There have been huge achievements of all-perovskite tandem solar cells,which recently realized the highest power conversion efficiency of 24.8%.However,the complex device structure and complicated manufacture processe...There have been huge achievements of all-perovskite tandem solar cells,which recently realized the highest power conversion efficiency of 24.8%.However,the complex device structure and complicated manufacture processes severely restrict the further development of all-perovskite tandem solar cells.In this work,we successfully fabricated high-efficiency hole transport material-free(HTM-free)Sn−Pb alloyed narrow bandgap perovskite solar cells(PSCs)by introducing guanidinium thiocyanate(GASCN)and hydroiodic acid(HI)into the perovskite precursor solution.GASCN and HI play a positive synergy effect during perovskite crystallization process resulting in larger grain size,fewer surface defects,and lower trap density to suppress the Sn^(2+)oxidation degradation.Furthermore,they could effectively adjust the energy level of perovskite materials,reduce the energy level difference between perovskite and ITO resulting in more efficiently transport of free hole charge carriers.As a result,with adding GASCN and HI,the achieved highest power conversion efficiency of HTM-free devices increased from 12.58%to 17.85%,which is one of the highest PCEs among all values reported to date for the HTM-free narrow-bandgap(1.2-1.4 eV)Sn−Pb binary PSCs.Moreover,the optimized device shows improved environmental stability.Our additive strategy manifests a remarkable step towards the facile,cost-efficient fabrication of HTM-free perovskite-based tandem solar cells with both high efficiency and simple fabrication process.展开更多
By employing the minimum energy theorem, the Potential energy controlling equation, which consists of surface energy and gravitational energy for molten meniscus, was investigated. The soder joint geometry of molten t...By employing the minimum energy theorem, the Potential energy controlling equation, which consists of surface energy and gravitational energy for molten meniscus, was investigated. The soder joint geometry of molten tin-lead soder alloy for chip component and thin quad flat package were simulated with finite element method. The simulation results 0f solder joint geometry are coincident well with the experimental results. The solder joint geometry was applied to study the solder joint reliability for chip component RC3216.The thermal cycling tests revealed that the solder joint geometry plays an important ro1e in solder joint reliability.展开更多
The temperature rise caused by plastic deformation during the quick upsetting of tin-lead alloy and mild steel was investigated via experiments and numerical simulations aiming at a better understanding of the heat ge...The temperature rise caused by plastic deformation during the quick upsetting of tin-lead alloy and mild steel was investigated via experiments and numerical simulations aiming at a better understanding of the heat generation mechanism in friction welding. The results show that the compression amount and deformation temperature influence significantly the temperature rise during the upsetting of tin-lead alloy. The temperature rise increases with increasing the compression but decreases with increasing the deformation temperature. The simulation results are in good agreement with the experimental inspection for Sn63A alloy. The simulation results of mild steel present a similar tendency with tin-lead alloy. Moreover, the temperature rise of mild steel at elevated temperatures is comparable to that of tin-lead alloy at low temperatures.展开更多
Sn60Pb40 al oy powders were fabricated using the planar flow casting （PFC） atomization process. By using OM, SEM and EPMA, the characteristics of the morphologies and microstructures of the powders have been investi...Sn60Pb40 al oy powders were fabricated using the planar flow casting （PFC） atomization process. By using OM, SEM and EPMA, the characteristics of the morphologies and microstructures of the powders have been investigated. It is observed that the environment of ambient gas in the atomization box has great effects on the morphology of the al oy powders. The microstructures of Sn60Pb40 al oy powders produced by the PFC atomization process are completely composed of eutectic, which is made up of both oversaturated αsolid solution and β solid solution. The microstructures of smal size powders are extraordinarily undeveloped dendritic eutectic, in which the large majority of the α phase appears nearly spherical, evidently since the cooling rate is higher and the under-cooling is larger. As for the large size powders, since the cooling rate and undercooling are relatively low, lamel ar α phase apparently increases in the eutectic microstructures of these powders, and there is even typical lamellar eutectic structure clearly observed in some micro-areas. After remelting tests by DTA, the microstructures of smal size powders are transformed, which become composed of large crumby α phase and eutectic （α＋β）, while those of large size powders change into classical tin-lead structures of primary α phase plus lamellar eutectic （α＋β）. By studying the microstructures of tin-lead alloy powders, a model has been proposed to predict the microstructure formation of Sn60Pb40 al oy powders.展开更多
The research on the influence of RE on the directional solidified microstructure of tin lead alloy reveals that the addition of RE can cause chopping and irregular lamellar and smaller lamellar spacing. When RE conte...The research on the influence of RE on the directional solidified microstructure of tin lead alloy reveals that the addition of RE can cause chopping and irregular lamellar and smaller lamellar spacing. When RE content increases, the microstructure changes to peritectic structure. Moreover, the eutectic point of Sn Pb alloy deviates because the affinity of RE for Sn, which results in the existence of primary Pb rich phases contained hypocutectic grown layers. Sn RE intermetallic compound has no effect on the solidification of Sn Pb alloy.展开更多
Mixed tin-lead iodide perovskites exhibit the characteristics of low toxicity and improved light harvesting ability up to nearinfrared(NIR) spectral region, making them as an attractive alternative for traditional lea...Mixed tin-lead iodide perovskites exhibit the characteristics of low toxicity and improved light harvesting ability up to nearinfrared(NIR) spectral region, making them as an attractive alternative for traditional lead based perovskites. However, the performance of lead-based perovskites solar cells is still far inferior to their lead analogues owing to the unavoidable oxidation of Sn^(2+)to Sn^(4+). Here we introduced two-dimensional(2D) perovskite on the top of three dimensional(3D) perovskite film as a capping layer to reduce the self-oxidation, and thus improved the device stability. 2D capping layer was then confirmed by X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) analysis. The existence of the 2D protecting thin layer significantly reduce the spontaneous Sn^(2+)oxidation, thus improve the device performance and reduce the hysteresis. The phenomena could be ascribed to the improved charge extraction efficiency causing by prohibited nonradiative recombination. On top of this, the photovoltaic devices based on conventional-structure configuration were fabricated. Taking advantage of the 2D capping layer, 2D/3D hybrid perovskite photovoltaic devices achieve a open-circuit voltage(Voc) of 0.77 V with short circuit current density(Jsc) of 26.60 mA cm^(-2), delivering the best-performing power conversion efficiency of 15.5%. Moreover, the 2D/3D perovskite devices maintained 60% its initial efficiency after 40 h exposed in air(humidity around 30%, temperature 22 °C),while 3D perovskite-based devices completely failed.展开更多
Perovskites are a category of materials with a unique crystal structure that allows them to absorb sunlight efficiently. This efficiency is particularly high in the case of CH<sub>3</sub>NH<sub>3<...Perovskites are a category of materials with a unique crystal structure that allows them to absorb sunlight efficiently. This efficiency is particularly high in the case of CH<sub>3</sub>NH<sub>3</sub>Pb<sub>1-x</sub>Sn<sub>x</sub>I<sub>3</sub> mixed perovskites. The combination of lead (Pb) and tin (Sn) in this matrix provides a broad spectrum of sunlight absorption, enabling the generation of a larger voltage and, subsequently, increased power. The primary objective in solar cell development is to maximize the conversion of sunlight into electricity. Mixed perovskites like CH<sub>3</sub>NH<sub>3</sub>Pb<sub>1-x</sub>Sn<sub>x</sub>I<sub>3</sub> have demonstrated significant potential in this regard. Their tunable bandgap, courtesy of varying the Pb: Sn ratio, allows for the optimization of sunlight absorption. The result is solar cells that surpass many conventional counterparts in terms of energy efficiency. Another significant advantage of these mixed perovskite solar cells is their cost-effectiveness. They can be manufactured using solution-based processes, which are less expensive than the high-vacuum methods required for traditional silicon solar cells. While the prospects for mixed perovskite solar cells are undeniably promising, there are concerns about the toxicity of lead, a key component of these cells. Lead is known to have harmful effects on the environment and health. The aim of our work is to reduce or eliminate lead toxicity in the perovskite cell while maintaining its efficiency. Thus, in a theoretical and experimental approach, we obtained following efficiencies of samples: CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> (22.49%) CH<sub>3</sub>NH<sub>3</sub>Pb<sub>0.75</sub>Sn<sub>0.25</sub>I<sub>3</sub> (22.72%), CH<sub>3</sub>NH<sub>3</sub>Pb<sub>0.5</sub>Sn<sub>0.5</sub>I<sub>3</sub> (23.00%) CH<sub>3</sub>NH<sub>3</sub>Pb<sub>0.25</sub>Sn<sub>0.75</sub>I<sub>3</sub> (22.61%), CH<sub>3</sub>NH<sub>3</sub>SnI<sub>3</sub> (22.38%). Doping with 50% tin gives the highest result (23.00%). By replacing a fraction of the lead with tin, the research aims to reduce the environmental footprint of the cells while maintaining their high performance. However, the challenge is to achieve a balance that does not compromise performance while reducing toxicity. .展开更多
基金financially supported by the Joint Funds Project funding from Guangdong Basic and Applied Basic Research Foundation(Grant No.2019B1515120083)the National Natural Science Foundation of China(Grant No.U19A2089)+4 种基金the Key Fundamental Research Project funding from the Shenzhen Science and Technology Innovation Committee(Grant No.JCYJ20200109141014474)the National Key Research and Development Project from the Ministry of Science and Technology of China(Grants Nos.2016YFA0202400 and 2016YFA0202404)the Peacock Team Project from Shenzhen Science and Technology Innovation Committee(Grant No.KQTD2015033110182370)Shenzhen Engineering R&D Center for Flexible Solar Cells project funding from Shenzhen Development and Reform Committee(Grant No.2019-126)the Guangdong-Hong Kong-Macao Joint Laboratory(Grant No.2019B121205001).
文摘There have been huge achievements of all-perovskite tandem solar cells,which recently realized the highest power conversion efficiency of 24.8%.However,the complex device structure and complicated manufacture processes severely restrict the further development of all-perovskite tandem solar cells.In this work,we successfully fabricated high-efficiency hole transport material-free(HTM-free)Sn−Pb alloyed narrow bandgap perovskite solar cells(PSCs)by introducing guanidinium thiocyanate(GASCN)and hydroiodic acid(HI)into the perovskite precursor solution.GASCN and HI play a positive synergy effect during perovskite crystallization process resulting in larger grain size,fewer surface defects,and lower trap density to suppress the Sn^(2+)oxidation degradation.Furthermore,they could effectively adjust the energy level of perovskite materials,reduce the energy level difference between perovskite and ITO resulting in more efficiently transport of free hole charge carriers.As a result,with adding GASCN and HI,the achieved highest power conversion efficiency of HTM-free devices increased from 12.58%to 17.85%,which is one of the highest PCEs among all values reported to date for the HTM-free narrow-bandgap(1.2-1.4 eV)Sn−Pb binary PSCs.Moreover,the optimized device shows improved environmental stability.Our additive strategy manifests a remarkable step towards the facile,cost-efficient fabrication of HTM-free perovskite-based tandem solar cells with both high efficiency and simple fabrication process.
文摘By employing the minimum energy theorem, the Potential energy controlling equation, which consists of surface energy and gravitational energy for molten meniscus, was investigated. The soder joint geometry of molten tin-lead soder alloy for chip component and thin quad flat package were simulated with finite element method. The simulation results 0f solder joint geometry are coincident well with the experimental results. The solder joint geometry was applied to study the solder joint reliability for chip component RC3216.The thermal cycling tests revealed that the solder joint geometry plays an important ro1e in solder joint reliability.
文摘The temperature rise caused by plastic deformation during the quick upsetting of tin-lead alloy and mild steel was investigated via experiments and numerical simulations aiming at a better understanding of the heat generation mechanism in friction welding. The results show that the compression amount and deformation temperature influence significantly the temperature rise during the upsetting of tin-lead alloy. The temperature rise increases with increasing the compression but decreases with increasing the deformation temperature. The simulation results are in good agreement with the experimental inspection for Sn63A alloy. The simulation results of mild steel present a similar tendency with tin-lead alloy. Moreover, the temperature rise of mild steel at elevated temperatures is comparable to that of tin-lead alloy at low temperatures.
基金supported by the Natural Science Foundation of Liaoning Province (No.20072043)
文摘Sn60Pb40 al oy powders were fabricated using the planar flow casting （PFC） atomization process. By using OM, SEM and EPMA, the characteristics of the morphologies and microstructures of the powders have been investigated. It is observed that the environment of ambient gas in the atomization box has great effects on the morphology of the al oy powders. The microstructures of Sn60Pb40 al oy powders produced by the PFC atomization process are completely composed of eutectic, which is made up of both oversaturated αsolid solution and β solid solution. The microstructures of smal size powders are extraordinarily undeveloped dendritic eutectic, in which the large majority of the α phase appears nearly spherical, evidently since the cooling rate is higher and the under-cooling is larger. As for the large size powders, since the cooling rate and undercooling are relatively low, lamel ar α phase apparently increases in the eutectic microstructures of these powders, and there is even typical lamellar eutectic structure clearly observed in some micro-areas. After remelting tests by DTA, the microstructures of smal size powders are transformed, which become composed of large crumby α phase and eutectic （α＋β）, while those of large size powders change into classical tin-lead structures of primary α phase plus lamellar eutectic （α＋β）. By studying the microstructures of tin-lead alloy powders, a model has been proposed to predict the microstructure formation of Sn60Pb40 al oy powders.
文摘The research on the influence of RE on the directional solidified microstructure of tin lead alloy reveals that the addition of RE can cause chopping and irregular lamellar and smaller lamellar spacing. When RE content increases, the microstructure changes to peritectic structure. Moreover, the eutectic point of Sn Pb alloy deviates because the affinity of RE for Sn, which results in the existence of primary Pb rich phases contained hypocutectic grown layers. Sn RE intermetallic compound has no effect on the solidification of Sn Pb alloy.
基金supported by the National Natural Science Foundation of China(21771114)MOE 111(B12015)+2 种基金the Natural Science Foundation of Tianjin(17JCYBJC40900,18YFZCGX00580)the Fundamental Research Funds for the Central Universitiesthe financial support from "Thousand Youth Talents Plan of China"
文摘Mixed tin-lead iodide perovskites exhibit the characteristics of low toxicity and improved light harvesting ability up to nearinfrared(NIR) spectral region, making them as an attractive alternative for traditional lead based perovskites. However, the performance of lead-based perovskites solar cells is still far inferior to their lead analogues owing to the unavoidable oxidation of Sn^(2+)to Sn^(4+). Here we introduced two-dimensional(2D) perovskite on the top of three dimensional(3D) perovskite film as a capping layer to reduce the self-oxidation, and thus improved the device stability. 2D capping layer was then confirmed by X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) analysis. The existence of the 2D protecting thin layer significantly reduce the spontaneous Sn^(2+)oxidation, thus improve the device performance and reduce the hysteresis. The phenomena could be ascribed to the improved charge extraction efficiency causing by prohibited nonradiative recombination. On top of this, the photovoltaic devices based on conventional-structure configuration were fabricated. Taking advantage of the 2D capping layer, 2D/3D hybrid perovskite photovoltaic devices achieve a open-circuit voltage(Voc) of 0.77 V with short circuit current density(Jsc) of 26.60 mA cm^(-2), delivering the best-performing power conversion efficiency of 15.5%. Moreover, the 2D/3D perovskite devices maintained 60% its initial efficiency after 40 h exposed in air(humidity around 30%, temperature 22 °C),while 3D perovskite-based devices completely failed.
文摘Perovskites are a category of materials with a unique crystal structure that allows them to absorb sunlight efficiently. This efficiency is particularly high in the case of CH<sub>3</sub>NH<sub>3</sub>Pb<sub>1-x</sub>Sn<sub>x</sub>I<sub>3</sub> mixed perovskites. The combination of lead (Pb) and tin (Sn) in this matrix provides a broad spectrum of sunlight absorption, enabling the generation of a larger voltage and, subsequently, increased power. The primary objective in solar cell development is to maximize the conversion of sunlight into electricity. Mixed perovskites like CH<sub>3</sub>NH<sub>3</sub>Pb<sub>1-x</sub>Sn<sub>x</sub>I<sub>3</sub> have demonstrated significant potential in this regard. Their tunable bandgap, courtesy of varying the Pb: Sn ratio, allows for the optimization of sunlight absorption. The result is solar cells that surpass many conventional counterparts in terms of energy efficiency. Another significant advantage of these mixed perovskite solar cells is their cost-effectiveness. They can be manufactured using solution-based processes, which are less expensive than the high-vacuum methods required for traditional silicon solar cells. While the prospects for mixed perovskite solar cells are undeniably promising, there are concerns about the toxicity of lead, a key component of these cells. Lead is known to have harmful effects on the environment and health. The aim of our work is to reduce or eliminate lead toxicity in the perovskite cell while maintaining its efficiency. Thus, in a theoretical and experimental approach, we obtained following efficiencies of samples: CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> (22.49%) CH<sub>3</sub>NH<sub>3</sub>Pb<sub>0.75</sub>Sn<sub>0.25</sub>I<sub>3</sub> (22.72%), CH<sub>3</sub>NH<sub>3</sub>Pb<sub>0.5</sub>Sn<sub>0.5</sub>I<sub>3</sub> (23.00%) CH<sub>3</sub>NH<sub>3</sub>Pb<sub>0.25</sub>Sn<sub>0.75</sub>I<sub>3</sub> (22.61%), CH<sub>3</sub>NH<sub>3</sub>SnI<sub>3</sub> (22.38%). Doping with 50% tin gives the highest result (23.00%). By replacing a fraction of the lead with tin, the research aims to reduce the environmental footprint of the cells while maintaining their high performance. However, the challenge is to achieve a balance that does not compromise performance while reducing toxicity. .
