Low-temperature,ambient processing of high-quality CsPbBr_(3)films is demanded for scalable production of efficient,low-cost carbon-electrode perovskite solar cells(PSCs).Herein,we demonstrate a crystal orientation en...Low-temperature,ambient processing of high-quality CsPbBr_(3)films is demanded for scalable production of efficient,low-cost carbon-electrode perovskite solar cells(PSCs).Herein,we demonstrate a crystal orientation engineering strategy of PbBr_(2)precursor film to accelerate its reaction with CsBr precursor during two-step sequential deposition of CsPbBr_(3)films.Such a novel strategy is proceeded by adding CsBr species into PbBr_(2)precursor,which can tailor the preferred crystal orientation of PbBr_(2)film from[020]into[031],with CsBr additive staying in the film as CsPb_(2)Br_(5)phase.Theoretical calculations show that the reaction energy barrier of(031)planes of PbBr_(2)with CsBr is lower about 2.28 eV than that of(O2O)planes.Therefore,CsPbBr_(3)films with full coverage,high purity,high crystallinity,micro-sized grains can be obtained at a low temperature of 150℃.Carbon-electrode PSCs with these desired CsPbBr_(3)films yield the record-high efficiency of 10.27%coupled with excellent operation stability.Meanwhile,the 1 cm^(2)area one with the superior efficiency of 8.00%as well as the flexible one with the champion efficiency of 8.27%and excellent mechanical bending characteristics are also achieved.展开更多
This article presents a three-dimensional analysis of the impact of the angle of incidence of the magnetic field intensity on the electrical performance (series resistance, shunt resistance) of a bifacial polycrystall...This article presents a three-dimensional analysis of the impact of the angle of incidence of the magnetic field intensity on the electrical performance (series resistance, shunt resistance) of a bifacial polycrystalline silicon solar cell. The cell is illuminated simultaneously from both sides. The continuity equation for the excess minority carriers is solved at the emitter and at the depth of the base respectively. The analytical expressions for photocurrent density, photovoltage, series resistance and shunt resistance were deduced. Using these expressions, the values of the series and shunt resistances were extracted for different values of the angle of incidence of the magnetic field intensity. The study shows that as the angle of incidence increases, the slopes of the minority carrier density for the two modes of operation of the solar cell decrease. This is explained by a drop in the accumulation of carriers in the area close to the junction due to the fact that the Lorentz force is unable to drive the carriers towards the lateral surfaces due to the weak action of the magnetic field, which tends to cancel out as the incidence angle increases, and consequently a drop in the open circuit photovoltage. This, in turn, reduces the Lorentz force. These results predict that the p-n junction of the solar cell will not heat up. The study also showed a decrease in series resistance as the incidence angle of the magnetic field intensity increased from 0 rad to π/2 rad and an increase in shunt resistance as the incidence angle increased. His behaviour of the electrical parameters when the angle of incidence of the field from 0 rad to π/2 rad shows that the decreasing magnetic field vector tends to be collinear with the electron trajectory. This allows them to cross the junction and participate in the external current. The best orientation for the Lorentz force is zero, in which case the carriers can move easily towards the junction.展开更多
In this study, the effects of temperature and frequency on minority carrier diffusion coefficient in silicon solar cell under a magnetic field are presented. Using two methods (analytic and graphical), the optimum tem...In this study, the effects of temperature and frequency on minority carrier diffusion coefficient in silicon solar cell under a magnetic field are presented. Using two methods (analytic and graphical), the optimum temperature corresponding to maximum diffusion coefficient is determined versus cyclotronic frequency and magnetic field.展开更多
This work deals with minority carrier diffusion coefficient study in silicon solar cell, under both temperature and applied magnetic field. New expressions of diffusion coefficient are pointed out, which gives attenti...This work deals with minority carrier diffusion coefficient study in silicon solar cell, under both temperature and applied magnetic field. New expressions of diffusion coefficient are pointed out, which gives attention to thermal behavior of minority carrier that is better understood with Umklapp process. This study allowed to determine an optimum temperature which led to maximum diffusion coefficient value while magnetic field remained constant.展开更多
The solar temperature field of a large three-span continuous bridge with steel-concrete composite box girder and variable cross-section is measured to verify a calculation method for the temperature field of steel-con...The solar temperature field of a large three-span continuous bridge with steel-concrete composite box girder and variable cross-section is measured to verify a calculation method for the temperature field of steel-concrete composite beams. The test results show that the temperature of an external steel web- plate is higher than that of an internal web-plate due to the difference in solar radiation. Air temperature inside the box matches the average temperature of the whole steel box. Based on actual measurements, a transient thermal analysis with multiple boundary conditions is also carried out by a software program ANSYS. Convective boundary situation and states of solar radiation on steel web plates in different situations are determined in the analysis. The feature of the temperature field is preliminarily achieved through a comparative study between the actual measurement and the finite element analysis. The computed results are in good consistence with the actual measurement results, with the maximum difference within 2 ℃. This indicates that the theoretical calculation method is reliable and it provides a foundation for further research on temperature field distribution in the steel-concrete composite box girder.展开更多
Enhancing the lifetime of perovskite solar cells(PSCs)is one of the essential challenges for their industrialization.Although the external encapsulation protects the perovskite device from the erosion of moisture and ...Enhancing the lifetime of perovskite solar cells(PSCs)is one of the essential challenges for their industrialization.Although the external encapsulation protects the perovskite device from the erosion of moisture and oxygen under various harsh conditions.However,the perovskite devices still undergo static and dynamic thermal stress during thermal and thermal cycling aging,respectively,resulting in irreversible damage to the morphology,component,and phase of stacked materials.Herein,the viscoelastic polymer polyvinyl butyral(PVB)material is designed onto the surface of perovskite films to form flexible interface encapsulation.After PVB interface encapsulation,the surface modulus of perovskite films decreases by nearly 50%,and the interface stress range under the dynamic temperature field(−40 to 85°C)drops from−42.5 to 64.8 MPa to−14.8 to 5.0 MPa.Besides,PVB forms chemical interactions with FA+cations and Pb^(2+),and the macroscopic residual stress is regulated and defects are reduced of the PVB encapsulated perovskite film.As a result,the optimized device's efficiency increases from 22.21%to 23.11%.Additionally,after 1500 h of thermal treatment(85°C),1000 h of damp heat test(85°C&85%RH),and 250 cycles of thermal cycling test(−40 to 85°C),the devices maintain 92.6%,85.8%,and 96.1%of their initial efficiencies,respectively.展开更多
Solar cells and other renewable energy sources are crucial in today's world where sustainability and environmental consciousness is at peak.Because of this,creating the optimal capacity is a fair aim for the opera...Solar cells and other renewable energy sources are crucial in today's world where sustainability and environmental consciousness is at peak.Because of this,creating the optimal capacity is a fair aim for the operators of such technologies.The transformation of solar energy into either electricity by means of photovoltaics or into useable fuel by means of photo electrochemical cells remained a primary objective for research organizations and development sectors.In this piece,we will take a look back at the history of solar cells and examine their progression through the generations.The significant aspects which have an impact on the solar cells' performance are also discussed.This article provides a comprehensive and in-depth overview of the important aspects that affect the solar cells' performance,as well as a discussion of the application of bio-inspired optimization algorithms to improve the parameters of solar cells.Reviewing critical factors and their optimization for solar cell performance enhancement is crucial.It helps identify key performance factors,understand limitations,and challenges,and identify effective optimization strategies.By evaluating trade-offs and synergies,it guides future research and informs industrial applications,leading to more efficient and sustainable solar cell technologies.展开更多
Based on transient temperature field theory of heat conduction, the solar temperature field calculation model of U-shape sectioned high-speed railway cable-stayed bridge under actions of concrete beams and ballast was...Based on transient temperature field theory of heat conduction, the solar temperature field calculation model of U-shape sectioned high-speed railway cable-stayed bridge under actions of concrete beams and ballast was established. Using parametric programming language, finite element calculation modules considering climate conditions, bridge site, structure dimension and material thermophysical properties were compiled. Six standard day cycles with the strongest yearly radiation among the bridge sites were selected for sectional solar temperature field calculation and temperature distributions under different temperature-sensitive parameters were compared. The results show that under the influence of sunshine, U-shape section of the beam shows obvious nonlinear distribution characteristics and the maximum cross-section temperature difference is more than 21℃; the ballast significantly reduces sunshine temperature difference of the beam and temperature peak of the bottom margin lags with the increase of ballast thickness; the maximum cross-section vertical temperature gradient appears in summer while large transverse temperature difference appears in winter.展开更多
The paper reported a theoretical study on the photoconductivity of a bifacial silicon solar cell under polychromatic illumination and a constant magnetic field effect. By use of the continuity equation in the base of ...The paper reported a theoretical study on the photoconductivity of a bifacial silicon solar cell under polychromatic illumination and a constant magnetic field effect. By use of the continuity equation in the base of the solar cell maintained in a constant temperature at 300 K, an expression of the excess minority carriers’ density was determined according to the applied magnetic field, the base depth and the junction recombination velocity. From the expression of the minority carriers’ density, the photoconductivity of the solar cell was deduced and which allowed us to predict some recombination phenomena, the use of such solar cell in optoelectronics. The profile of the photoconductivity also permitted us to utilize a linear model in order to determine an electrical capacitance that varied with magnetic field.展开更多
Here we demonstrate a room-temperature drop-coating method for MAPbI_(3) films.By using low-boiling-point solvent,high-quality MAPbI_(3) films were made by simply casting a drop of solution onto the substrate at room ...Here we demonstrate a room-temperature drop-coating method for MAPbI_(3) films.By using low-boiling-point solvent,high-quality MAPbI_(3) films were made by simply casting a drop of solution onto the substrate at room temperature.This approach took advantage of the synergistic effect of good wettability and volatility of the solvent,enabling high nuclei density and compact film at room temperature.The crystal growth in different solvents was in-situ observed by using optical microscope,which helped us to understand the mechanism for the formation of different film morphology.Perovskite solar cells gave a PCE of 18.21%.展开更多
This paper identifies the contributions of p-a-SiC:H layers and i-a-Si:H layers to the open circuit voltage of p-i-n type a-Si:H solar cells deposited at a low temperature of 125℃. We find that poor quality p-a-Si...This paper identifies the contributions of p-a-SiC:H layers and i-a-Si:H layers to the open circuit voltage of p-i-n type a-Si:H solar cells deposited at a low temperature of 125℃. We find that poor quality p-a-SiC:H films under regular conditions lead to a restriction of open circuit voltage although the band gap of the i-layer varies widely. A significant improvement in open circuit voltage has been obtained by using high quality p-~SiC:H films optimized at the "low-power regime" under low silane flow rates and high hydrogen dilution conditions.展开更多
In static regime with polychromatic illumination, using the expression of the solar cell capacitance to determine the silicon solar cell capacitance C<sub>0</sub>(T) in short-circuit, is the purpose of thi...In static regime with polychromatic illumination, using the expression of the solar cell capacitance to determine the silicon solar cell capacitance C<sub>0</sub>(T) in short-circuit, is the purpose of this article. The expression of the excess minority carries density δ(x) from the continuity equation. The expression of δ(x) is used to determine the photovoltage expression. The capacitance efficiency dependence on X<sub>cc</sub>(T) is studied. X<sub>cc</sub>(T) is the abscissa of the maximum of δ(x).展开更多
The effect of the deposition temperature of the buffer layer In_2S_3 on the band alignment of CZTS/In_2S_3 heterostructures and the solar cell performance have been investigated.The In_2S_3 films are prepared by therm...The effect of the deposition temperature of the buffer layer In_2S_3 on the band alignment of CZTS/In_2S_3 heterostructures and the solar cell performance have been investigated.The In_2S_3 films are prepared by thermal evaporation method at temperatures of 30,100,150,and 200 ℃,respectively.By using x-ray photoelectron spectroscopy(XPS),the valence band offsets(VBO) are determined to be-0.28 ±0.1,-0.28 ±0.1,-0.34 ±0.1,and-0.42 ±0.1 eV for the CZTS/In_2S_3heterostructures deposited at 30,100,150,and 200 ℃,respectively,and the corresponding conduction band offsets(CBO)are found to be 0.3 ±0.1,0.41 ±0.1,0.22±0.1,and 0.01 ±0.1 eV,respectively.The XPS study also reveals that interdiffusion of In and Cu occurs at the interface of the heterostructures,which is especially serious at 200 ℃ leading to large amount of interface defects or the formation of CuInS_2 phase at the interface.The CZTS solar cell with the buffer layer In_2S_3 deposited at 150 ℃ shows the best performance due to the proper CBO value at the heterostructure interface and the improved crystal quality of In_2S_3 film induced by the appropriate deposition temperature.The device prepared at 100 ℃presents the poorest performance owing to too high a value of CBO.It is demonstrated that the deposition temperature is a crucial parameter to control the quality of the solar cells.展开更多
In order to enhance the p-type doping concentration in the LBSF, boron was added into the aluminum paste and boron doped local back surface field(B-LBSF) was successfully fabricated in this work. Through boron dopin...In order to enhance the p-type doping concentration in the LBSF, boron was added into the aluminum paste and boron doped local back surface field(B-LBSF) was successfully fabricated in this work. Through boron doping in the LBSF, much higher doping concentration was observed for the B-LBSF over the Al-LBSF. Higher doping concentration in the LBSF is expected to lead to better rear passivation and lower rear contact resistance. Based on one thousand pieces of solar cells for each type, it was found that the rear passivated crystalline silicon solar cells with B-LBSF showed statistical improvement in their photovoltaic properties over those with Al-LBSF.展开更多
In this paper, a theory on the determination of the diffusion coefficient of excess minority carriers in the base of a silicon solar cell is presented. The diffusion coefficient expression has been established and is ...In this paper, a theory on the determination of the diffusion coefficient of excess minority carriers in the base of a silicon solar cell is presented. The diffusion coefficient expression has been established and is related to both frequency modulation and applied magnetic field;the study is then carried out using the impedance spectroscopy method and Bode diagrams. From the diffusion coefficient, we deduced the diffusion length and the minority carriers’ mobility. Electric parameters were derived from the diffusion coefficient equivalent circuits.展开更多
The ac recombination velocity of the excess minority carriers, in the back surface of a silicon solar cell with a vertical junction connected in series, is developed through Einstein’s law giving the diffusion coeffi...The ac recombination velocity of the excess minority carriers, in the back surface of a silicon solar cell with a vertical junction connected in series, is developed through Einstein’s law giving the diffusion coefficient of minority carriers according to temperature, through mobility. The frequency spectrum of both, amplitude and phase, are produced for the diffusion coefficient and the recombination velocity in the rear face, in order to identify the parameters of equivalent electric models.展开更多
The aim of this work is to present a theoretical study of external magnetic field effect on a bifacial silicon solar cell’s electrical parameters (peak power, fill factor and load resistance) using the J-V and P-V ch...The aim of this work is to present a theoretical study of external magnetic field effect on a bifacial silicon solar cell’s electrical parameters (peak power, fill factor and load resistance) using the J-V and P-V characteristics. After the resolution of the magneto transport equation and continuity equation of excess minority carriers in the base of the bifacial silicon solar cell under multispectral illumination, the photo-current density and the photovoltage are determined and the J-V and P-V curves are plotted. Using simultaneously the J-V and P-V curves, we determine, according to magnetic field intensity, the peak photocurrent density, the peak photovoltage, the peak electric power, the fill factor and the load resistance at the peak power point. The numerical data show that the solar cell’s peak power decreases with magnetic field intensity while the fill factor and the load resistance increase.展开更多
The aim of this work is to investigate, with a three-dimensional steady-state approach, the effect of the incidence angle of a magnetic field on the performance of a polycrystalline silicon solar cell under multispect...The aim of this work is to investigate, with a three-dimensional steady-state approach, the effect of the incidence angle of a magnetic field on the performance of a polycrystalline silicon solar cell under multispectral illumination. The magneto-transport and continuity equations of excess minority carriers are solved to find the expression of the density of excess minority carriers and the related electrical parameters, such as the photocurrent density, the photovoltage and the electric power, of a grain of the polycrystalline silicon solar cell. The influence of the incidence angle of the magnetic field on the diffusion coefficient, the short-circuit photocurrent density, the open-circuit photovoltage and the electric power-photovoltage is studied. Then, the curves of the electric power-photovoltage is used to find the maximum electric power allowing to calculate, according to the incidence angle of the magnetic field, the fill factor and the conversion efficiency. The study has shown that the increase of the incidence angle of the magnetic field from 0 rad to π/2 rad, can reduce the degradation of the performance of solar cells.展开更多
The temperature of a solar cell subjected to the incident global solar radiation as a function of the local day time is determined. A heat balance equation is solved considering the heat losses due to convection and t...The temperature of a solar cell subjected to the incident global solar radiation as a function of the local day time is determined. A heat balance equation is solved considering the heat losses due to convection and thermal radiation. The cell efficiency is estimated as a measure of its performance. The results reveal that the temperature within the cell attains significant values. Nevertheless, the temperature dependence of its efficiency along the day time is not pronouncing. It slightly decreases with temperature.展开更多
In recent years perovskite solar cells have attracted an increasing scientific and technological interest in the scientific community. It is important to know that the temperature is one of the factors which have a st...In recent years perovskite solar cells have attracted an increasing scientific and technological interest in the scientific community. It is important to know that the temperature is one of the factors which have a strong effect on the efficiency of perovskite solar cell. This study communicates a temperature analysis on the pho- tovoltaic parameters of CH3NH3Pbl3-based perovskite solar cell in a broad interval from 80 to 360 K. Strong temperature-dependent photovoltaic effects have been observed in the type of solar cell, which could be mainly attributed to CH3NH3PbI3, showing a ferroelectric-paraelectric phase transition at low temperature (T 〈 160 K). An increase in temperature over the room temperature decreased the perovskite solar cell performance and reduced its efficiency from 16Z to 9%. The investigation with electronic impedance spectroscopy reveals that at low temperature (T 〈 120 K) the charge transport layer limits the device performance, while at high temperature (T 〉 200 K), the interfacial charge recombination becomes the dominant factor.展开更多
基金the financial support from the National Key R&D program of China(2021YFF0500501 and 2021YFF0500504)the Fundamental Research Funds for the Central Universities(YJS2213 and JB211408)+1 种基金the National Natural Science Foundation of China(61874083)the Joint Research Funds of Department of Science&Technology of Shaanxi Province and Northwestern Polytechnical University(No.2020GXLH-Z-014)
文摘Low-temperature,ambient processing of high-quality CsPbBr_(3)films is demanded for scalable production of efficient,low-cost carbon-electrode perovskite solar cells(PSCs).Herein,we demonstrate a crystal orientation engineering strategy of PbBr_(2)precursor film to accelerate its reaction with CsBr precursor during two-step sequential deposition of CsPbBr_(3)films.Such a novel strategy is proceeded by adding CsBr species into PbBr_(2)precursor,which can tailor the preferred crystal orientation of PbBr_(2)film from[020]into[031],with CsBr additive staying in the film as CsPb_(2)Br_(5)phase.Theoretical calculations show that the reaction energy barrier of(031)planes of PbBr_(2)with CsBr is lower about 2.28 eV than that of(O2O)planes.Therefore,CsPbBr_(3)films with full coverage,high purity,high crystallinity,micro-sized grains can be obtained at a low temperature of 150℃.Carbon-electrode PSCs with these desired CsPbBr_(3)films yield the record-high efficiency of 10.27%coupled with excellent operation stability.Meanwhile,the 1 cm^(2)area one with the superior efficiency of 8.00%as well as the flexible one with the champion efficiency of 8.27%and excellent mechanical bending characteristics are also achieved.
文摘This article presents a three-dimensional analysis of the impact of the angle of incidence of the magnetic field intensity on the electrical performance (series resistance, shunt resistance) of a bifacial polycrystalline silicon solar cell. The cell is illuminated simultaneously from both sides. The continuity equation for the excess minority carriers is solved at the emitter and at the depth of the base respectively. The analytical expressions for photocurrent density, photovoltage, series resistance and shunt resistance were deduced. Using these expressions, the values of the series and shunt resistances were extracted for different values of the angle of incidence of the magnetic field intensity. The study shows that as the angle of incidence increases, the slopes of the minority carrier density for the two modes of operation of the solar cell decrease. This is explained by a drop in the accumulation of carriers in the area close to the junction due to the fact that the Lorentz force is unable to drive the carriers towards the lateral surfaces due to the weak action of the magnetic field, which tends to cancel out as the incidence angle increases, and consequently a drop in the open circuit photovoltage. This, in turn, reduces the Lorentz force. These results predict that the p-n junction of the solar cell will not heat up. The study also showed a decrease in series resistance as the incidence angle of the magnetic field intensity increased from 0 rad to π/2 rad and an increase in shunt resistance as the incidence angle increased. His behaviour of the electrical parameters when the angle of incidence of the field from 0 rad to π/2 rad shows that the decreasing magnetic field vector tends to be collinear with the electron trajectory. This allows them to cross the junction and participate in the external current. The best orientation for the Lorentz force is zero, in which case the carriers can move easily towards the junction.
文摘In this study, the effects of temperature and frequency on minority carrier diffusion coefficient in silicon solar cell under a magnetic field are presented. Using two methods (analytic and graphical), the optimum temperature corresponding to maximum diffusion coefficient is determined versus cyclotronic frequency and magnetic field.
文摘This work deals with minority carrier diffusion coefficient study in silicon solar cell, under both temperature and applied magnetic field. New expressions of diffusion coefficient are pointed out, which gives attention to thermal behavior of minority carrier that is better understood with Umklapp process. This study allowed to determine an optimum temperature which led to maximum diffusion coefficient value while magnetic field remained constant.
文摘The solar temperature field of a large three-span continuous bridge with steel-concrete composite box girder and variable cross-section is measured to verify a calculation method for the temperature field of steel-concrete composite beams. The test results show that the temperature of an external steel web- plate is higher than that of an internal web-plate due to the difference in solar radiation. Air temperature inside the box matches the average temperature of the whole steel box. Based on actual measurements, a transient thermal analysis with multiple boundary conditions is also carried out by a software program ANSYS. Convective boundary situation and states of solar radiation on steel web plates in different situations are determined in the analysis. The feature of the temperature field is preliminarily achieved through a comparative study between the actual measurement and the finite element analysis. The computed results are in good consistence with the actual measurement results, with the maximum difference within 2 ℃. This indicates that the theoretical calculation method is reliable and it provides a foundation for further research on temperature field distribution in the steel-concrete composite box girder.
基金the National Natural Science Foundation of China(U21A20172,21975028)the China Postdoctoral Science Foundation under Grant Number 2023 M740167.
文摘Enhancing the lifetime of perovskite solar cells(PSCs)is one of the essential challenges for their industrialization.Although the external encapsulation protects the perovskite device from the erosion of moisture and oxygen under various harsh conditions.However,the perovskite devices still undergo static and dynamic thermal stress during thermal and thermal cycling aging,respectively,resulting in irreversible damage to the morphology,component,and phase of stacked materials.Herein,the viscoelastic polymer polyvinyl butyral(PVB)material is designed onto the surface of perovskite films to form flexible interface encapsulation.After PVB interface encapsulation,the surface modulus of perovskite films decreases by nearly 50%,and the interface stress range under the dynamic temperature field(−40 to 85°C)drops from−42.5 to 64.8 MPa to−14.8 to 5.0 MPa.Besides,PVB forms chemical interactions with FA+cations and Pb^(2+),and the macroscopic residual stress is regulated and defects are reduced of the PVB encapsulated perovskite film.As a result,the optimized device's efficiency increases from 22.21%to 23.11%.Additionally,after 1500 h of thermal treatment(85°C),1000 h of damp heat test(85°C&85%RH),and 250 cycles of thermal cycling test(−40 to 85°C),the devices maintain 92.6%,85.8%,and 96.1%of their initial efficiencies,respectively.
文摘Solar cells and other renewable energy sources are crucial in today's world where sustainability and environmental consciousness is at peak.Because of this,creating the optimal capacity is a fair aim for the operators of such technologies.The transformation of solar energy into either electricity by means of photovoltaics or into useable fuel by means of photo electrochemical cells remained a primary objective for research organizations and development sectors.In this piece,we will take a look back at the history of solar cells and examine their progression through the generations.The significant aspects which have an impact on the solar cells' performance are also discussed.This article provides a comprehensive and in-depth overview of the important aspects that affect the solar cells' performance,as well as a discussion of the application of bio-inspired optimization algorithms to improve the parameters of solar cells.Reviewing critical factors and their optimization for solar cell performance enhancement is crucial.It helps identify key performance factors,understand limitations,and challenges,and identify effective optimization strategies.By evaluating trade-offs and synergies,it guides future research and informs industrial applications,leading to more efficient and sustainable solar cell technologies.
基金Project(51378503)supported by the National Natural Science Foundation of ChinaProject(2010G018-A-3)supported by Technology Research and Development Program of the Ministry of Railways,China
文摘Based on transient temperature field theory of heat conduction, the solar temperature field calculation model of U-shape sectioned high-speed railway cable-stayed bridge under actions of concrete beams and ballast was established. Using parametric programming language, finite element calculation modules considering climate conditions, bridge site, structure dimension and material thermophysical properties were compiled. Six standard day cycles with the strongest yearly radiation among the bridge sites were selected for sectional solar temperature field calculation and temperature distributions under different temperature-sensitive parameters were compared. The results show that under the influence of sunshine, U-shape section of the beam shows obvious nonlinear distribution characteristics and the maximum cross-section temperature difference is more than 21℃; the ballast significantly reduces sunshine temperature difference of the beam and temperature peak of the bottom margin lags with the increase of ballast thickness; the maximum cross-section vertical temperature gradient appears in summer while large transverse temperature difference appears in winter.
文摘The paper reported a theoretical study on the photoconductivity of a bifacial silicon solar cell under polychromatic illumination and a constant magnetic field effect. By use of the continuity equation in the base of the solar cell maintained in a constant temperature at 300 K, an expression of the excess minority carriers’ density was determined according to the applied magnetic field, the base depth and the junction recombination velocity. From the expression of the minority carriers’ density, the photoconductivity of the solar cell was deduced and which allowed us to predict some recombination phenomena, the use of such solar cell in optoelectronics. The profile of the photoconductivity also permitted us to utilize a linear model in order to determine an electrical capacitance that varied with magnetic field.
基金We thank the National Key Research and Development Program of China(2017YFA0206600)the National Natural Science Foundation of China(51773045,21772030,51922032 and 21961160720)for financial support.
文摘Here we demonstrate a room-temperature drop-coating method for MAPbI_(3) films.By using low-boiling-point solvent,high-quality MAPbI_(3) films were made by simply casting a drop of solution onto the substrate at room temperature.This approach took advantage of the synergistic effect of good wettability and volatility of the solvent,enabling high nuclei density and compact film at room temperature.The crystal growth in different solvents was in-situ observed by using optical microscope,which helped us to understand the mechanism for the formation of different film morphology.Perovskite solar cells gave a PCE of 18.21%.
基金Project supported by the National High Technology Research and Development Program of China (Grant No. 2009AA05Z422), the National Basic Research Program of China (Grant Nos. 2011CBA00705, 2011CBA00706, and 2011CBA00707), and the Natural Science Foundation of Tianjin (Grant No. 08JCZDJC22200).
文摘This paper identifies the contributions of p-a-SiC:H layers and i-a-Si:H layers to the open circuit voltage of p-i-n type a-Si:H solar cells deposited at a low temperature of 125℃. We find that poor quality p-a-SiC:H films under regular conditions lead to a restriction of open circuit voltage although the band gap of the i-layer varies widely. A significant improvement in open circuit voltage has been obtained by using high quality p-~SiC:H films optimized at the "low-power regime" under low silane flow rates and high hydrogen dilution conditions.
文摘In static regime with polychromatic illumination, using the expression of the solar cell capacitance to determine the silicon solar cell capacitance C<sub>0</sub>(T) in short-circuit, is the purpose of this article. The expression of the excess minority carries density δ(x) from the continuity equation. The expression of δ(x) is used to determine the photovoltage expression. The capacitance efficiency dependence on X<sub>cc</sub>(T) is studied. X<sub>cc</sub>(T) is the abscissa of the maximum of δ(x).
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61574038 and 61674038)the Natural Science Foundation of Fujian Province,China(Grant No.2014J05073)
文摘The effect of the deposition temperature of the buffer layer In_2S_3 on the band alignment of CZTS/In_2S_3 heterostructures and the solar cell performance have been investigated.The In_2S_3 films are prepared by thermal evaporation method at temperatures of 30,100,150,and 200 ℃,respectively.By using x-ray photoelectron spectroscopy(XPS),the valence band offsets(VBO) are determined to be-0.28 ±0.1,-0.28 ±0.1,-0.34 ±0.1,and-0.42 ±0.1 eV for the CZTS/In_2S_3heterostructures deposited at 30,100,150,and 200 ℃,respectively,and the corresponding conduction band offsets(CBO)are found to be 0.3 ±0.1,0.41 ±0.1,0.22±0.1,and 0.01 ±0.1 eV,respectively.The XPS study also reveals that interdiffusion of In and Cu occurs at the interface of the heterostructures,which is especially serious at 200 ℃ leading to large amount of interface defects or the formation of CuInS_2 phase at the interface.The CZTS solar cell with the buffer layer In_2S_3 deposited at 150 ℃ shows the best performance due to the proper CBO value at the heterostructure interface and the improved crystal quality of In_2S_3 film induced by the appropriate deposition temperature.The device prepared at 100 ℃presents the poorest performance owing to too high a value of CBO.It is demonstrated that the deposition temperature is a crucial parameter to control the quality of the solar cells.
基金Funded by the National Natural Science Foundation of China(61366004)the Research Fund for the Doctoral Program of Higher Education(20123601110006)the Jiangxi Provincial Department of Education(KJLD13008)
文摘In order to enhance the p-type doping concentration in the LBSF, boron was added into the aluminum paste and boron doped local back surface field(B-LBSF) was successfully fabricated in this work. Through boron doping in the LBSF, much higher doping concentration was observed for the B-LBSF over the Al-LBSF. Higher doping concentration in the LBSF is expected to lead to better rear passivation and lower rear contact resistance. Based on one thousand pieces of solar cells for each type, it was found that the rear passivated crystalline silicon solar cells with B-LBSF showed statistical improvement in their photovoltaic properties over those with Al-LBSF.
文摘In this paper, a theory on the determination of the diffusion coefficient of excess minority carriers in the base of a silicon solar cell is presented. The diffusion coefficient expression has been established and is related to both frequency modulation and applied magnetic field;the study is then carried out using the impedance spectroscopy method and Bode diagrams. From the diffusion coefficient, we deduced the diffusion length and the minority carriers’ mobility. Electric parameters were derived from the diffusion coefficient equivalent circuits.
文摘The ac recombination velocity of the excess minority carriers, in the back surface of a silicon solar cell with a vertical junction connected in series, is developed through Einstein’s law giving the diffusion coefficient of minority carriers according to temperature, through mobility. The frequency spectrum of both, amplitude and phase, are produced for the diffusion coefficient and the recombination velocity in the rear face, in order to identify the parameters of equivalent electric models.
文摘The aim of this work is to present a theoretical study of external magnetic field effect on a bifacial silicon solar cell’s electrical parameters (peak power, fill factor and load resistance) using the J-V and P-V characteristics. After the resolution of the magneto transport equation and continuity equation of excess minority carriers in the base of the bifacial silicon solar cell under multispectral illumination, the photo-current density and the photovoltage are determined and the J-V and P-V curves are plotted. Using simultaneously the J-V and P-V curves, we determine, according to magnetic field intensity, the peak photocurrent density, the peak photovoltage, the peak electric power, the fill factor and the load resistance at the peak power point. The numerical data show that the solar cell’s peak power decreases with magnetic field intensity while the fill factor and the load resistance increase.
文摘The aim of this work is to investigate, with a three-dimensional steady-state approach, the effect of the incidence angle of a magnetic field on the performance of a polycrystalline silicon solar cell under multispectral illumination. The magneto-transport and continuity equations of excess minority carriers are solved to find the expression of the density of excess minority carriers and the related electrical parameters, such as the photocurrent density, the photovoltage and the electric power, of a grain of the polycrystalline silicon solar cell. The influence of the incidence angle of the magnetic field on the diffusion coefficient, the short-circuit photocurrent density, the open-circuit photovoltage and the electric power-photovoltage is studied. Then, the curves of the electric power-photovoltage is used to find the maximum electric power allowing to calculate, according to the incidence angle of the magnetic field, the fill factor and the conversion efficiency. The study has shown that the increase of the incidence angle of the magnetic field from 0 rad to π/2 rad, can reduce the degradation of the performance of solar cells.
文摘The temperature of a solar cell subjected to the incident global solar radiation as a function of the local day time is determined. A heat balance equation is solved considering the heat losses due to convection and thermal radiation. The cell efficiency is estimated as a measure of its performance. The results reveal that the temperature within the cell attains significant values. Nevertheless, the temperature dependence of its efficiency along the day time is not pronouncing. It slightly decreases with temperature.
基金supported by 973 Program of China (2014CB643506 and 2013CB922104)the NSFC (21173091 and 61205034)
文摘In recent years perovskite solar cells have attracted an increasing scientific and technological interest in the scientific community. It is important to know that the temperature is one of the factors which have a strong effect on the efficiency of perovskite solar cell. This study communicates a temperature analysis on the pho- tovoltaic parameters of CH3NH3Pbl3-based perovskite solar cell in a broad interval from 80 to 360 K. Strong temperature-dependent photovoltaic effects have been observed in the type of solar cell, which could be mainly attributed to CH3NH3PbI3, showing a ferroelectric-paraelectric phase transition at low temperature (T 〈 160 K). An increase in temperature over the room temperature decreased the perovskite solar cell performance and reduced its efficiency from 16Z to 9%. The investigation with electronic impedance spectroscopy reveals that at low temperature (T 〈 120 K) the charge transport layer limits the device performance, while at high temperature (T 〉 200 K), the interfacial charge recombination becomes the dominant factor.