In this article, the vanadium pentoxide sols are synthesized by two different routes (melted and quenched in oxygen atmosphere or in air). The structure and properties of the vanadium pentoxide xerogel films are chara...In this article, the vanadium pentoxide sols are synthesized by two different routes (melted and quenched in oxygen atmosphere or in air). The structure and properties of the vanadium pentoxide xerogel films are characterized by XRD, ESR, cyclic voltammograms curves and UV-visible transmittance analysis. The results show that the sample prepared in oxygen has poorer crystallization, lower content of V4+ ions and higher Li+ insertion capacity compared with that prepared in air.展开更多
Ionic liquids(ILs)have been widely applied in the one-step fabrication of perovskite with noticeable enhancement in the device performance.However,in-depth mechanism of ionic-liquid-assisted perovskite film formation ...Ionic liquids(ILs)have been widely applied in the one-step fabrication of perovskite with noticeable enhancement in the device performance.However,in-depth mechanism of ionic-liquid-assisted perovskite film formation is not well understood for also important two-step perovskite fabrication method,with better control of crystallization behavior.In this work,we introduced ionic liquid methylammonium formate(MAFa)into organic salt to produce perovskite film via a two-step method.Systematic investigations on the influence of MAFa on the perovskite thin film formation mechanism were performed.Ionic liquid is shown to assist lowering the perovskite formation enthalpy upon the density functional theory(DFT)calculation,leading to an accelerated crystallization process evidenced by in-situ UV-Vis absorption measurement.A gradient up-down distribution of ionic liquid has been confirmed by timeof-flight SIMS.Importantly,besides the surface passivation,we found the HCOO-can diffuse into the perovskite crystals to fill up the halide vacancies,resulting in significant reduction of trap states.Uniform perovskite films with significantly larger grains and less defect density were prepared with the help of MAFa IL,and the corresponding device efficiency over 23%was obtained by two-step process with remarkably improved stability.This research work provides an efficient strategy to tune the morphology and opto-electronic properties of perovskite materials via ionic-liquid-assisted two-step fabrication method,which is beneficial for upscaling and application of perovskite photovoltaics.展开更多
Mixed-dimensional engineering of perovskite material has been demonstrated as a facile and promising strategy to improve both photovoltaic performance and long-term stability of perovskite solar cells(PSCs).In this st...Mixed-dimensional engineering of perovskite material has been demonstrated as a facile and promising strategy to improve both photovoltaic performance and long-term stability of perovskite solar cells(PSCs).In this study,we report an in-plane preferred orientation of 1D perovskite induced by an ionic liquid(IL)of 1-(3-cyanopropyl)-3-methylimidazolium chloride(CPMIMCl)for the first time via sequential deposition approach,leading to a mixed dimensional perovskite thin films.The generated one-dimensional(1D)CPMIMPbI3 with in-plane orientation resides at the grain boundaries of three-dimensional(3D)perovskite can be appreciably observed from the morphology level,leading to creation of high-quality films with large grain size with more efficient defect passivation.Moreover,the dispersion of IL in the bulk phase of perovskite material allows for the formation of 1D perovskite for multiple level passivation to inhibit non-radiative recombination and optimize carrier transport.This IL engineering strategy not only yields a mixed-dimensional perovskite heterostructure with in-plane orientation 1D perovskite nano-rods but also significantly improves the opto-electronic property with suppressed trap states.As a result,the CPMIMCl-treated PSCs show an enhanced photovoltaic performance with a champion power conversion efficiency(PCE)up to 24.13%.More importantly,benefiting from the hydrophobicity of formed 1D perovskite and defects suppression,the corresponding PSC demonstrates an excellent longterm stability and maintain 97.1%of its pristine PCE at 25C under 50%RH condition over 1000 h.This research provides an innovative perspective for employing the low dimensional engineering to optimize the performance and stability of photovoltaic devices.展开更多
基金This work was supported by the National Natural Science Foundation of China(grant No.50172036)the Teaching and Research Award Prograrn for Outstanding Young Professors in Higher Education Institute,MOE,P.R.China.
文摘In this article, the vanadium pentoxide sols are synthesized by two different routes (melted and quenched in oxygen atmosphere or in air). The structure and properties of the vanadium pentoxide xerogel films are characterized by XRD, ESR, cyclic voltammograms curves and UV-visible transmittance analysis. The results show that the sample prepared in oxygen has poorer crystallization, lower content of V4+ ions and higher Li+ insertion capacity compared with that prepared in air.
基金supported by the National Natural Science Foundation of China(Grant Nos.62004129,51472189,22005202)the Shenzhen Science and Technology Innovation Commission(JCYJ20200109105003940)+2 种基金the Research Grants Council of Hong Kong(GRF grant 15221320,CRF C5037-18G,C7018-20G)the Hong Kong Polytechnic University Funds(Sir Sze-yuen Chung Endowed Professorship Fund(8-8480)RISE(Q-CDA5)。
文摘Ionic liquids(ILs)have been widely applied in the one-step fabrication of perovskite with noticeable enhancement in the device performance.However,in-depth mechanism of ionic-liquid-assisted perovskite film formation is not well understood for also important two-step perovskite fabrication method,with better control of crystallization behavior.In this work,we introduced ionic liquid methylammonium formate(MAFa)into organic salt to produce perovskite film via a two-step method.Systematic investigations on the influence of MAFa on the perovskite thin film formation mechanism were performed.Ionic liquid is shown to assist lowering the perovskite formation enthalpy upon the density functional theory(DFT)calculation,leading to an accelerated crystallization process evidenced by in-situ UV-Vis absorption measurement.A gradient up-down distribution of ionic liquid has been confirmed by timeof-flight SIMS.Importantly,besides the surface passivation,we found the HCOO-can diffuse into the perovskite crystals to fill up the halide vacancies,resulting in significant reduction of trap states.Uniform perovskite films with significantly larger grains and less defect density were prepared with the help of MAFa IL,and the corresponding device efficiency over 23%was obtained by two-step process with remarkably improved stability.This research work provides an efficient strategy to tune the morphology and opto-electronic properties of perovskite materials via ionic-liquid-assisted two-step fabrication method,which is beneficial for upscaling and application of perovskite photovoltaics.
基金supported by the Scientific Research Startup Fund for Shenzhen High-Caliber Personnel of Shenzhen Polytechnic,No.6022310038k and 6022310049kThe financial support from the National Natural Science Foundation of China(No.62004129)+4 种基金Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011677)Shenzhen Science and Technology Innovation Commission(Project No.JCYJ20200109105003940,Project No.20220811205532001,Project NO.20220813171052002)Research Grants Council of Hong Kong(GRF grant 15221320,CRF C5037-18G,C7018-20G)the Hong Kong Polytechnic University funds(Sir Sze-yuen Chung Endowed Professorship Fund(8-8480)RISE(Q-CDA5))is gratefully acknowledged.The authors thank the AFM technical support from Oxford Instrument.
文摘Mixed-dimensional engineering of perovskite material has been demonstrated as a facile and promising strategy to improve both photovoltaic performance and long-term stability of perovskite solar cells(PSCs).In this study,we report an in-plane preferred orientation of 1D perovskite induced by an ionic liquid(IL)of 1-(3-cyanopropyl)-3-methylimidazolium chloride(CPMIMCl)for the first time via sequential deposition approach,leading to a mixed dimensional perovskite thin films.The generated one-dimensional(1D)CPMIMPbI3 with in-plane orientation resides at the grain boundaries of three-dimensional(3D)perovskite can be appreciably observed from the morphology level,leading to creation of high-quality films with large grain size with more efficient defect passivation.Moreover,the dispersion of IL in the bulk phase of perovskite material allows for the formation of 1D perovskite for multiple level passivation to inhibit non-radiative recombination and optimize carrier transport.This IL engineering strategy not only yields a mixed-dimensional perovskite heterostructure with in-plane orientation 1D perovskite nano-rods but also significantly improves the opto-electronic property with suppressed trap states.As a result,the CPMIMCl-treated PSCs show an enhanced photovoltaic performance with a champion power conversion efficiency(PCE)up to 24.13%.More importantly,benefiting from the hydrophobicity of formed 1D perovskite and defects suppression,the corresponding PSC demonstrates an excellent longterm stability and maintain 97.1%of its pristine PCE at 25C under 50%RH condition over 1000 h.This research provides an innovative perspective for employing the low dimensional engineering to optimize the performance and stability of photovoltaic devices.