Pub Date : 1996-05-13DOI: 10.1109/PVSC.1996.564219
D.D. Smith, D. Aiken, A. M. Barnett
Thin silicon solar cells must meet several requirements for high efficiency. These are minority carrier diffusion lengths exceeding the active layer thickness, enhanced absorption from light trapping, and passivation of all surfaces bounding the active region. A thin silicon solar cell will in general be supported by a foreign substrate. This approach will produce a buried interface which will not allow for characterization of surface recombination by short wavelength spectral response. New methods must be developed to measure and control surface recombination at a buried interface. A gated diode device structure is proposed for this purpose. The gate will be formed at the buried interface. Varying the gate bias is expected to control carrier populations due to field effect, and hence the recombination rate at the back surface. In this work, a thin layer of single crystal silicon is formed on the gate structure by epitaxial lateral overgrowth (ELO) using liquid phase epitaxy. The dielectric insulator is currently thermally grown SiO/sub 2/. This device structure could enable control of buried surface recombination for a wide variety of substrate materials.
{"title":"Surface recombination at the Si/SiO/sub 2/ overgrowth interface","authors":"D.D. Smith, D. Aiken, A. M. Barnett","doi":"10.1109/PVSC.1996.564219","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564219","url":null,"abstract":"Thin silicon solar cells must meet several requirements for high efficiency. These are minority carrier diffusion lengths exceeding the active layer thickness, enhanced absorption from light trapping, and passivation of all surfaces bounding the active region. A thin silicon solar cell will in general be supported by a foreign substrate. This approach will produce a buried interface which will not allow for characterization of surface recombination by short wavelength spectral response. New methods must be developed to measure and control surface recombination at a buried interface. A gated diode device structure is proposed for this purpose. The gate will be formed at the buried interface. Varying the gate bias is expected to control carrier populations due to field effect, and hence the recombination rate at the back surface. In this work, a thin layer of single crystal silicon is formed on the gate structure by epitaxial lateral overgrowth (ELO) using liquid phase epitaxy. The dielectric insulator is currently thermally grown SiO/sub 2/. This device structure could enable control of buried surface recombination for a wide variety of substrate materials.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124062405","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564294
N. Orbey, H. Hichri, R. Birkmire, T. Russell
A chemical reaction analysis of the selenization of copper indium layers to form copper indium diselenide is presented. Time progressive selenizations were carried out in a tubular laminar flow reactor in a dilute H/sub 2/Se atmosphere at 250, 325 and 400/spl deg/C. The reacted films were analyzed by X-ray diffraction and atomic absorption spectroscopy. The chemical species present in the reacted films were identified and a reaction network for film formation is proposed. The data from time progressive selenizations were analyzed to obtain species concentration profiles. Rate expressions were postulated and a mathematical model for the selenization was developed. The behavior of the model is compared with the experimentally determined species concentrations to obtain specific reaction rate constants at each temperature and the activation energies. This information is needed for the design and process control of commercial scale selenization reactors.
{"title":"Reaction analysis of the formation of CIS at temperatures from 250 to 400/spl deg/C","authors":"N. Orbey, H. Hichri, R. Birkmire, T. Russell","doi":"10.1109/PVSC.1996.564294","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564294","url":null,"abstract":"A chemical reaction analysis of the selenization of copper indium layers to form copper indium diselenide is presented. Time progressive selenizations were carried out in a tubular laminar flow reactor in a dilute H/sub 2/Se atmosphere at 250, 325 and 400/spl deg/C. The reacted films were analyzed by X-ray diffraction and atomic absorption spectroscopy. The chemical species present in the reacted films were identified and a reaction network for film formation is proposed. The data from time progressive selenizations were analyzed to obtain species concentration profiles. Rate expressions were postulated and a mathematical model for the selenization was developed. The behavior of the model is compared with the experimentally determined species concentrations to obtain specific reaction rate constants at each temperature and the activation energies. This information is needed for the design and process control of commercial scale selenization reactors.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126245662","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564400
C. Eberspacher, V. Fthenakis, P. Moskowitz
One of the most promising materials for low-cost thin film photovoltaic cells is copper indium selenide (CuInSe/sub 2/ or CIS). As with any new material, successful commercialization of CIS photovoltaic (PV) technology will require attention to environmental issues related to the sources of raw materials, their usage, and the disposal and/or recycling of products at the end of their useful life. This paper focuses on three specific environmental issues related to CIS technology: (i) economics of the use and re-use of materials; (ii) regulations on environmental disposal and waste handling; and (iii) logistics and economics of recycling and disposal of products by industries faced with comparable environmental issues.
{"title":"Environmental issues related to commercialization of CuInSe/sub 2/-based photovoltaics","authors":"C. Eberspacher, V. Fthenakis, P. Moskowitz","doi":"10.1109/PVSC.1996.564400","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564400","url":null,"abstract":"One of the most promising materials for low-cost thin film photovoltaic cells is copper indium selenide (CuInSe/sub 2/ or CIS). As with any new material, successful commercialization of CIS photovoltaic (PV) technology will require attention to environmental issues related to the sources of raw materials, their usage, and the disposal and/or recycling of products at the end of their useful life. This paper focuses on three specific environmental issues related to CIS technology: (i) economics of the use and re-use of materials; (ii) regulations on environmental disposal and waste handling; and (iii) logistics and economics of recycling and disposal of products by industries faced with comparable environmental issues.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121933188","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 : 1996-05-13DOI: 10.1109/PVSC.1996.563970
S. Wojtczuk, P. Colter, N. Karam, H. Serreze, G. Summers, R. Walters
Indium phosphide (InP) space solar cells were made by Spire on lightweight Si wafers to greatly increase the cell end-of-life (EOL) power density. A NASA-measured best cell efficiency of 12.5% was obtained at one-sun AM0 beginning-of-life (BOL) for a 2/spl times/4 cm cell. Average efficiency for fifteen 2/spl times/2 cm InP heteroepitaxial cells on 16 mil Si wafers tested by NASA was 12.3%. Data are presented comparing 1 MeV electron and 3.9 MeV alpha particle irradiation showing relatively little cell power output degradation out to a very high fluence (less than 20% after a fluence of about 4/spl times/10/sup 16/ 1 MeV electrons/cm/sup 2/, about 40/spl times/ the "standard" fluence). Calculations are presented which show that in very high radiation environments (e.g. van Allen proton belts), these cells can provide over twice as much EOL power density than GaAs/Ge or Si cells.
{"title":"Radiation-hard, lightweight 12% AM0 BOL InP/Si solar cells","authors":"S. Wojtczuk, P. Colter, N. Karam, H. Serreze, G. Summers, R. Walters","doi":"10.1109/PVSC.1996.563970","DOIUrl":"https://doi.org/10.1109/PVSC.1996.563970","url":null,"abstract":"Indium phosphide (InP) space solar cells were made by Spire on lightweight Si wafers to greatly increase the cell end-of-life (EOL) power density. A NASA-measured best cell efficiency of 12.5% was obtained at one-sun AM0 beginning-of-life (BOL) for a 2/spl times/4 cm cell. Average efficiency for fifteen 2/spl times/2 cm InP heteroepitaxial cells on 16 mil Si wafers tested by NASA was 12.3%. Data are presented comparing 1 MeV electron and 3.9 MeV alpha particle irradiation showing relatively little cell power output degradation out to a very high fluence (less than 20% after a fluence of about 4/spl times/10/sup 16/ 1 MeV electrons/cm/sup 2/, about 40/spl times/ the \"standard\" fluence). Calculations are presented which show that in very high radiation environments (e.g. van Allen proton belts), these cells can provide over twice as much EOL power density than GaAs/Ge or Si cells.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"130 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115885044","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564259
A. Delahoy, A. Payne
A new method is described to determine the internal series resistance of thin film solar cells. The method involves illumination of a small area of the solar cell with light sufficiently intense to make the internal resistance easily observable. For the CIS and CIGS cells examined, specific internal resistances ranging between 7/spl times/10/sup -2/ and 3/spl times/10/sup -4/ /spl Omega/ cm/sup 2/ were obtained. Such remarkably low values confirm the ability of CIGS to function as a concentrator solar cell.
{"title":"Determination of the internal series resistance of CIS and CIGS photovoltaic cell structures","authors":"A. Delahoy, A. Payne","doi":"10.1109/PVSC.1996.564259","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564259","url":null,"abstract":"A new method is described to determine the internal series resistance of thin film solar cells. The method involves illumination of a small area of the solar cell with light sufficiently intense to make the internal resistance easily observable. For the CIS and CIGS cells examined, specific internal resistances ranging between 7/spl times/10/sup -2/ and 3/spl times/10/sup -4/ /spl Omega/ cm/sup 2/ were obtained. Such remarkably low values confirm the ability of CIGS to function as a concentrator solar cell.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132115357","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564275
J. Gray
The objective of this paper is to present a numerical simulation tool that can be used as an aid in the interpretation of the C-V characteristics of thin-film solar cells. The example simulations presented here are for a ZnO/CdS/CuInSe/sub 2/ solar cell, but the simulation tool can be used for a variety of solar cells, including CdTe. Model equations for the simulation of the small-signal behavior of semiconductor devices are presented. Sample simulations incorporating these small-signal equations into a detailed numerical model are interpreted.
{"title":"Interpretation of capacitance-voltage characteristics in thin-film solar cells using a detailed numerical model","authors":"J. Gray","doi":"10.1109/PVSC.1996.564275","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564275","url":null,"abstract":"The objective of this paper is to present a numerical simulation tool that can be used as an aid in the interpretation of the C-V characteristics of thin-film solar cells. The example simulations presented here are for a ZnO/CdS/CuInSe/sub 2/ solar cell, but the simulation tool can be used for a variety of solar cells, including CdTe. Model equations for the simulation of the small-signal behavior of semiconductor devices are presented. Sample simulations incorporating these small-signal equations into a detailed numerical model are interpreted.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134029369","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564030
J. Gee, R. King, K. Mitchell
We performed a detailed study to examine the limiting performance available using "photovoltaic-grade" Cz silicon. Photovoltaic-grade silicon refers to silicon produced by the photovoltaic industry, which may differ from the silicon used in the semiconductor device industry in impurity and defect concentrations. The study included optimization of fabrication processes, development of advanced device structures, and detailed model calculations to project future performance improvements. Process and device optimization resulted in demonstration of 75-/spl mu/s bulk lifetimes and 17.6% efficient large-area cells using photovoltaic-grade Cz silicon. Detailed calculations based on the material and device evaluation of the present work project efficiencies of 20% for photovoltaic-grade Cz silicon with properly optimized processing and device structures.
{"title":"High-efficiency cell structures and processes applied to photovoltaic-grade Czochralski silicon","authors":"J. Gee, R. King, K. Mitchell","doi":"10.1109/PVSC.1996.564030","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564030","url":null,"abstract":"We performed a detailed study to examine the limiting performance available using \"photovoltaic-grade\" Cz silicon. Photovoltaic-grade silicon refers to silicon produced by the photovoltaic industry, which may differ from the silicon used in the semiconductor device industry in impurity and defect concentrations. The study included optimization of fabrication processes, development of advanced device structures, and detailed model calculations to project future performance improvements. Process and device optimization resulted in demonstration of 75-/spl mu/s bulk lifetimes and 17.6% efficient large-area cells using photovoltaic-grade Cz silicon. Detailed calculations based on the material and device evaluation of the present work project efficiencies of 20% for photovoltaic-grade Cz silicon with properly optimized processing and device structures.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"188 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133997463","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564003
E. Gaddy
Spacecraft solar array engineers now have cell choices running from inexpensive and less efficient silicon (Si) cells, to gallium arsenide on germanium (GaAs/Ge) cells, to more expensive and efficient multi-junction (MJ) cells. This paper finds that the more array weight can be reduced by using more efficient cells, even when they are a very expensive option in terms of the array alone, and put into the spacecraft payload i.e. the scientific instruments or in the case of commercial spacecraft, the communications equipment, the more cost effective the spacecraft array system. This is true for a wide variety of spacecraft. This is because of the very high price of launching a spacecraft payload and supporting it with a spacecraft.
{"title":"Cost performance of multi-junction, gallium arsenide, and silicon solar cells on spacecraft","authors":"E. Gaddy","doi":"10.1109/PVSC.1996.564003","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564003","url":null,"abstract":"Spacecraft solar array engineers now have cell choices running from inexpensive and less efficient silicon (Si) cells, to gallium arsenide on germanium (GaAs/Ge) cells, to more expensive and efficient multi-junction (MJ) cells. This paper finds that the more array weight can be reduced by using more efficient cells, even when they are a very expensive option in terms of the array alone, and put into the spacecraft payload i.e. the scientific instruments or in the case of commercial spacecraft, the communications equipment, the more cost effective the spacecraft array system. This is true for a wide variety of spacecraft. This is because of the very high price of launching a spacecraft payload and supporting it with a spacecraft.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131526176","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564429
E. Van Dyk, T. Strand, R. Hansen
This paper presents an analysis of performance data on the two 6-kW/sub AC/ grid-connected photovoltaic systems at the National Renewable Energy Laboratory (NREL). The performance parameters analyzed include DC and AC power, aperture efficiency, energy, capacity factor and performance index which are compared to plane-of-array irradiance, ambient temperature, and back-of-module temperature as a function of time, either daily or monthly. Power ratings of the systems were also obtained for data corresponding to different test conditions. This study has shown, in addition to expected seasonal trends, that system monitoring is a valuable tool in assessing performance and detecting faulty equipment. In addition, methods applied for this study may be used to evaluate and compare systems employing different cell technologies.
{"title":"Technical evaluation of two 6-kW mono-Si photovoltaic systems at the National Renewable Energy Laboratory","authors":"E. Van Dyk, T. Strand, R. Hansen","doi":"10.1109/PVSC.1996.564429","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564429","url":null,"abstract":"This paper presents an analysis of performance data on the two 6-kW/sub AC/ grid-connected photovoltaic systems at the National Renewable Energy Laboratory (NREL). The performance parameters analyzed include DC and AC power, aperture efficiency, energy, capacity factor and performance index which are compared to plane-of-array irradiance, ambient temperature, and back-of-module temperature as a function of time, either daily or monthly. Power ratings of the systems were also obtained for data corresponding to different test conditions. This study has shown, in addition to expected seasonal trends, that system monitoring is a valuable tool in assessing performance and detecting faulty equipment. In addition, methods applied for this study may be used to evaluate and compare systems employing different cell technologies.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132808939","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 : 1996-05-13DOI: 10.1109/PVSC.1996.564017
M. O'neill
Since 1986, ENTECH has been developing lightweight, high-performance Fresnel lens optics for space photovoltaic concentrator systems. This development work has been technically and financially supported by NASA-Lewis, SDIO, BMDO, Boeing, JX Crystals and AEC-ABLE. A fully functional experimental mini-dome Fresnel lens concentrator solar cell array was onboard the PASP Plus mission launched in August 1994. This array, assembled by Boeing using mechanically stacked multijunction (MSMJ) solar cells, confirmed the high-performance and low-radiation-degradation characteristics predicted for the refractive concentrator approach. Since PASP Plus, ENTECH has developed a line-focus Fresnel lens offering much improved manufacturability, cost, and sun-pointing error tolerance. This paper presents the latest line-focus optical designs customized for use with MSMJ cells and with monolithic multijunction (MMJ) cells.
{"title":"Line-focus optics for multijunction cells in space power arrays","authors":"M. O'neill","doi":"10.1109/PVSC.1996.564017","DOIUrl":"https://doi.org/10.1109/PVSC.1996.564017","url":null,"abstract":"Since 1986, ENTECH has been developing lightweight, high-performance Fresnel lens optics for space photovoltaic concentrator systems. This development work has been technically and financially supported by NASA-Lewis, SDIO, BMDO, Boeing, JX Crystals and AEC-ABLE. A fully functional experimental mini-dome Fresnel lens concentrator solar cell array was onboard the PASP Plus mission launched in August 1994. This array, assembled by Boeing using mechanically stacked multijunction (MSMJ) solar cells, confirmed the high-performance and low-radiation-degradation characteristics predicted for the refractive concentrator approach. Since PASP Plus, ENTECH has developed a line-focus Fresnel lens offering much improved manufacturability, cost, and sun-pointing error tolerance. This paper presents the latest line-focus optical designs customized for use with MSMJ cells and with monolithic multijunction (MMJ) cells.","PeriodicalId":410394,"journal":{"name":"Conference Record of the Twenty Fifth IEEE Photovoltaic Specialists Conference - 1996","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126550003","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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