Two-dimensional(2D)precursor molecules-based surface treatment on three-dimensional(3D)lead halide perovskite(PVSK)has achieved huge successes,the in-depth understanding of the modification mechanism remains an urgent...Two-dimensional(2D)precursor molecules-based surface treatment on three-dimensional(3D)lead halide perovskite(PVSK)has achieved huge successes,the in-depth understanding of the modification mechanism remains an urgent need.Here the effect of alkyl-chain length on the reaction dynamics between alkylammonium salts(XI)and 3D PVSK matrix is studied,through examination of surface morphological and crystallographic properties of the 3D PVSK matrix.It is observed that the average crystallite size of 3D PVSK increases as XI is either spin-coated on 3D PVSK or penetrated through carbon-electrode(during the“in-situ healing”process).Secondary growth is observed for 3D PVSK,which is related to ion-exchanging reactions.Prolonging alkyl-chain length favors the secondary growth.Besides,the formation dynamics of 2D PVSK are studied.Adding alkyl-chain length increases the yields.The observations are thoroughly discussed with respect to the steric-hindrance effect held by alky-chains of XI molecule.The improved crystallization of 3D PVSK and increased yields of 2D PVSK help accelerate charge extraction and reduce recombination across the interface between PVSK and carbon-electrode(CE).Tuning alkyl-chain length of XI molecules,and the mass ratio between XI molecules and carbon black could mitigate the“in-situ healing”effect.Power conversion efficiency(PCE)of the carbonelectrode-based hole-conductor-free planar perovskite solar cells has been upgraded from 14% to 17%,and further upgraded to 20.4% by utilizing relatively thick CEs.Thanks to the hydrophobicity of long alkyl-chains owned by XI molecules,prolonged stability has been achieved on unsealed devices at the high-moisture environment(RH≈85%),meanwhile,shelf-stability up to 6400 h has been achieved.This study deepens the understanding of the 2D precursor-basing modification strategies.展开更多
The service life and properties of Carbon fiber reinforced polycarbonate (CF/PC) composites are seriously affected by ultraviolet radiation from outdoor exposure during aging. In this work, the changes of structure an...The service life and properties of Carbon fiber reinforced polycarbonate (CF/PC) composites are seriously affected by ultraviolet radiation from outdoor exposure during aging. In this work, the changes of structure and solid particle erosion resistance for CF/PC composites after ultraviolet irradiation were studied. It was shown that ultraviolet irradiation causes photo-oxygen aging and photo-fries re-arrangement of the composite, and the result was confirmed by FTIR. We correlated the solid particle erosion resistance with aging time, and found that the solid particle erosion resistance of CF/PC composites greatly decreased by UVB irradiation during 15 hours. Furthermore, the eroded material surface was analyzed using scanning electron microscope (SEM). It suggests that ultraviolet aging leads to plasticization and degradation, resulting in reduction of erosion resistance of the composite.展开更多
基金financial support of the National Natural Science Foundation of China(NSFC,No.62374185)the Key Scientific Research Project of Education Department of Hunan Province(No.22A0005)the financial support from the Fundamental Research Funds for the Central South University(No.2024ZZTS0478)。
文摘Two-dimensional(2D)precursor molecules-based surface treatment on three-dimensional(3D)lead halide perovskite(PVSK)has achieved huge successes,the in-depth understanding of the modification mechanism remains an urgent need.Here the effect of alkyl-chain length on the reaction dynamics between alkylammonium salts(XI)and 3D PVSK matrix is studied,through examination of surface morphological and crystallographic properties of the 3D PVSK matrix.It is observed that the average crystallite size of 3D PVSK increases as XI is either spin-coated on 3D PVSK or penetrated through carbon-electrode(during the“in-situ healing”process).Secondary growth is observed for 3D PVSK,which is related to ion-exchanging reactions.Prolonging alkyl-chain length favors the secondary growth.Besides,the formation dynamics of 2D PVSK are studied.Adding alkyl-chain length increases the yields.The observations are thoroughly discussed with respect to the steric-hindrance effect held by alky-chains of XI molecule.The improved crystallization of 3D PVSK and increased yields of 2D PVSK help accelerate charge extraction and reduce recombination across the interface between PVSK and carbon-electrode(CE).Tuning alkyl-chain length of XI molecules,and the mass ratio between XI molecules and carbon black could mitigate the“in-situ healing”effect.Power conversion efficiency(PCE)of the carbonelectrode-based hole-conductor-free planar perovskite solar cells has been upgraded from 14% to 17%,and further upgraded to 20.4% by utilizing relatively thick CEs.Thanks to the hydrophobicity of long alkyl-chains owned by XI molecules,prolonged stability has been achieved on unsealed devices at the high-moisture environment(RH≈85%),meanwhile,shelf-stability up to 6400 h has been achieved.This study deepens the understanding of the 2D precursor-basing modification strategies.
文摘The service life and properties of Carbon fiber reinforced polycarbonate (CF/PC) composites are seriously affected by ultraviolet radiation from outdoor exposure during aging. In this work, the changes of structure and solid particle erosion resistance for CF/PC composites after ultraviolet irradiation were studied. It was shown that ultraviolet irradiation causes photo-oxygen aging and photo-fries re-arrangement of the composite, and the result was confirmed by FTIR. We correlated the solid particle erosion resistance with aging time, and found that the solid particle erosion resistance of CF/PC composites greatly decreased by UVB irradiation during 15 hours. Furthermore, the eroded material surface was analyzed using scanning electron microscope (SEM). It suggests that ultraviolet aging leads to plasticization and degradation, resulting in reduction of erosion resistance of the composite.
