Pub Date : 1994-12-05DOI: 10.1109/WCPEC.1994.520195
T. Ciszek, T. Wang, R. Burrows, T. Bekkadahl, M. Symko, J. Webb
We studied the effects of Si growth in atmospheres containing N/sub 2/ on minority charge carrier lifetime /spl tau/ using a high-purity, induction-heated, float-zone (FZ) crystal growth method. Ingots were grown in ambients that ranged from pure argon (99.9995%) to pure N/sub 2/ (99.999%). /spl tau/ was measured as a function of position along the ingots using the ASTM F28-75 photoconductive decay (PCD) method. We found that Ga-doped, multicrystalline silicon ingot growth in a partial or total nitrogen ambient has a negligible effect on minority charge carrier lifetime and no significant grain boundary passivation effect. Values of 40 /spl mu/s
{"title":"Effect of nitrogen doping on microdefects and minority charge carrier lifetime of high-purity, dislocation-free and multicrystalline silicon","authors":"T. Ciszek, T. Wang, R. Burrows, T. Bekkadahl, M. Symko, J. Webb","doi":"10.1109/WCPEC.1994.520195","DOIUrl":"https://doi.org/10.1109/WCPEC.1994.520195","url":null,"abstract":"We studied the effects of Si growth in atmospheres containing N/sub 2/ on minority charge carrier lifetime /spl tau/ using a high-purity, induction-heated, float-zone (FZ) crystal growth method. Ingots were grown in ambients that ranged from pure argon (99.9995%) to pure N/sub 2/ (99.999%). /spl tau/ was measured as a function of position along the ingots using the ASTM F28-75 photoconductive decay (PCD) method. We found that Ga-doped, multicrystalline silicon ingot growth in a partial or total nitrogen ambient has a negligible effect on minority charge carrier lifetime and no significant grain boundary passivation effect. Values of 40 /spl mu/s</spl tau/<100 /spl mu/s were typical regardless of ambient. For dislocation-free (DF) growth, the degradation of /spl tau/ is minimal and /spl tau/ values above 1000 /spl mu/s are obtained if the amount of N/sub 2/ in the purge gas is below the level at which nitride compounds form in the melt and disrupt DF growth.","PeriodicalId":20517,"journal":{"name":"Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74410955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1994-12-05DOI: 10.1109/WCPEC.1994.520120
C. Eberspacher, C.F. Gay, P. Moskowitz
Recycling end-of-life cadmium telluride (CdTe) photovoltaic (PV) modules may enhance the competitive advantage of CdTe PV in the marketplace, but the experiences of industries with comparable environmental, health and safety challenges suggest that collection and recycling costs can impose significant economic burdens. Customer cooperation and pending changes to US Federal Law may improve recycling economics.
{"title":"Strategies for recycling CdTe photovoltaic modules","authors":"C. Eberspacher, C.F. Gay, P. Moskowitz","doi":"10.1109/WCPEC.1994.520120","DOIUrl":"https://doi.org/10.1109/WCPEC.1994.520120","url":null,"abstract":"Recycling end-of-life cadmium telluride (CdTe) photovoltaic (PV) modules may enhance the competitive advantage of CdTe PV in the marketplace, but the experiences of industries with comparable environmental, health and safety challenges suggest that collection and recycling costs can impose significant economic burdens. Customer cooperation and pending changes to US Federal Law may improve recycling economics.","PeriodicalId":20517,"journal":{"name":"Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74585803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1994-12-05DOI: 10.1109/WCPEC.1994.519960
K. Mitchell, R. King, T. Jester, M. Mcgraw
New developments in all areas of Czochralski (Cz) silicon photovoltaic (PV) technology, from Si feedstock costs, to Cz crystal growth, to the introduction of wire saw technology, to novel cell designs and processing provide the basis for Cz Si achieving module costs in the $2/Wp range. This paper describes the re-formation of Cz manufacturing at Siemens Solar to achieve these lower costs, ranging from process improvements and equipment upgrades to changes in cell and module design. Continued efforts, building upon the improvements introduced in PVMat Phase 2A, will produce improved manufacturing with higher throughputs and yields at lower costs.
{"title":"The reformation of Cz Si photovoltaics","authors":"K. Mitchell, R. King, T. Jester, M. Mcgraw","doi":"10.1109/WCPEC.1994.519960","DOIUrl":"https://doi.org/10.1109/WCPEC.1994.519960","url":null,"abstract":"New developments in all areas of Czochralski (Cz) silicon photovoltaic (PV) technology, from Si feedstock costs, to Cz crystal growth, to the introduction of wire saw technology, to novel cell designs and processing provide the basis for Cz Si achieving module costs in the $2/Wp range. This paper describes the re-formation of Cz manufacturing at Siemens Solar to achieve these lower costs, ranging from process improvements and equipment upgrades to changes in cell and module design. Continued efforts, building upon the improvements introduced in PVMat Phase 2A, will produce improved manufacturing with higher throughputs and yields at lower costs.","PeriodicalId":20517,"journal":{"name":"Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75902621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1994-12-05DOI: 10.1109/WCPEC.1994.520222
J. Wohlgemuth, T. Koval, D. Whitehouse, J. Creager
It is important to maximize the amount of sunlight optically coupled into a solar cell. The usual approach to evaluate optical coupling is to fabricate solar cells and then to measure their performance under standard test conditions, using the short circuit current as the figure of merit. This approach suffers from several short comings, including spectral mismatch errors in the measurement and process induced variations in the performance. This paper presents an improved methodology for evaluating optical coupling, based on measuring the reflectance of sample surfaces as a function of wavelength. The effect of using this surface geometry on a particular cell can then be calculated using values of previously measured internal quantum efficiency for the cell technology selected. Data on a variety of surface texture treatments are presented.
{"title":"Evaluating the effectiveness of optical coupling techniques","authors":"J. Wohlgemuth, T. Koval, D. Whitehouse, J. Creager","doi":"10.1109/WCPEC.1994.520222","DOIUrl":"https://doi.org/10.1109/WCPEC.1994.520222","url":null,"abstract":"It is important to maximize the amount of sunlight optically coupled into a solar cell. The usual approach to evaluate optical coupling is to fabricate solar cells and then to measure their performance under standard test conditions, using the short circuit current as the figure of merit. This approach suffers from several short comings, including spectral mismatch errors in the measurement and process induced variations in the performance. This paper presents an improved methodology for evaluating optical coupling, based on measuring the reflectance of sample surfaces as a function of wavelength. The effect of using this surface geometry on a particular cell can then be calculated using values of previously measured internal quantum efficiency for the cell technology selected. Data on a variety of surface texture treatments are presented.","PeriodicalId":20517,"journal":{"name":"Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77475241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1994-12-05DOI: 10.1109/WCPEC.1994.521648
S. Messenger, M. Xapsos, G. Summers, E. Burke
The use of a Co/sup 60/ gamma ray source to measure radiation-induced degradation in advanced space photovoltaic materials is described. The background theory is presented and is applied to both n/p and p/n InP solar cells. Both Co/sup 60/ gamma ray and 1 MeV electron irradiation data are presented which correlate together well using the theory. The approach is applicable to any cell technology.
{"title":"Co/sup 60/ gamma ray irradiations of solar cells: a new way to predict space radiation damage","authors":"S. Messenger, M. Xapsos, G. Summers, E. Burke","doi":"10.1109/WCPEC.1994.521648","DOIUrl":"https://doi.org/10.1109/WCPEC.1994.521648","url":null,"abstract":"The use of a Co/sup 60/ gamma ray source to measure radiation-induced degradation in advanced space photovoltaic materials is described. The background theory is presented and is applied to both n/p and p/n InP solar cells. Both Co/sup 60/ gamma ray and 1 MeV electron irradiation data are presented which correlate together well using the theory. The approach is applicable to any cell technology.","PeriodicalId":20517,"journal":{"name":"Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77670902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1994-12-05DOI: 10.1109/WCPEC.1994.520173
K. Reiche, R. Preu, G. Kleiss, K. Bucher
The effect of advantageous placing when assembling solar cells or modules to PV modules or generating arrays respectively is investigated. The idea is to take advantage of thermal inhomogenities within a PV generating unit to reduce a possible mismatch between nonidentical components when operated at MPP (maximum power point). The cases of series and parallel connecting photovoltaic generating components are studied. The authors simulated the output of a cell production (or module production respectively) and estimated the effect on generator efficiency. As result, they found a possible gain in the energy output of up to 3% for the set-up of a PV array (parallel connected case) while the effect occurring within a module is negligible (series connected case). A simple rule for advantageous module placing within a PV array is formulated.
{"title":"Effects of advantageous placing of PV cells and modules in generating units","authors":"K. Reiche, R. Preu, G. Kleiss, K. Bucher","doi":"10.1109/WCPEC.1994.520173","DOIUrl":"https://doi.org/10.1109/WCPEC.1994.520173","url":null,"abstract":"The effect of advantageous placing when assembling solar cells or modules to PV modules or generating arrays respectively is investigated. The idea is to take advantage of thermal inhomogenities within a PV generating unit to reduce a possible mismatch between nonidentical components when operated at MPP (maximum power point). The cases of series and parallel connecting photovoltaic generating components are studied. The authors simulated the output of a cell production (or module production respectively) and estimated the effect on generator efficiency. As result, they found a possible gain in the energy output of up to 3% for the set-up of a PV array (parallel connected case) while the effect occurring within a module is negligible (series connected case). A simple rule for advantageous module placing within a PV array is formulated.","PeriodicalId":20517,"journal":{"name":"Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78126355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1994-12-05DOI: 10.1109/WCPEC.1994.520553
S. R. Kurtz, K. Emery, J. Olson
Accurate measurement techniques are essential to the advancement of photovoltaic device technologies. Measurements of multijunction, two-terminal devices (Ga/sub 0.5/In/sub 0.5/As/GaAs solar cells) are especially difficult because researchers need to be able to characterize the individual cells but are unable to connect directly to them. We describe a single-source simulator (with large-area filters) method for obtaining current-voltage (I-V) curves of both the individual cells and the tandem cell for arbitrary spectra. The filters used for the I-V measurements and for quantum efficiency (QE) measurements are somewhat different. Voltage biasing for QE measurements is useful when one cell is shunted or has a small reverse breakdown voltage, but is often unnecessary for Ill-V devices.
{"title":"Methods for analysis of two-functional, two-terminal photovoltaic devices","authors":"S. R. Kurtz, K. Emery, J. Olson","doi":"10.1109/WCPEC.1994.520553","DOIUrl":"https://doi.org/10.1109/WCPEC.1994.520553","url":null,"abstract":"Accurate measurement techniques are essential to the advancement of photovoltaic device technologies. Measurements of multijunction, two-terminal devices (Ga/sub 0.5/In/sub 0.5/As/GaAs solar cells) are especially difficult because researchers need to be able to characterize the individual cells but are unable to connect directly to them. We describe a single-source simulator (with large-area filters) method for obtaining current-voltage (I-V) curves of both the individual cells and the tandem cell for arbitrary spectra. The filters used for the I-V measurements and for quantum efficiency (QE) measurements are somewhat different. Voltage biasing for QE measurements is useful when one cell is shunted or has a small reverse breakdown voltage, but is often unnecessary for Ill-V devices.","PeriodicalId":20517,"journal":{"name":"Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79356864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1994-12-05DOI: 10.1109/WCPEC.1994.520075
F. Shinjo
In an attempt to promote the widespread introduction of photovoltaic power generation systems, it is necessary to achieve utility sales price-equivalent power generation costs through implemented system cost reduction. For this purpose, photovoltaic modules integrated with construction materials will be developed so that photovoltaic power generation module costs and installation work expenses can be substantially reduced by including them in the materials and general construction work costs.
{"title":"R&D of photovoltaic modules integrated with construction materials","authors":"F. Shinjo","doi":"10.1109/WCPEC.1994.520075","DOIUrl":"https://doi.org/10.1109/WCPEC.1994.520075","url":null,"abstract":"In an attempt to promote the widespread introduction of photovoltaic power generation systems, it is necessary to achieve utility sales price-equivalent power generation costs through implemented system cost reduction. For this purpose, photovoltaic modules integrated with construction materials will be developed so that photovoltaic power generation module costs and installation work expenses can be substantially reduced by including them in the materials and general construction work costs.","PeriodicalId":20517,"journal":{"name":"Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81638137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1994-12-05DOI: 10.1109/WCPEC.1994.519954
S. Wenham, M. Green, S. Edmiston, P. Campbell, L. Koschier, C. Honsberg, A. Sproul, D. Thorpe, Z. Shi, G. Heiser
Thin film crystalline silicon solar cells can only achieve high efficiencies if light trapping can be used to give a long optical path length, while simultaneously achieving near unity collection probabilities for all generated carriers. This necessitates a supporting substrate of a foreign material, with refractive index compatible with light trapping schemes for the silicon. The resulting inability to nucleate growth of crystalline silicon films of good crystallographic quality on such foreign substrates, prevents the achievement of high efficiency devices using conventional single junction solar cell structures. The parallel multijunction solar cell provides a new approach for achieving high efficiencies from very poor quality material, with near unity collection probabilities for all generated carriers achieved through appropriate junction spacing. Heavy doping is used to minimise the dark saturation current contribution from the layers, therefore allowing respectable voltages. The design strategy, corresponding advantages, theoretical predictions and experimental results are presented.
{"title":"Limits to the efficiency of silicon multilayer thin film solar cells","authors":"S. Wenham, M. Green, S. Edmiston, P. Campbell, L. Koschier, C. Honsberg, A. Sproul, D. Thorpe, Z. Shi, G. Heiser","doi":"10.1109/WCPEC.1994.519954","DOIUrl":"https://doi.org/10.1109/WCPEC.1994.519954","url":null,"abstract":"Thin film crystalline silicon solar cells can only achieve high efficiencies if light trapping can be used to give a long optical path length, while simultaneously achieving near unity collection probabilities for all generated carriers. This necessitates a supporting substrate of a foreign material, with refractive index compatible with light trapping schemes for the silicon. The resulting inability to nucleate growth of crystalline silicon films of good crystallographic quality on such foreign substrates, prevents the achievement of high efficiency devices using conventional single junction solar cell structures. The parallel multijunction solar cell provides a new approach for achieving high efficiencies from very poor quality material, with near unity collection probabilities for all generated carriers achieved through appropriate junction spacing. Heavy doping is used to minimise the dark saturation current contribution from the layers, therefore allowing respectable voltages. The design strategy, corresponding advantages, theoretical predictions and experimental results are presented.","PeriodicalId":20517,"journal":{"name":"Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84473832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1994-12-05DOI: 10.1109/WCPEC.1994.520129
M. Posnansky, S. Gnos, S. Coonen
An extensive utilization of photovoltaics for future electricity generation and for hybrid generation of electricity and thermal energy is possible, when PV-panels are designed to become a part of the building envelope itself. Large areas are available, since roofs and facades are perfectly suited for solar energy conversion. TALENTS ENERGY LTD has developed special PV-generators which fulfill at the same time the functions and requirements of conventional building elements. In the context of different R&D projects funded by the Swiss government to implement a series of typical building integrated photovoltaic systems, ATLANTIS ENERGY LTD was entrusted to design and build various hybrid building integrated PV-power plants. The following PV-building integrated systems are briefly discussed: the factory building 'Aerni' consisting of a 9 kW/sub el/ vertical PV-facade and of a hybrid 53 kW/sub el/ PV-system integrated into the skylights; the multifunctional PV-facade 'Scheidegger' with an installed peak power of 18 kW/sub el/; the hybrid PV-shingle roof 'Brig' with an installed peak power of 15 kW/sub el/ and 30 kW/sub th/; and the 8.4 kW/sub el/, 12 kW/sub th/ hybrid PV-shingle roof 'Rigi'.
{"title":"The importance of hybrid PV-building integration","authors":"M. Posnansky, S. Gnos, S. Coonen","doi":"10.1109/WCPEC.1994.520129","DOIUrl":"https://doi.org/10.1109/WCPEC.1994.520129","url":null,"abstract":"An extensive utilization of photovoltaics for future electricity generation and for hybrid generation of electricity and thermal energy is possible, when PV-panels are designed to become a part of the building envelope itself. Large areas are available, since roofs and facades are perfectly suited for solar energy conversion. TALENTS ENERGY LTD has developed special PV-generators which fulfill at the same time the functions and requirements of conventional building elements. In the context of different R&D projects funded by the Swiss government to implement a series of typical building integrated photovoltaic systems, ATLANTIS ENERGY LTD was entrusted to design and build various hybrid building integrated PV-power plants. The following PV-building integrated systems are briefly discussed: the factory building 'Aerni' consisting of a 9 kW/sub el/ vertical PV-facade and of a hybrid 53 kW/sub el/ PV-system integrated into the skylights; the multifunctional PV-facade 'Scheidegger' with an installed peak power of 18 kW/sub el/; the hybrid PV-shingle roof 'Brig' with an installed peak power of 15 kW/sub el/ and 30 kW/sub th/; and the 8.4 kW/sub el/, 12 kW/sub th/ hybrid PV-shingle roof 'Rigi'.","PeriodicalId":20517,"journal":{"name":"Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1994-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84567101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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