Fiber-reinforced composites possess anisotropic mechanical and heat transfer properties due to their anisotropic fibers and structure distribution.In C/Si C composites,the out-of-plane thermal conductivity has mainly ...Fiber-reinforced composites possess anisotropic mechanical and heat transfer properties due to their anisotropic fibers and structure distribution.In C/Si C composites,the out-of-plane thermal conductivity has mainly been studied,whereas the in-plane thermal conductivity has received less attention due to their limited thickness.展开更多
Formal cross-dimerization of two different strained rings represents an innovative strategy toward specific ring systems that are otherwise inaccessible.Yet,formidable challenges remain in controlling the reactivity a...Formal cross-dimerization of two different strained rings represents an innovative strategy toward specific ring systems that are otherwise inaccessible.Yet,formidable challenges remain in controlling the reactivity and site-selectivity.Herein,we realized the reversal of site-selectivity in formal crossdimerization of benzocyclobutenones(BCBs)and silacyclobutanes(SCBs)by development of a nickel/magnesium synergistic catalytic system,in which the C(sp3)−C(carbonyl)bond of BCBs was exclusively cleaved,providing previously inaccessible eight-membered benzosilacycles.The catalytic cycle,the origin of this unconventional site-selectivity,and the role of MgCl2 have explicitly been elucidated by density functional theory calculations.Combined experimental and computational studies have clearly illustrated that the C1-C8 cleavage selectivity of BCBs in our reaction are mainly attributed to both the steric hindrance by introduction of substituents at the C3-and the proper choice of the Ni/Mg synergistic catalytic system.展开更多
Monolithic hybrid halide perovskite/crystalline silicon(c-Si)tandem solar cells have demonstrated their great potential to surpass the theoretical efficiency limit of single-junction devices.However,the stability of p...Monolithic hybrid halide perovskite/crystalline silicon(c-Si)tandem solar cells have demonstrated their great potential to surpass the theoretical efficiency limit of single-junction devices.However,the stability of perovskite sub-cells is inferior to that of the c-Si solar cells that have been commercialized,casting serious doubt about the lifetime of the entire device.During device operation,light and heat are inevitable,which requires special attention.Herein,we review the current understandings of the intrinsic stability of perovskite/c-Si tandems upon light and/or heat aging.First,we summarize the recent understandings regarding light facilitated ion migration,materials decomposition,and phase segregation.In addition,the reverse bias effect on the stability of tandem modules caused by uneven illumination is discussed.Second,this review also summarizes the thermalinduced degradation and mismatch issue,which underlines the system design of perovskite/c-Si tandems.Third,recent strategies to improve the intrinsic stability of perovskite/c-Si tandems under light and/or heat are reviewed,such as composition engineering,crystallinity enhancement,interface modification,material optimization,and device structure modification.At last,we present several potential research directions that have been overlooked,and hope those are helpful for future research on perovskite based tandem solar cells.展开更多
Boron-oxygen defects can cause serious lightinduced degradation （LID） of commercial solar cells based on the boron-doped crystalline silicon （c-Si）, which are formed under the injection of excess carriers induced ...Boron-oxygen defects can cause serious lightinduced degradation （LID） of commercial solar cells based on the boron-doped crystalline silicon （c-Si）, which are formed under the injection of excess carriers induced either by illumination or applying forward bias. In this contribution, we have demonstrated that the passivation process of boron-oxygen defects can be induced by applying forward bias for a large quantity of solar cells, which is much more economic than light illumination. We have used this strategy to trigger the passivation process of batches of aluminum back surface field （A1-BSF） solar cells and passivated emitter and rear contact （PERC） solar cells. Both kinds of the treated solar cells show high stability in efficiency and suffer from very little LID under further illumination at room temperature. This technology is of significance for the suppression of LID of c-Si solar cells for the industrial manufacture.展开更多
In a recent previous work, we proposed a rotating polarizer-analyzer ellipsometer (RPAE) in which the two elements are rotating synchronously in the same direction with a speed ratio 1:3. We applied this technique to ...In a recent previous work, we proposed a rotating polarizer-analyzer ellipsometer (RPAE) in which the two elements are rotating synchronously in the same direction with a speed ratio 1:3. We applied this technique to bulk samples. In this work, we present theoretically the characterization of 100 nm SiO2 thin film using this spectroscopic RPAE. We assume a structure consisting of air (ambient)/SiO2 (thin film)/c-Si (substrate). The ellipsometric parameters ψ and Δ are calculated when a clean signal is received by the detector and when a hypothetical noise is imposed on this signal. The film thickness and the optical constants of the film are calculated for the noisy signal in the spectrum range 200 - 800 nm. The results are compared with the proposed thickness and with the accepted values for SiO2 optical constants.展开更多
We put forward an n-ZnO/p-Si heterojunction solar cell model based on AFORS-HET simulations and provide experimental support in this article.ZnO：B（B-doped ZnO） thin films deposited by metal-organic chemical vapor d...We put forward an n-ZnO/p-Si heterojunction solar cell model based on AFORS-HET simulations and provide experimental support in this article.ZnO：B（B-doped ZnO） thin films deposited by metal-organic chemical vapor deposition（MOCVD） are planned to act as electrical emitter layer on p-type c-Si substrate for photovoltaic applications.We investigate the effects of thickness,buffer layer,ZnO：B affinity and work function of electrodes on performances of solar cells through computer simulations using AFORS-HET software package.The energy conversion efficiency of the ZnO：B（n）/ZnO/c-Si（p） solar cell can achieve 17.16%（V（oc）：675.8 mV,J（sc）：30.24 mA/cm^2,FF：83.96%） via simulation.On a basis of optimized conditions in simulation,we carry out some experiments,which testify that the ZnO buffer layer of 20 nm contributes to improving performances of solar cells.The influences of growth temperature,thickness and diborane（B2H6） flow rates are also discussed.We achieve an appropriate condition for the fabrication of the solar cells using the MOCVD technique.The obtained conversion efficiency reaches2.82%（V（oc）：294.4 mV,J（sc）：26.108 mA/cm^2,FF：36.66%）.展开更多
Crystalline silicon（c-Si） is unambiguously the most important semiconductor that underpins the development of modern microelectronics and optoelectronics, though the rigid and brittle nature of bulk c-Si makes it di...Crystalline silicon（c-Si） is unambiguously the most important semiconductor that underpins the development of modern microelectronics and optoelectronics, though the rigid and brittle nature of bulk c-Si makes it difficult to implement directly for stretchable applications. Fortunately, the one-dimensional（1 D） geometry, or the line-shape, of Si nanowire（SiNW） can be engineered into elastic springs, which indicates an exciting opportunity to fabricate highly stretchable 1 D c-Si channels. The implementation of such line-shape-engineering strategy demands both a tiny diameter of the SiNWs, in order to accommodate the strains under large stretching, and a precise growth location, orientation and path control to facilitate device integration. In this review, we will first introduce the recent progresses of an in-plane self-assembly growth of SiNW springs, via a new in-plane solid-liquidsolid（IPSLS） mechanism, where mono-like but elastic SiNW springs are produced by surface-running metal droplets that absorb amorphous Si thin film as precursor. Then, the critical growth control and engineering parameters, the mechanical properties of the SiNW springs and the prospects of developing c-Si based stretchable electronics, will be addressed. This efficient line-shape-engineering strategy of SiNW springs, accomplished via a low temperature batch-manufacturing, holds a strong promise to extend the legend of modern Si technology into the emerging stretchable electronic applications, where the high carrier mobility, excellent stability and established doping and passivation controls of c-Si can be well inherited.展开更多
Crystalline silicon (c-Si) solar cells have the lion share in world PV market. Solar cells made from crystalline silicon have lower conversion efficiency, hence optimization of each process steps are very important. A...Crystalline silicon (c-Si) solar cells have the lion share in world PV market. Solar cells made from crystalline silicon have lower conversion efficiency, hence optimization of each process steps are very important. Achieving low-cost photovoltaic energy in the coming years will depend on the development of third-generation solar cells. Given the trend towards these Si materials, the most promising selective emitter methods are identified to date. Current industrial monocrystalline Cz Si solar cells based on screen-printing technology for contact formation and homogeneous emitter have an efficiency potential of around 18.4%. Limitations at the rear side by the fully covering Al-BSF can be changed by selective emitter designs allowing a decoupling and separate optimization of the metallised and non-metallised areas. Several selective emitter concepts that are already in industrial mass production or close to it are presented, and their specialties and status concerning cell performance are demonstrated. Key issues that are considered here are the cost-effectiveness, added complexity, additional benefits, reliability and efficiency potential of each selective emitter tech- niques.展开更多
Hydrogen is a ubiquitous element in semiconductor processing and particularly in amorphous and microcrystalline silicon where it plays a crucial role in the growth processes as well as in the material properties. Beca...Hydrogen is a ubiquitous element in semiconductor processing and particularly in amorphous and microcrystalline silicon where it plays a crucial role in the growth processes as well as in the material properties. Because of its low mass it can easily diffuse through the silicon network and leads to the passivation of dangling bonds but it may also play a role in the stabilization of metastable defects. Thus a lot of work has been devoted to the study of hydrogen diffusion, bonding and structure in disordered semiconductors. The sequence, deposition-exposure to H plasma-deposition was used to fabricate the microcrystalline emitter. A proper atomic H pretreatment of c-Si surface before depositions i layer was expected to clean the surface and passivatates the surface states, as a result improing the device parameters. In this study, H2 pretreatment of c-si surface was used at different time, power and temperature. It is found that a proper H pretreatment improves passivation of c-si surface and improves the device parameters by AFM and testing I-V.展开更多
SiNx/SiOx passivation and double side P-diffusion gettering treatment have been used for the fabrication of c-Si solar cells. The solar cells fabricated have high open circuit voltage and short circuit current after t...SiNx/SiOx passivation and double side P-diffusion gettering treatment have been used for the fabrication of c-Si solar cells. The solar cells fabricated have high open circuit voltage and short circuit current after the double P-diffusion treatment. In addition to better surface passivation effect, SiNx/SiOx layer has lower reflectivity in long wavelength range than conventional SiNx film. As a consequence, such solar cells exhibit higher conversion efficiency and better internal quantum efficiency, compared with conventional c-Si solar cells.展开更多
Precursor concentration dependences of growth rate, doping concentration and surface morphology have been investigated in the epitaxial growth of 4H-SiC（0001） epilayers with horizontal hot-wall CVD system using vari...Precursor concentration dependences of growth rate, doping concentration and surface morphology have been investigated in the epitaxial growth of 4H-SiC（0001） epilayers with horizontal hot-wall CVD system using various precursor concentrations under constant C/Si ratio. Form the experimental data it is found that silicon cluster which is formed through gas phase nucleation plays an important role in controlling the doping concentration and epitaxial growth rate of the silicon carbide. It was observed that the concentration of silicon clusters cannot reach the equilibrium value in the process by using a low Sill4 concentration, and this phenomenon has not been reported by others.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52276086 and 52130604)the Basic Research Program of China(Grant No.514010303-102)the K.C.Wong Education Foundation。
文摘Fiber-reinforced composites possess anisotropic mechanical and heat transfer properties due to their anisotropic fibers and structure distribution.In C/Si C composites,the out-of-plane thermal conductivity has mainly been studied,whereas the in-plane thermal conductivity has received less attention due to their limited thickness.
基金grateful for financial support from the National Natural Science Foundation of China(grant nos.22071114,22022103,21871146,22122104,22193012,22188101,and 21933004)the National Key Research and Development Program of China(grant nos.2019YFA0210500 and 2021YFF0701700)+1 种基金the Frontiers Science Center for New Organic Matter,Nankai University(grant no.63181206)the Fundamental Research Funds for the Central Universities and Nankai University.
文摘Formal cross-dimerization of two different strained rings represents an innovative strategy toward specific ring systems that are otherwise inaccessible.Yet,formidable challenges remain in controlling the reactivity and site-selectivity.Herein,we realized the reversal of site-selectivity in formal crossdimerization of benzocyclobutenones(BCBs)and silacyclobutanes(SCBs)by development of a nickel/magnesium synergistic catalytic system,in which the C(sp3)−C(carbonyl)bond of BCBs was exclusively cleaved,providing previously inaccessible eight-membered benzosilacycles.The catalytic cycle,the origin of this unconventional site-selectivity,and the role of MgCl2 have explicitly been elucidated by density functional theory calculations.Combined experimental and computational studies have clearly illustrated that the C1-C8 cleavage selectivity of BCBs in our reaction are mainly attributed to both the steric hindrance by introduction of substituents at the C3-and the proper choice of the Ni/Mg synergistic catalytic system.
基金supported by the National Natural Science Foundation of China(Grant Nos.21975028,22005035,U21A20172,and 22011540377)Natural Science Funds of the Beijing Municipality(Grant No.JQ19008)+1 种基金China Postdoctoral Science Foundation(Grant No.2021M700400)Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘Monolithic hybrid halide perovskite/crystalline silicon(c-Si)tandem solar cells have demonstrated their great potential to surpass the theoretical efficiency limit of single-junction devices.However,the stability of perovskite sub-cells is inferior to that of the c-Si solar cells that have been commercialized,casting serious doubt about the lifetime of the entire device.During device operation,light and heat are inevitable,which requires special attention.Herein,we review the current understandings of the intrinsic stability of perovskite/c-Si tandems upon light and/or heat aging.First,we summarize the recent understandings regarding light facilitated ion migration,materials decomposition,and phase segregation.In addition,the reverse bias effect on the stability of tandem modules caused by uneven illumination is discussed.Second,this review also summarizes the thermalinduced degradation and mismatch issue,which underlines the system design of perovskite/c-Si tandems.Third,recent strategies to improve the intrinsic stability of perovskite/c-Si tandems under light and/or heat are reviewed,such as composition engineering,crystallinity enhancement,interface modification,material optimization,and device structure modification.At last,we present several potential research directions that have been overlooked,and hope those are helpful for future research on perovskite based tandem solar cells.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant Nos. 51532007, 61574124 and 51472219）, the Program for Innovative Research Team in University of Ministry of Education of China （IRT13R54）, and State Key Laboratory of Optoelectronic Materials and Technologies （Sun Yat-sen University）.
文摘Boron-oxygen defects can cause serious lightinduced degradation （LID） of commercial solar cells based on the boron-doped crystalline silicon （c-Si）, which are formed under the injection of excess carriers induced either by illumination or applying forward bias. In this contribution, we have demonstrated that the passivation process of boron-oxygen defects can be induced by applying forward bias for a large quantity of solar cells, which is much more economic than light illumination. We have used this strategy to trigger the passivation process of batches of aluminum back surface field （A1-BSF） solar cells and passivated emitter and rear contact （PERC） solar cells. Both kinds of the treated solar cells show high stability in efficiency and suffer from very little LID under further illumination at room temperature. This technology is of significance for the suppression of LID of c-Si solar cells for the industrial manufacture.
文摘In a recent previous work, we proposed a rotating polarizer-analyzer ellipsometer (RPAE) in which the two elements are rotating synchronously in the same direction with a speed ratio 1:3. We applied this technique to bulk samples. In this work, we present theoretically the characterization of 100 nm SiO2 thin film using this spectroscopic RPAE. We assume a structure consisting of air (ambient)/SiO2 (thin film)/c-Si (substrate). The ellipsometric parameters ψ and Δ are calculated when a clean signal is received by the detector and when a hypothetical noise is imposed on this signal. The film thickness and the optical constants of the film are calculated for the noisy signal in the spectrum range 200 - 800 nm. The results are compared with the proposed thickness and with the accepted values for SiO2 optical constants.
基金Project supported by the State Key Development Program for Basic Research of China(Nos.2011CBA00706,2011CBA00707)the Tianjin Applied Basic Research Project and Cutting-Edge Technology Research Plan(No.13JCZDJC26900)+2 种基金the Tianjin Major Science and Technology Support Project(No.11TXSYGX22100)the National High Technology Research and Development Program of China(No.2013AA050302)the Fundamental Research Funds for the Central Universities(No.65010341)
文摘We put forward an n-ZnO/p-Si heterojunction solar cell model based on AFORS-HET simulations and provide experimental support in this article.ZnO：B（B-doped ZnO） thin films deposited by metal-organic chemical vapor deposition（MOCVD） are planned to act as electrical emitter layer on p-type c-Si substrate for photovoltaic applications.We investigate the effects of thickness,buffer layer,ZnO：B affinity and work function of electrodes on performances of solar cells through computer simulations using AFORS-HET software package.The energy conversion efficiency of the ZnO：B（n）/ZnO/c-Si（p） solar cell can achieve 17.16%（V（oc）：675.8 mV,J（sc）：30.24 mA/cm^2,FF：83.96%） via simulation.On a basis of optimized conditions in simulation,we carry out some experiments,which testify that the ZnO buffer layer of 20 nm contributes to improving performances of solar cells.The influences of growth temperature,thickness and diborane（B2H6） flow rates are also discussed.We achieve an appropriate condition for the fabrication of the solar cells using the MOCVD technique.The obtained conversion efficiency reaches2.82%（V（oc）：294.4 mV,J（sc）：26.108 mA/cm^2,FF：36.66%）.
基金supported by the National Basic Research 973 Program(No.2014CB921101)the National Natural Science Foundation of China(No.61674075)+5 种基金the National Key Research and Development Program of China(No.2017YFA0205003)the Jiangsu Excellent Young Scholar Program(No.BK20160020)the Scientific and Technological Support Program in Jiangsu Province(No.BE2014147-2)the Jiangsu Shuangchuang Team's Personal Programthe Fundamental Research Funds for the Central Universitiesthe China Scholarship Council and the Postgraduate Program of Jiangsu Province(No.KYZZ160052)
文摘Crystalline silicon（c-Si） is unambiguously the most important semiconductor that underpins the development of modern microelectronics and optoelectronics, though the rigid and brittle nature of bulk c-Si makes it difficult to implement directly for stretchable applications. Fortunately, the one-dimensional（1 D） geometry, or the line-shape, of Si nanowire（SiNW） can be engineered into elastic springs, which indicates an exciting opportunity to fabricate highly stretchable 1 D c-Si channels. The implementation of such line-shape-engineering strategy demands both a tiny diameter of the SiNWs, in order to accommodate the strains under large stretching, and a precise growth location, orientation and path control to facilitate device integration. In this review, we will first introduce the recent progresses of an in-plane self-assembly growth of SiNW springs, via a new in-plane solid-liquidsolid（IPSLS） mechanism, where mono-like but elastic SiNW springs are produced by surface-running metal droplets that absorb amorphous Si thin film as precursor. Then, the critical growth control and engineering parameters, the mechanical properties of the SiNW springs and the prospects of developing c-Si based stretchable electronics, will be addressed. This efficient line-shape-engineering strategy of SiNW springs, accomplished via a low temperature batch-manufacturing, holds a strong promise to extend the legend of modern Si technology into the emerging stretchable electronic applications, where the high carrier mobility, excellent stability and established doping and passivation controls of c-Si can be well inherited.
文摘Crystalline silicon (c-Si) solar cells have the lion share in world PV market. Solar cells made from crystalline silicon have lower conversion efficiency, hence optimization of each process steps are very important. Achieving low-cost photovoltaic energy in the coming years will depend on the development of third-generation solar cells. Given the trend towards these Si materials, the most promising selective emitter methods are identified to date. Current industrial monocrystalline Cz Si solar cells based on screen-printing technology for contact formation and homogeneous emitter have an efficiency potential of around 18.4%. Limitations at the rear side by the fully covering Al-BSF can be changed by selective emitter designs allowing a decoupling and separate optimization of the metallised and non-metallised areas. Several selective emitter concepts that are already in industrial mass production or close to it are presented, and their specialties and status concerning cell performance are demonstrated. Key issues that are considered here are the cost-effectiveness, added complexity, additional benefits, reliability and efficiency potential of each selective emitter tech- niques.
基金This project was financially supported by the Natural Science Foundation of Hebei Province, China (No.F2005000073).
文摘Hydrogen is a ubiquitous element in semiconductor processing and particularly in amorphous and microcrystalline silicon where it plays a crucial role in the growth processes as well as in the material properties. Because of its low mass it can easily diffuse through the silicon network and leads to the passivation of dangling bonds but it may also play a role in the stabilization of metastable defects. Thus a lot of work has been devoted to the study of hydrogen diffusion, bonding and structure in disordered semiconductors. The sequence, deposition-exposure to H plasma-deposition was used to fabricate the microcrystalline emitter. A proper atomic H pretreatment of c-Si surface before depositions i layer was expected to clean the surface and passivatates the surface states, as a result improing the device parameters. In this study, H2 pretreatment of c-si surface was used at different time, power and temperature. It is found that a proper H pretreatment improves passivation of c-si surface and improves the device parameters by AFM and testing I-V.
基金Project supported by the National Natural Science Foundation of China(Nos.61474104,61504131)
文摘SiNx/SiOx passivation and double side P-diffusion gettering treatment have been used for the fabrication of c-Si solar cells. The solar cells fabricated have high open circuit voltage and short circuit current after the double P-diffusion treatment. In addition to better surface passivation effect, SiNx/SiOx layer has lower reflectivity in long wavelength range than conventional SiNx film. As a consequence, such solar cells exhibit higher conversion efficiency and better internal quantum efficiency, compared with conventional c-Si solar cells.
文摘Precursor concentration dependences of growth rate, doping concentration and surface morphology have been investigated in the epitaxial growth of 4H-SiC（0001） epilayers with horizontal hot-wall CVD system using various precursor concentrations under constant C/Si ratio. Form the experimental data it is found that silicon cluster which is formed through gas phase nucleation plays an important role in controlling the doping concentration and epitaxial growth rate of the silicon carbide. It was observed that the concentration of silicon clusters cannot reach the equilibrium value in the process by using a low Sill4 concentration, and this phenomenon has not been reported by others.
