride(4-ATpHCl)with multifunctional groups for the interface treatment of a 1.77-eV wide-bandgap perovskite film.4-ATpH^(+)impeded halogen ion migration by anchoring on the perovskite surface,leading to the inhibition of phase segregation and thus the passivation of defects,which is ascribed to the interaction of 4-ATpH^(+)with perovskite and the formation of low-dimensional perovskites.Finally,the champion device achieved an efficiency of 19.32%with an open-circuit voltage(V_(OC))of 1.314 V and a fill factor of 83.32%.Moreover,4-ATpHCl modified device exhibited significant improved stability as compared with control one.The target device maintained 80%of its initial efficiency after 519 h of maximum power output(MPP)tracking under 1 sun illumination,however,the control device showed a rapid decrease in efficiency after 267 h.Finally,an efficiency of 27.38%of the champion 4-terminal all-perovskite tandem solar cell was achieved by mechanically stacking this wide-bandgap top subcell with a 1.25-eV low-bandgap perovskite bottom subcell.展开更多
Janus particles,in which two distinct compositions are integrated,have attracted considerable interest for their potential multi-functionalities and synergistic effects.Although seed-mediated growth appears to be a su...Janus particles,in which two distinct compositions are integrated,have attracted considerable interest for their potential multi-functionalities and synergistic effects.Although seed-mediated growth appears to be a suitable strategy that meets the stringent specifications for obtaining Janus particles,it is inapplicable to guide the growth of two crystalline components with different crystal structures.Herein,the formation of Janus particles via phase segregation is proposed.As proof-of-concept,promising photon conversion materials,ScF_(3)and lanthanide(Ln)fluorides,with great differences in structure,were chosen to build a series of Janus particles.Interestingly,using heavy(Lu,Yb,Dy and Tb)and light(Pr,Nd,Sm,Eu and Gd)lanthanides,ScF_(3)-LiLnF_(4)and ScF_(3)-LnF_(3)were formed,respectively.Time-dependent reaction studies indicate that phase segregation paves the way for the formation of these Janus nanoparticles(NPs),and this speculation is further confirmed by in situ transmission electron microscopy observations.These investigations provide new insights for the synthesis of heterostructured materials.展开更多
L1_(0)-FePt nanoparticles(NPs)are urgently anticipated because of their promising applications.However,the preparation of the NPs with both of high ordering degree and super-fine size is still a challenge.Inspired by ...L1_(0)-FePt nanoparticles(NPs)are urgently anticipated because of their promising applications.However,the preparation of the NPs with both of high ordering degree and super-fine size is still a challenge.Inspired by recent studies on the effect of vacancy defects on structural ordering,we proposed an intentional vacancy defect design strategy for directly synthesizing highly ordered FePt NPs.In the present work,we used the first-principle calculations to investigate the influence of doping typical elements(Cu,Ag,and Pb)on the vacancy formation energy(E_(vac))of FePt NPs.The vacancy defects were effectively formed by introducing elements of larger atomic radii and higher propensity for segregation into the FePt lattice,facilitating the diffusion of Fe and Pt atoms.The Pb doping showed remarkable efficacy in promoting the ordering transition.Experimentally,wet-chemical synthesis confirmed the success of the proposed strategy in achieving highly ordered L1_(0)-FePt NPs with exceptional magnetic properties and super-fine size(ordering degree of 0.896,impressive coercivity of 21.74 kOe,and small particle size of 9.02 nm).Additionally,we have deduced a diffusion model elucidating the formation process of the ordered FePt NPs,focusing on the migration of Pb atoms from the center to the surface of the particles.This migration is demonstrated to generate more vacancies and promote the transition to the ordered L1_(0)-FePt phase.The findings of this research offer valuable insights into synthesizing highly ordered and ultrafine L1_(0)-type nanomaterials.展开更多
This paper describes the design of a FeWO_(x)-based oxygen carrier for the chemical partial oxidation of methane(CLPOM).Thermodynamic screening and kinetic analyses both forecast the FeWO_(x)-based oxygen carrier as a...This paper describes the design of a FeWO_(x)-based oxygen carrier for the chemical partial oxidation of methane(CLPOM).Thermodynamic screening and kinetic analyses both forecast the FeWO_(x)-based oxygen carrier as a promising candidate for the production of syngas.The total methane conversion and syngas yield can be dramatically increased with this catalyst compared to the case with the unmodified WO_(3)/SiO_(2),thereby enabling CLPOM with 62%methane conversion,93%CO gas-phase selectivity,94%H2 selectivity,and a 2.4 H_(2)/CO ratio.The catalyst has the advantages of high availability of lattice oxygen to oxidize carbonaceous intermediates in time,together with the formation of an Fe-W alloy to promote the surface reaction.Consequently,it demonstrates excellent catalytic performance with no catalyst deactivation at 900℃ and 1 atm.The excellent structural stability plays an essential role in CLPOM.As revealed via XPS and ICP,the phase segregation has not been observed due to the strong interaction between Fe and W,which resulted in the formation of the Fe-W alloy during the reduction processes and the match between the ion oxidation rates of the Fe and W ions in the oxidation stage.The results provide fundamental information on the reaction mechanism of FeWO_(x)/SiO_(2),and present it as a promising candidate for CLPOM.展开更多
基金the financial support from the National Key R&D Program of China(2023YFE0111500)the National Nature Science Foundation of China(52103237,52321006,T2394480,T2394484)the Key Research Project Plan of Higher Education Institutions in Henan Province,China(26A150044)。
文摘Phase segregation triggered by illumination is a typical stimulus response in wide-bandgap perovskites,and addressing it is vital for overcoming the stability bottleneck of perovskite devices by mitigating phase segregation and implementing dynamic management.To tackle this,a dynamic covalent bond-mediated approach is proposed to deal with phase segregation in wide-bandgap perovskites.Results show that adding dynamic disulfide and diselenide bonds effectively suppresses phase segregation while keeping halogen homogeneity.A 1.77 eV wide-bandgap perovskite device attains a peak conversion efficiency of 21.02% and retains over 90% of its initial efficiency after 1200 h of continuous illumination at the maximum power point.A fabricated perovskite/perovskite tandem device reaches an optimal conversion efficiency of 28.45%.Incorporating dynamic covalent bonds presents a new strategy for mitigating phase segregation in wide-bandgap perovskites and is expected to drive further progress in this area.
基金supported financially by the National Key R&D Program of China(Grant No.2023YFE0111500)the National Natural Science Foundation of China(Grant Nos.52321006,T2394480,T2394484,22109143,22475196,22479131)+11 种基金the Research Grants Council of Hong Kong(CRF C4005-22YRGC Senior Research Fellowship Scheme(SRFS2223-5S01))the Joint Fund for Provincial Science and Technology R&D Program of Henan(grant no.242301420051)the Opening Project of the State Key Laboratory of Advanced Technology for Float Glass(grant no.2022KF04)the China Postdoctoral Innovative Talent Support Program(grant no.BX2021271)the China Postdoctoral Science Foundation(grant no.2022M712851)the Graduate Education Reform Project of Henan Province(Grant No.2023SJGLX136Y)the Key R&D Special Program of Henan Province(Grant No.241111242000)the Program for Science&Technology Innovation Talents in Universities of Henan Province(Grant No.25HASTIT005)the Training Plan for Young Backbone Teachers of Zhengzhou University(Grant No.2023ZDGGJS017)the Joint Research Project of Puyang ShengtongJuyuan New Materials Co.Ltd.(Grant No.20230128A)。
文摘Wide-bandgap mixed-halide perovskites,particularly CsPbIBr_(2),hold great promise for multi-junction solar cells due to their well-matched bandgap and all-inorganic material system.However,their inherent susceptibility to light-induced phase segregation(LIPS)limits efficiency and stability.In this work,we investigate the effect of three organic additives-4-cyclopentene-1,3-dione(CPD),maleimide(HPD),and 3,4-dibromo-1H-pyrrole-2,5(2H,5H)-dione(BrPD)-on LIPS in wide-bandgap CsPbIBr_(2)perovskite films.The additives form various chemical interactions,including coordination bonds,hydrogen bonds,and ionic bonds,with I^(-)and undercoordinated Pb^(2+)ions,among which BrPD has the strongest interaction.This interaction regulates crystallization and improves film morphology.The BrPD-modified films have the largest grain size and the highest light stability,suppressing LIPS,enhancing carrier transfer,and improving device performance.BrPD-modified CsPbIBr_(2)-based solar cells achieve a power conversion efficiency(PCE)of 11.34%,outperforming the control(8.96%)and other additives.Moreover,BrPDmodified devices show excellent stability,retaining 94%of their initial PCE after 60 min of continuous light exposure.This work highlights the potential of strategically selected organic additives to enhance the stability and performance of perovskite solar cells,offering valuable insights for the design of high-efficiency and long-lasting perovskite-based optoelectronic devices.
基金Financial support from the National Key Research and Development Program of China (2019YFE0101300, 2018YFB1502900)the National Natural Science Foundation of China (No. 21975088)+1 种基金the National Natural Science Foundation of China Major International (Regional) Joint Research Project (No. 51961165106)the double first-class research funding of China-EU Institute for Clean and Renewable Energy (3011187029)。
文摘Inhomogeneous Pb/Sn elemental distribution and the resulted phase segregation in mixed Pb-Sn halide perovskites would result in energy disorder(band structure and phase distribution disorder),which greatly limits their photovoltaic performance.Here,Pb S quantum dot has been synthesized and demonstrated as seeds for modulation crystallization dynamics of the mixed Pb-Sn inorganic perovskites,allowing an enhanced film quality and significantly suppressing phase segregation.With this additive power conversion efficiency of 8%and 6%is obtained under irradiation of full sunlight in planar and mesoporous structured solar cells in combination with CsPb_(0.5) Sn_(0.5)I_(2)Br inorganic perovskite,respectively.Our finding reveals exploring the actual Pb/Sn atoms location in perovskite structure and its influence on developing efficient and stable low-bandgap perovskite solar cells.
基金financially supported by the National Key Research and Development Program of China (2016YFB0101203)the National Natural Science Foundation of China (91545205,21633008)
文摘Proton exchange membranes （PEMs） are a key material for proton exchange membrane fuel cells （PEM-FCs）, Non-fluorinated hydrocarbon PEMs are low-cost alternatives to Nation, but limited by the low pro-ton conductivity, because of the weak phase segregation structure and narrow ion-transport channels.Various efforts have been taken to improve the performance of hydrocarbon PEMs, but mostly with com-plex methodologies. Here we demonstrate a simple, yet very efficient method to create phase segrega-tion structure inside a typical hydrocarbon PEM, sulfonated poly（ether ether ketone） （SPEEK）. By sim-ply adding appropriate amounts of water into the DMF solvent, the resulting SPEEK membrane exhibitswidened ion-transport channels, with the phase size of 2.7 nm, as indicated by both molecular dynamic（MD） simulations and transmission electron microscope （TEM） observations, and the proton conductivityis thus improved by 200%. These findings not only further our fundamental understanding of hydrocarbonPEMs, but are also valuable to the development of low-cost and practical fuel cell technologies.
基金supported by the National Natural Science Foundation of China (10975103)
文摘Polycrystalline La0.67Ba0.33MnO3 bulk samples were annealed in flowing 95%Ar：5%H2 （AH） mixed gas at 973 K for different time respectively. The influence of the annealing time on the current-voltage properties was systematically investigated. Linear current-voltage characteristics were observed in the as-prepared and the 10 h annealed samples, and nonlinear current-voltage characteristics was found in the 100 h annealed sample. At the same time, segregation of impurity phase and micro-cracks were found on the surfaces of the 100 h annealed samples, which was testified to be Ba ion impurity. Analysis showed that the changes of electronic properties were caused by barium ion im-purities and micro-cracks in the 100 h annealed sample.
基金financial support from Region Hauts-de-France,FEDER,and Electricité de France(EDF)through PEROVSTAB programfinancial support from the IR-RMN-THC FR-3050 CNRS France for conducting solid-state NMR measurements.P.R.and G.N.M.R+1 种基金financial support from University of Lille and région Hauts-de-France.F.S“IMPRESSIVE”project which received funding from the European Union’s Horizon 2020 Research and Innovation Program under grant agreement number 826013.
文摘Environmental stability is a major bottleneck of perovskite solar cells.Only a handful of studies are investigating the effect of moisture on the structural degradation of the absorber.They mostly rely on ex situ experiments and on completely degraded samples,which restrict the assessment on initial and final stage.By combining in situ X-ray diffraction under controlled 85%relative humidity,and live observations of the water-induced degradation using liquid-cell transmission electron microscopy,we reveal two competitive degradation paths leading on one hand to the decomposition of state-of-theart mixed cation/anion(Cs_(0.05)(MA_(0.17)FA_(0.83))_(0.95)Pb(Br_(0.17)I_(0.83))_(3)(CsMAFA)into PbI_(2) through a dissolution/recrystallization mechanism and,on the other hand,to a non-equilibrium phase segregation leading to CsPb_(2)Br_(5) and a Cesium-poor/iodide-rich Cs_(0.05)-x(MA_(0.17)FA_(0.83))_(0.95)Pb(Br_(0.17-2y)I_(0.83)+2y)_(3) perovskite.This degradation mechanism is corroborated at atomic-scale resolution through solid-state ^(1)H and ^(133)Cs NMR analysis.Exposure to moisture leads to a film containing important heterogeneities in terms of morphology,photoluminescence intensities,and lifetimes.Our results provide new insights and consensus that complex perovskite compositions,though very performant as champion devices,are comparatively metastable,a trait that limits the chances to achieve long-term stability.
基金the National Natural Science Foundation of China(Grant No.62274018)the Xinjiang Construction Corps Key Areas of Science and Technology Research Project(Grant No.2023AB029)the Key Project of Chongqing Overseas Students Returning to China Entrepreneurship and Innovation Support Plan(Grant No.cx2023006).
文摘Wide-bandgap(WB)mixed-halide perovskite solar cells(PSCs)play a crucial role in perovskite-based tandem solar cells(TSCs),enabling them to exceed the Shockley-Queisser limits of single-junction solar cells.Nonetheless,the lack of stability in WB perovskite films due to photoinduced phase segregation undermines the stability of WB PSCs and their TSCs,thus impeding the commercialization of perovskite-based TSCs.Many efforts have been made to suppress photoinduced phase segregation in WB perovskite films and significant progresses have been obtained.In this review,we elaborate the mechanisms behind photoinduced phase segregation and its impact on the photovoltaic performance and stability of devices.The importance role of advanced characterization techniques in confirming the photoinduced phase segregation are comprehensively summarized.Beyond that,the effective strategies to alleviate photoinduced phase segregation in WB mixed halide PSCs are systematically assessed.Finally,the prospects for developing highly efficient and stable WB PSCs in tandem application are also presented.
基金National Natural Science Foundation of China(22109057,21805010,21975028,52172182,22011540377,22005035)Beijing Municipal Science and Technology Project(Z181100005118002)+2 种基金Beijing Municipal Natural Science Foundation(JQ19008)the China Postdoctoral Science Foundation(Grant No.2020TQ0043,2020M680012)Research Foundation of Jiangxi Educational Committee(GJJ200836).
文摘Mixed cation strategy greatly benefits the enhancement of device performance and chemical stability.However,adverse impact also accompanies the mixed cation system simultaneously.It brings the compositional instability,wherein the homogeneous film is likely to segregate into multi-phases during the fabrication and ageing process,thus resulting in the efficiency reduction of perovskite solar cells(PSCs)devices.This review focuses on the cation induced phase segregation,and elucidates the segregation mechanisms from the perspectives of film formation and ageing process,respectively.Furthermore,the influence of cation segregation on device performance and operational stability are discussed.And based on these understandings,viable strategies are proposed for the design of phase-stable mixed composition halide perovskites and for suppressing segregation to benefit its development towards commercial applications.
基金The authors are grateful to the National Natural Science Foundation of China(No.52373246)the Fundamental Research Program of Shanxi Provinces(No.20210302123128)the National Key Research and Development Program of China(No.2022YFA1404201)for financial support.
文摘Inorganic perovskitenanostructures have attracted considerable attention for their tunable band gaps and excellent optoelectronic properties.It is inevitable that phase segregation of halide perovskite usually occurs in mixed-halide perovskites under a focused laser llumination,which caused by photo-induced halide-ion segregation.Here,we reported an uniform perovskite alloy nanowires via a chemical vapor deposition(CvD)method.Microstructural characterization reveals that these perovskite nanowires have independent linear morphology_with high-quality crystalline.Micro-photoluminescence(PL)spectra exhibit that these nanowire structures show a dual-wavelength emissions at 690 and 570 nm,respectively.Additionally,time-dependent PL intensity of the emission peak at 690 nm increased by the decrease of the emission peak at 570 nm under a focused laser llumination,indicating the formation of phase segregation at the excited positions.Moreover,based on these as-grown halide perovskite CsPbBr2.52lo.48 nanowires,a reasonably optical switch is designed and constructed.This optical switch may have potential applications in timed blasting system and time-delay circuit in the future.
基金the National Natural Science Foundation of China(51802241 and 91963209)the Fundamental Research Funds for the Central Universities(WUT:2019IVB055 and 2019IVA066)+1 种基金ARC Discovery Grant DP150104483,ARC Centre of Excellence in Exciton Science(CE170100026)the Australian Government through the Australian Renewable Energy Agency(ARENA).
文摘Mixed halide perovskites with the ability to tune bandgaps exhibit attractive applications in tandem solar cells,building integrated photovoltaic and wavelength-tunable light-emitting devices.However,halide demixing under illumination or in the dark with a charge-carrier injection in both hybrid and inorganic perovskites results in bandgap instability and current-density-voltage(J-V)hysteresis,which can significantly hamper their application.Here,we demonstrate that halide segregation and J-V hysteresis in mixed halide inorganic CsPbIBr_(2)solar cells can be effectively mitigated by introducing an intermediate phase-enhanced Ostwald ripening through the control of the chemical composition in the CsPbIBr_(2)precursor solution.Excess amounts of either PbBr_(2)or CsI are incorporated into originally even molar amounts of PbBr_(2)and CsI precursor solutions.With the PbBr_(2)-excess,we observed an enlarged perovskite grain size,no detectable halide phase segregation at the grain boundaries nor the perovskite/TiO2 interface,an increased minority carrier lifetime,a reduced J-V hysteresis,and an improved solar-cell performance.However,different CsI:PbBr_(2)stoichiometric ratios were found to have different effects on the performance of the perovskite solar cell.The excessive lead phase is reactive with the dimethyl sulfoxide(DMSO)in the precursor solution to form the Pb(I,Br)2·DMSO complex and the quasi-twodimensional(2D)CsPb_(2)(I,Br)5,which are conducive to Ostwald maturation and defect extinction.Finally,the CsPbIBr_(2)solar cell with a PbBr_(2)-excess precursor composition reaches a power conversion efficiency(PCE)of 9.37%(stabilized PCE of 8.48%)and a maximum external quantum efficiency of over 90%.
文摘In a recent online publication of Science,Professor Peter Strasser of the Technical University of Berlin,Germany,and his collaborators reported element-specific anisotropic growth of Pt and Ni in shaped Pt alloy synthesis[1].They showed that the surface steps in the Pt3Ni concave hexapod alloy formed in the initial stage of the synthesis were crucial in the segregation of an M-rich(M=Ni,Co,
基金supported by the National Natural Science Foundation of China(Nos.52102332,11874402,51872321,52172260,52072402,and 51627803)Beijing Natural Science Foundation(No.2222082)the Ministry of Science and Technology of the People’s Republic of China(No.2021YFB3800103)。
文摘Thiocyanate-anion(SCN−)two-dimensional(2D)layered perovskite with internal stress-controlled nano phase segregation has been firstly demonstrated as a promising material system for luminescence applications.An interesting energy band structure is found as well as charge transfer process caused by nano phase segregation,which provide an alternative route to overcome the indirect-bandgap luminescence limit of SCN layered perovskites.It is revealed that,within the SCN layered framework,the segregated nano phases exist in a quantum well form,possessing much higher carrier localization and second-order radiative recombination abilities.With the help of internal stress modulation,these advantages can be significantly enhanced and finally contribute to high luminescence performances in visible-red regions.This work provides more potential opportunities for 2D layered perovskite materials in the future optoelectronic applications.
文摘The segregation of Mg to phase interfaces in a nickel base superalloy IN 100 has been investi- gated using EPT(Electron Microprobe Technique).AES(Auger Electron Spectroscopy) and EDS analyses on thin TEM film.The results show that Mg segregates to the phase inter- faces of MC/γ and γ′/γ.The segregation concentration and layer thickness of Mg on MC/γ phase interface are larger than that on γ′/γ phase interface.Mg is not only a grain boundary segregation element,but also a phase interface segregation one.
基金supported by the National Natural Science Foundation of China(52202178)the Natural Science Foundation of Shanghai(22ZR1426300)。
文摘Wide-bandgap(WBG)perovskites hold promising applicability in constructing high-efficiency tandem solar cells.However,WBG perovskites face serious light-induced phase segregation due to the presence of mixed halides,and the segregation tendency becomes notably exacerbated with increasing bromine content.In addition,the mixed halide anions bring discrepant crystallization rates and thereby induce an inhomogeneous halide distribution within the WBG perovskite film.Here,we strategically propose a multidentate-ligand additive,N,N'-methylene-bis(2-amino-5-sulfhydryl-1,3,4-thiadiazole)(BL),into1.77 eV WBG perovskites to assist homogenized crystallization.The electron-donating groups in the BL molecule strongly coordinate with lead halides via Lewis acid-base complexation,while N-H groups anchor formamidinium(FA^(+))cations via hydrogen bonding,which delays crystallization and reduces the internal residual stress within the WBG perovskite films.Eventually,the optimized 1.77 eV WBG perovskite solar cells(PSCs)achieve a champion power conversion efficiency(PCE)of 19.24%.Most importantly,these WBG PSCs exhibit robust photostability,which maintain 88% of the initial PCE after 300 h of the maximum power point(MPP)tracking under one solar light illumination.This study demonstrates an effective route to solve the long-term stability of WBG perovskite and is of significance for the practical application of tandem solar cells in the future photovoltaic market.
基金the National Natural Science Foundation of China(52073131,51902148,61704099,61874166,U1832149,51801088 and 51802024)the Natural Science Foundation of Gansu Province(20JR5RA227,20JR5RA217,20JR5RA278)the Fundamental Research Funds for the Central Universities(lzujbky-2020-61,lzujbky-2019-88 and lzujbky-2020-kb06).
文摘The rapid rise in the power conversion efficiency(PCE)of CsPbBr_(2)I-based perovskite solar cells(PSCs),from 4.7%in 2016 to 11.08%in 2020,render it a promising material for use in photovoltaic devices.However,the phase stability and current hysteresis caused by photo-induced phase segregation in CsPbBr_(2)I represent major obstacles to further improvements in the PCE for such devices.In this review,we describe the basic structure and optical properties of CsPbBr_(2)I,and systematically elaborate on the mechanism of the phase transition.We then discuss the strategies in progress to suppress phase transition in CsPbBr_(2)I,and their potential application in the photovoltaic field.Finally,challenges and application prospects for CsPbBr2I PSCs are summarized in the final section of this article.
基金financially supported by the National Key R&D Program of China (2022YFB4200304)the National Natural Science Foundation of China (52303347)+3 种基金the Fundamental Research Funds for the Central Universities (YJ2021157)the Engineering Featured Team Fund of Sichuan University (2020SCUNG102)open foundation of Guangxi Key Laboratory of Processing for Non-Ferrous Metals and Featured Materials, Guangxi University (2022GXYSOF05)the support from the National Natural Science Foundation of China (E30853YM19)
文摘Wide-bandgap(>1.7 eV)perovskites suffer from severe light-induced phase segregation due to high bromine content,causing irreversible damage to devices stability.However,the strategies of suppressing photoinduced phase segregation and related mechanisms have not been fully disclosed.Here,we report a new passivation agent 4-aminotetrahydrothiopyran hydrochloride(4-ATpHCl)with multifunctional groups for the interface treatment of a 1.77-eV wide-bandgap perovskite film.4-ATpH^(+)impeded halogen ion migration by anchoring on the perovskite surface,leading to the inhibition of phase segregation and thus the passivation of defects,which is ascribed to the interaction of 4-ATpH^(+)with perovskite and the formation of low-dimensional perovskites.Finally,the champion device achieved an efficiency of 19.32%with an open-circuit voltage(V_(OC))of 1.314 V and a fill factor of 83.32%.Moreover,4-ATpHCl modified device exhibited significant improved stability as compared with control one.The target device maintained 80%of its initial efficiency after 519 h of maximum power output(MPP)tracking under 1 sun illumination,however,the control device showed a rapid decrease in efficiency after 267 h.Finally,an efficiency of 27.38%of the champion 4-terminal all-perovskite tandem solar cell was achieved by mechanically stacking this wide-bandgap top subcell with a 1.25-eV low-bandgap perovskite bottom subcell.
基金supported by NSFC(No.21425101,21371011,21331001,21590791)MOST of China(2014CB643800,2017YFA0205101).
文摘Janus particles,in which two distinct compositions are integrated,have attracted considerable interest for their potential multi-functionalities and synergistic effects.Although seed-mediated growth appears to be a suitable strategy that meets the stringent specifications for obtaining Janus particles,it is inapplicable to guide the growth of two crystalline components with different crystal structures.Herein,the formation of Janus particles via phase segregation is proposed.As proof-of-concept,promising photon conversion materials,ScF_(3)and lanthanide(Ln)fluorides,with great differences in structure,were chosen to build a series of Janus particles.Interestingly,using heavy(Lu,Yb,Dy and Tb)and light(Pr,Nd,Sm,Eu and Gd)lanthanides,ScF_(3)-LiLnF_(4)and ScF_(3)-LnF_(3)were formed,respectively.Time-dependent reaction studies indicate that phase segregation paves the way for the formation of these Janus nanoparticles(NPs),and this speculation is further confirmed by in situ transmission electron microscopy observations.These investigations provide new insights for the synthesis of heterostructured materials.
基金Financial supports from The National Natural Science Foundation of China(Nos.51625402,51790483,51801069 and U19A2084)are greatly acknowledgedPartial financial support came from The Science and Technology Devel-opment Program of Jilin Province(Nos.20190901010JC,20190103003JH,20200401025GX and 20200201002JC)The Changjiang Scholars Program(T2017035).
基金supported by the National Key Research and Development Program of China(Nos.2020YFA0907300 and 2021YFB3501404)the National Natural Science Foundation of China(Nos.52301234,52371179,and 52071070)+1 种基金the Doctoral Start-up Foundation of Liaoning Province(No.2023-BS-059)the Fundamental Research Funds for the Central Universities(No.N2309002).
文摘L1_(0)-FePt nanoparticles(NPs)are urgently anticipated because of their promising applications.However,the preparation of the NPs with both of high ordering degree and super-fine size is still a challenge.Inspired by recent studies on the effect of vacancy defects on structural ordering,we proposed an intentional vacancy defect design strategy for directly synthesizing highly ordered FePt NPs.In the present work,we used the first-principle calculations to investigate the influence of doping typical elements(Cu,Ag,and Pb)on the vacancy formation energy(E_(vac))of FePt NPs.The vacancy defects were effectively formed by introducing elements of larger atomic radii and higher propensity for segregation into the FePt lattice,facilitating the diffusion of Fe and Pt atoms.The Pb doping showed remarkable efficacy in promoting the ordering transition.Experimentally,wet-chemical synthesis confirmed the success of the proposed strategy in achieving highly ordered L1_(0)-FePt NPs with exceptional magnetic properties and super-fine size(ordering degree of 0.896,impressive coercivity of 21.74 kOe,and small particle size of 9.02 nm).Additionally,we have deduced a diffusion model elucidating the formation process of the ordered FePt NPs,focusing on the migration of Pb atoms from the center to the surface of the particles.This migration is demonstrated to generate more vacancies and promote the transition to the ordered L1_(0)-FePt phase.The findings of this research offer valuable insights into synthesizing highly ordered and ultrafine L1_(0)-type nanomaterials.
文摘This paper describes the design of a FeWO_(x)-based oxygen carrier for the chemical partial oxidation of methane(CLPOM).Thermodynamic screening and kinetic analyses both forecast the FeWO_(x)-based oxygen carrier as a promising candidate for the production of syngas.The total methane conversion and syngas yield can be dramatically increased with this catalyst compared to the case with the unmodified WO_(3)/SiO_(2),thereby enabling CLPOM with 62%methane conversion,93%CO gas-phase selectivity,94%H2 selectivity,and a 2.4 H_(2)/CO ratio.The catalyst has the advantages of high availability of lattice oxygen to oxidize carbonaceous intermediates in time,together with the formation of an Fe-W alloy to promote the surface reaction.Consequently,it demonstrates excellent catalytic performance with no catalyst deactivation at 900℃ and 1 atm.The excellent structural stability plays an essential role in CLPOM.As revealed via XPS and ICP,the phase segregation has not been observed due to the strong interaction between Fe and W,which resulted in the formation of the Fe-W alloy during the reduction processes and the match between the ion oxidation rates of the Fe and W ions in the oxidation stage.The results provide fundamental information on the reaction mechanism of FeWO_(x)/SiO_(2),and present it as a promising candidate for CLPOM.
