Precise control over the charge carrier dynamics throughout the device can result in outstanding performance of perovskite solar cells(PSCs).Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is the mo...Precise control over the charge carrier dynamics throughout the device can result in outstanding performance of perovskite solar cells(PSCs).Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is the most actively studied hole transport material in p-i-n structured PSCs.However,charge transport in the PEDOT:PSS is limited and inefficient because of its low conductivity with the presence of the weak ionic conductor PSS.In addition,morphology of the underlying PEDOT:PSS layer in PSCs plays a crucial role in determining the optoelectronic quality of the active perovskite absorber layer.This work is focused on realization of a non-wetting conductive surface of hole transport layer suitable for the growth of larger perovskite crystalline domains.This is accomplished by employing a facile solventengineered(ethylene glycol and methanol)approach resulting in removal of the predominant PSS in PEDOT:PSS.The consequence of acquiring larger perovskite crystalline domains was observed in the charge carrier dynamics studies,with the achievement of higher charge carrier lifetime,lower charge transport time and lower transfer impedance in the solvent-engineered PEDOT:PSS-based PSCs.Use of this solventengineered treatment for the fabrication of MAPbI3 PSCs greatly increased the device stability witnessing a power conversion efficiency of 18.18%,which corresponds to^37%improvement compared to the untreated PEDOT:PSS based devices.展开更多
Transition-metal phosphides(TMPs)-based hybrid structure have received considerable attention for efficient sodium storage owing to their high capacity and decent reversibility.However,the volume expansion&the poo...Transition-metal phosphides(TMPs)-based hybrid structure have received considerable attention for efficient sodium storage owing to their high capacity and decent reversibility.However,the volume expansion&the poor electronic conductivity of TMPs,the poor-rate capability,and fast capacity decay greatly hinder its practical application.To address these issues,a low-cost and facile strategy for the synthesis of Ni,N-codoped graphitized carbon(C)and cobalt phosphide(CoP)embedded in carbon fiber(Ni-CoP@CN⊂CF)as self-supporting anode material is demonstrated for the first time.The graphitized carbon and carbon fiber improve the electrical conductivity and inhibit the volume expansion issues.In addition to that,the microporous structure,and ultrasmall sized Ni-CoP offer a high surface area for electrolyte wettability,short Na-ion diffusion path and fast charge transport kinetics.As a result,outstanding electrochemical performance with an average capacity decay of 0.04%cycle^(−1)at 2000 mA g^(−1),an excellent rate capability of 270 mAh g^(−1)@2000 mA g^(−1)and a high energy density of~231.1 Wh kg^(−1)is achieved with binder-free self-supporting anode material.This work shows a potential for designing binder-free and high energy density sodium-ion batteries.展开更多
While neutral aqueous metal batteries,featuring cost-effectiveness and non-flammability,hold significant potential for large-scale energy storage,their practical application is hampered by the limited specific capacit...While neutral aqueous metal batteries,featuring cost-effectiveness and non-flammability,hold significant potential for large-scale energy storage,their practical application is hampered by the limited specific capacity of cathode materials(<500 mAh g^(-1)).Herein,capacity-oriented CoS2 and rate-optimized Co9S8 cathodes are developed based on the aqueous copper ion system.The charge-storage mechanism is sys-tematically investigated through a series of ex-situ tests and density functional theory calculations,fo-cusing on the reversible transitions of Co9S8→Cu7S4→Cu9S5/Cu1.8S and CoS2→Cu7S4→Cu2S,which are associated with the redox reactions of Cu^(2+)/Cu^(+)‖Co^(2+)/Co and Cu^(2+)/Cu^(+)‖S22-/S2-,respectively.The elec-trochemical results show that CoS2 can exhibit a superior capacity of 619 mAh g^(-1) at 1 A g^(-1) after 400 cycles,while Co9S8 maintains an outstanding rate performance of 497 mAh g^(-1) at 10 A g^(-1)(the retention rate is 95%compared to 521 mAh g1 at 1 A g^(-1)).As a proof of concept,an advanced CoS2//Zn hybrid aqueous battery demonstrates a working voltage of 1.20 V and a specific energy of 663 Wh kgcathode-1.This work provides an alternative direction for developing sulfide cathodes in energetic aqueous metal batteries.展开更多
In this work,grain boundary(GB)potential barrier(ΔφGB),dopant density(Pnet),and filled trap state density(PGB,trap)were manipulated at the nanoscale by exposing the fabricated perovskite films to various relative hu...In this work,grain boundary(GB)potential barrier(ΔφGB),dopant density(Pnet),and filled trap state density(PGB,trap)were manipulated at the nanoscale by exposing the fabricated perovskite films to various relative humidity(RH)environments.Spatial mapping of surface potential in the perovskite film revealed higher positive potential at GBs than inside the grains.The averageΔφGB,Pnet,and PGB,trap in the perovskite films decreased from 0%RH to 25%RH exposure,but increased when the RH increased to 35%RH and 45%RH.This clearly indicated that perovskite solar cells fabricated at 25%RH led to the lowest average GB potential,smallest dopant density,and least filled trap states density.This is consistent with the highest photovoltaic efficiency of 18.16%at 25%RH among the different relative humidities from 0%to 45%RH.展开更多
基金supported by NSF MRI (1428992)NASA EPSCoR (NNX15AM83A)+3 种基金U.S.–Egypt Science and Technology (S&T) Joint FundSDBoR R&D ProgramEDA University Center Program (ED18DEN3030025)supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC0206CH11357.
文摘Precise control over the charge carrier dynamics throughout the device can result in outstanding performance of perovskite solar cells(PSCs).Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is the most actively studied hole transport material in p-i-n structured PSCs.However,charge transport in the PEDOT:PSS is limited and inefficient because of its low conductivity with the presence of the weak ionic conductor PSS.In addition,morphology of the underlying PEDOT:PSS layer in PSCs plays a crucial role in determining the optoelectronic quality of the active perovskite absorber layer.This work is focused on realization of a non-wetting conductive surface of hole transport layer suitable for the growth of larger perovskite crystalline domains.This is accomplished by employing a facile solventengineered(ethylene glycol and methanol)approach resulting in removal of the predominant PSS in PEDOT:PSS.The consequence of acquiring larger perovskite crystalline domains was observed in the charge carrier dynamics studies,with the achievement of higher charge carrier lifetime,lower charge transport time and lower transfer impedance in the solvent-engineered PEDOT:PSS-based PSCs.Use of this solventengineered treatment for the fabrication of MAPbI3 PSCs greatly increased the device stability witnessing a power conversion efficiency of 18.18%,which corresponds to^37%improvement compared to the untreated PEDOT:PSS based devices.
基金supported by National Natural Science Foundation of China(Grant No.U1710256,U1810115 and 52072256)ShanXi Science and Technology Major Project(Grant No.20181102018,20181102019 and 20201101016)
文摘Transition-metal phosphides(TMPs)-based hybrid structure have received considerable attention for efficient sodium storage owing to their high capacity and decent reversibility.However,the volume expansion&the poor electronic conductivity of TMPs,the poor-rate capability,and fast capacity decay greatly hinder its practical application.To address these issues,a low-cost and facile strategy for the synthesis of Ni,N-codoped graphitized carbon(C)and cobalt phosphide(CoP)embedded in carbon fiber(Ni-CoP@CN⊂CF)as self-supporting anode material is demonstrated for the first time.The graphitized carbon and carbon fiber improve the electrical conductivity and inhibit the volume expansion issues.In addition to that,the microporous structure,and ultrasmall sized Ni-CoP offer a high surface area for electrolyte wettability,short Na-ion diffusion path and fast charge transport kinetics.As a result,outstanding electrochemical performance with an average capacity decay of 0.04%cycle^(−1)at 2000 mA g^(−1),an excellent rate capability of 270 mAh g^(−1)@2000 mA g^(−1)and a high energy density of~231.1 Wh kg^(−1)is achieved with binder-free self-supporting anode material.This work shows a potential for designing binder-free and high energy density sodium-ion batteries.
基金supported by the National Natural Science Foundation of China(Nos.52301282 and 52072256)Shanxi Province Science and Technology Program Unveiled Bidding Program(No.20201101016)+2 种基金Key Research and Development Program of Shanxi Province(Nos.202102030201006 and 202202070301016)Central Guidance for Local Science and Technology Development Funds Program(No.YDZJSX2021B005)Science and Technology Innovation Base Construction Program of Shanxi Province(No.YDZJSX2022B003).
文摘While neutral aqueous metal batteries,featuring cost-effectiveness and non-flammability,hold significant potential for large-scale energy storage,their practical application is hampered by the limited specific capacity of cathode materials(<500 mAh g^(-1)).Herein,capacity-oriented CoS2 and rate-optimized Co9S8 cathodes are developed based on the aqueous copper ion system.The charge-storage mechanism is sys-tematically investigated through a series of ex-situ tests and density functional theory calculations,fo-cusing on the reversible transitions of Co9S8→Cu7S4→Cu9S5/Cu1.8S and CoS2→Cu7S4→Cu2S,which are associated with the redox reactions of Cu^(2+)/Cu^(+)‖Co^(2+)/Co and Cu^(2+)/Cu^(+)‖S22-/S2-,respectively.The elec-trochemical results show that CoS2 can exhibit a superior capacity of 619 mAh g^(-1) at 1 A g^(-1) after 400 cycles,while Co9S8 maintains an outstanding rate performance of 497 mAh g^(-1) at 10 A g^(-1)(the retention rate is 95%compared to 521 mAh g1 at 1 A g^(-1)).As a proof of concept,an advanced CoS2//Zn hybrid aqueous battery demonstrates a working voltage of 1.20 V and a specific energy of 663 Wh kgcathode-1.This work provides an alternative direction for developing sulfide cathodes in energetic aqueous metal batteries.
基金This work has been supported in part by NSF MRI(1428992)NASA EPSCoR(NNX15AM83A)+3 种基金U.S.-Egypt Science and Technology(S&T)Joint Fund,SDBoR R&D Program,and EDA University Center Program(ED18DEN3030025)This work is derived from the Subject Data supported in whole or part by NAS and USAID,and any opinions,findings,conclusions,or recommendations expressed in the paper are those of the authors alone,and do not necessarily reflect the views of USAID or NAS.We would like to thank Dr Brian Moore for assisting us with high performance computing facility at South Dakota State University.W.Y.acknowledges the support from International Cooperation Project of Anhui Province(1503062018)Visiting Research Scholar Project for Young/Middle Excellent Talents of Anhui Province(gxfxZD2016110)Preeminent Youth Foundation of Anhui Polytechnic University(2016JQ002).
文摘In this work,grain boundary(GB)potential barrier(ΔφGB),dopant density(Pnet),and filled trap state density(PGB,trap)were manipulated at the nanoscale by exposing the fabricated perovskite films to various relative humidity(RH)environments.Spatial mapping of surface potential in the perovskite film revealed higher positive potential at GBs than inside the grains.The averageΔφGB,Pnet,and PGB,trap in the perovskite films decreased from 0%RH to 25%RH exposure,but increased when the RH increased to 35%RH and 45%RH.This clearly indicated that perovskite solar cells fabricated at 25%RH led to the lowest average GB potential,smallest dopant density,and least filled trap states density.This is consistent with the highest photovoltaic efficiency of 18.16%at 25%RH among the different relative humidities from 0%to 45%RH.
