Partial shade of monolithic thin-film PV modules can cause reverse-bias conditions leading to permanent damage. In this work, we introduce a partial shade stress test for thin-film PV modules that quantifies permanent performance loss. The test reproduces shading and loading conditions that may occur in the field. It accounts for reversible light-induced performance changes and for the effects of light-enhanced reverse breakdown. We simulated the test procedure using a computer model that predicts the local voltage, current and temperature stress resulting from partial shade. We also performed the test on three commercial module types. Each module type we tested suffered permanent damage during masked ash testing totaling < 2 s of light exposure. During the subsequent stress test these module types lost 4%{11% in Pmp due to widespread formation of new shunts. One module type showed a substantial worsening of the Pmp loss upon light stabilization, underscoring the importance of this practice for proper quantification of damage.
{"title":"Partial shade stress test for thin-film photovoltaic modules","authors":"T. Silverman, M. Deceglie, C. Deline, S. Kurtz","doi":"10.1117/12.2188774","DOIUrl":"https://doi.org/10.1117/12.2188774","url":null,"abstract":"Partial shade of monolithic thin-film PV modules can cause reverse-bias conditions leading to permanent damage. In this work, we introduce a partial shade stress test for thin-film PV modules that quantifies permanent performance loss. The test reproduces shading and loading conditions that may occur in the field. It accounts for reversible light-induced performance changes and for the effects of light-enhanced reverse breakdown. We simulated the test procedure using a computer model that predicts the local voltage, current and temperature stress resulting from partial shade. We also performed the test on three commercial module types. Each module type we tested suffered permanent damage during masked ash testing totaling < 2 s of light exposure. During the subsequent stress test these module types lost 4%{11% in Pmp due to widespread formation of new shunts. One module type showed a substantial worsening of the Pmp loss upon light stabilization, underscoring the importance of this practice for proper quantification of damage.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130657809","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}
S. Martinuzzi, I. Périchaud, O. Palais, D. Barakel, Michel Gaulthier
Large multicrystalline cast silicon ingots (>310 kg) are cost effective in the photovoltaic industry and attenuate the feedstock shortage. The bulk lifetime τn and diffusion length Ln of minority carriers vary through the height due to the segregation of metallic impurities during the directional solidification. The native impurity concentrations increase from the bottom to the top of the ingot, which is solidified last, while the ingot bottom, which is solidified first, is contaminated by the contact with the crucible. It was found that τn and Ln are the smallest in the top and in the bottom of the ingot. In solar cells, the evolution is similar, however in the central part of the ingot Ln is strongly increased due to the in-diffusion of hydrogen from the SiN-H antireflection coating layer. The variations along the ingot height of the conversion efficiency η and of τn in raw wafers are well correlated, that can predict the values of η, allowing an in-line sorting of the wafers, before solar cells are made. If τn is smaller than 1 μs, as observed at the extremities of the ingot, η will be limited to 10% only; if τn is higher than 2.5 μs η achieve 15 % at least. In addition, impurity segregation phenomena around grain boundaries are observed at the extremities of the ingots, linked to the long duration of the solidification process. Reducing the height of the ingots could suppress these phenomena and not much material must be discarded. Another problem can come from the use of upgraded metallurgical silicon feedstock in which the densities of boron and phosphorus are very close. Due to the difference in the segregation coefficients, ingots may be entirely or partly p or n type, suggesting that a purification step tawards the dopants is required.
{"title":"Electrical and photovoltaic properties through a large multicrystalline Si ingot","authors":"S. Martinuzzi, I. Périchaud, O. Palais, D. Barakel, Michel Gaulthier","doi":"10.1117/12.733827","DOIUrl":"https://doi.org/10.1117/12.733827","url":null,"abstract":"Large multicrystalline cast silicon ingots (>310 kg) are cost effective in the photovoltaic industry and attenuate the feedstock shortage. The bulk lifetime τn and diffusion length Ln of minority carriers vary through the height due to the segregation of metallic impurities during the directional solidification. The native impurity concentrations increase from the bottom to the top of the ingot, which is solidified last, while the ingot bottom, which is solidified first, is contaminated by the contact with the crucible. It was found that τn and Ln are the smallest in the top and in the bottom of the ingot. In solar cells, the evolution is similar, however in the central part of the ingot Ln is strongly increased due to the in-diffusion of hydrogen from the SiN-H antireflection coating layer. The variations along the ingot height of the conversion efficiency η and of τn in raw wafers are well correlated, that can predict the values of η, allowing an in-line sorting of the wafers, before solar cells are made. If τn is smaller than 1 μs, as observed at the extremities of the ingot, η will be limited to 10% only; if τn is higher than 2.5 μs η achieve 15 % at least. In addition, impurity segregation phenomena around grain boundaries are observed at the extremities of the ingots, linked to the long duration of the solidification process. Reducing the height of the ingots could suppress these phenomena and not much material must be discarded. Another problem can come from the use of upgraded metallurgical silicon feedstock in which the densities of boron and phosphorus are very close. Due to the difference in the segregation coefficients, ingots may be entirely or partly p or n type, suggesting that a purification step tawards the dopants is required.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131860322","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}
A. Parretta, A. Antonini, M. Stefancich, V. Franceschini, G. Martinelli, M. Armani
In this paper we present a method of optical characterization of solar concentrators based on the use of a laser beam. The method, even though constrained by lengthy measurements, gives nevertheless interesting information on local mirror surface defects or manufacturing defects, like internal wall shape inaccuracies. It was applied to 3D-CPC-like concentrators and the measurements were supported by optical simulations with commercial codes. The method, simple to apply, requires just a laser to scan the CPC input aperture following a matrix-like path, at a controlled orientation of the beam. Maps of optical efficiency as function of the laser beam incidence angle are obtained by matching the CPC exit aperture with a photodetector with an efficient light trapping. The integration of each map gives the CPC efficiency resolved in angle of incidence, so curves of optical transmission (efficiency) as function of incidence angle can be drawn and the acceptance angle measured. The analysis of the single maps allows to obtain interesting information on light collection by the different regions of CPC input area. It reveals, moreover, how the efficiency of light collection depends on several factors like surface reflectivity, number of reflections of the single beam, local angle of incidence, local surface defects, and so on. By comparing the theoretical analysis with the experimental results, it is possible to emphasize the effects directly related to manufacturing defects.
{"title":"Characterization of CPC solar concentrators by a laser method","authors":"A. Parretta, A. Antonini, M. Stefancich, V. Franceschini, G. Martinelli, M. Armani","doi":"10.1117/12.733925","DOIUrl":"https://doi.org/10.1117/12.733925","url":null,"abstract":"In this paper we present a method of optical characterization of solar concentrators based on the use of a laser beam. The method, even though constrained by lengthy measurements, gives nevertheless interesting information on local mirror surface defects or manufacturing defects, like internal wall shape inaccuracies. It was applied to 3D-CPC-like concentrators and the measurements were supported by optical simulations with commercial codes. The method, simple to apply, requires just a laser to scan the CPC input aperture following a matrix-like path, at a controlled orientation of the beam. Maps of optical efficiency as function of the laser beam incidence angle are obtained by matching the CPC exit aperture with a photodetector with an efficient light trapping. The integration of each map gives the CPC efficiency resolved in angle of incidence, so curves of optical transmission (efficiency) as function of incidence angle can be drawn and the acceptance angle measured. The analysis of the single maps allows to obtain interesting information on light collection by the different regions of CPC input area. It reveals, moreover, how the efficiency of light collection depends on several factors like surface reflectivity, number of reflections of the single beam, local angle of incidence, local surface defects, and so on. By comparing the theoretical analysis with the experimental results, it is possible to emphasize the effects directly related to manufacturing defects.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124496781","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}
Omer Korech, J. Gordon, E. Katz, D. Feuermann, N. Eisenberg
Essentially loss-less all-dielectric micro-fabricated optics can be tailored to completely eliminate the shadowing losses metallization grids create on the surface of concentrator solar cells. The nonimaging micro-concentrator exploits total internal reflection to redistribute the elevated flux from available macro-concentrators, rather than increasing overall concentration. The optical designs permit widening the metal fingers toward lessening series resistance losses, which can also finesse the need for the intricate metallization patterns of some high-flux cells. Realistic net efficiency gains of ~15% (relative) are achievable in a wide variety of concentrator cells.
{"title":"Efficiency enhancement in concentrator solar cells by dielectric micro-concentrators","authors":"Omer Korech, J. Gordon, E. Katz, D. Feuermann, N. Eisenberg","doi":"10.1117/12.733024","DOIUrl":"https://doi.org/10.1117/12.733024","url":null,"abstract":"Essentially loss-less all-dielectric micro-fabricated optics can be tailored to completely eliminate the shadowing losses metallization grids create on the surface of concentrator solar cells. The nonimaging micro-concentrator exploits total internal reflection to redistribute the elevated flux from available macro-concentrators, rather than increasing overall concentration. The optical designs permit widening the metal fingers toward lessening series resistance losses, which can also finesse the need for the intricate metallization patterns of some high-flux cells. Realistic net efficiency gains of ~15% (relative) are achievable in a wide variety of concentrator cells.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115384356","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}
W. McMahon, K. Emery, D. Friedman, L. Ottoson, M. Young, J. Ward, C. Kramer, A. Duda, S. Kurtz
Optimizing a concentrator system which uses multijunction solar cells is challenging because: (a) the conditions are variable, so the solar cells rarely operate under optimal conditions and (b) the conditions are not controlled, so any design problems are difficult to characterize. Any change in the spectral content of direct-beam sunlight as it passes through the concentrator optics is of particular interest, as it can reduce the performance of multijunction cells and is difficult to characterize. Here we show how the fill factor can be used to detect and diagnose this sort of a "spectral skewing" by the concentrator optics during outdoor operation. The work presented here is for GaInP2/GaAs tandem cells, but the conclusions are equally valid for GaInP2/GaAs/Ge triple-junction cells.
{"title":"Daily fill factor variation as a diagnostic probe of multijunction concentrator systems during outdoor operation","authors":"W. McMahon, K. Emery, D. Friedman, L. Ottoson, M. Young, J. Ward, C. Kramer, A. Duda, S. Kurtz","doi":"10.1117/12.732604","DOIUrl":"https://doi.org/10.1117/12.732604","url":null,"abstract":"Optimizing a concentrator system which uses multijunction solar cells is challenging because: (a) the conditions are variable, so the solar cells rarely operate under optimal conditions and (b) the conditions are not controlled, so any design problems are difficult to characterize. Any change in the spectral content of direct-beam sunlight as it passes through the concentrator optics is of particular interest, as it can reduce the performance of multijunction cells and is difficult to characterize. Here we show how the fill factor can be used to detect and diagnose this sort of a \"spectral skewing\" by the concentrator optics during outdoor operation. The work presented here is for GaInP2/GaAs tandem cells, but the conclusions are equally valid for GaInP2/GaAs/Ge triple-junction cells.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125061760","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}
B. Marsen, B. Cole, S. Dorn, R. Rocheleau, E. Miller
Copper chalcopyrite films exhibit properties suitable for solar energy conversion processes such as direct bandgap, and excellent carrier transport. To explore the possibilities of solar-powered hydrogen production by photoelectrolysis using these materials, we have synthesized p-type polycrystalline CuGaSe2 films by vacuum co-evaporation of the elemental constituents, and performed physical and electrochemical characterizations of the resulting films and electrodes. Based on CuGaSe2 material with 1.65 eV bandgap, a 2.2 micron thick electrode exhibited an outdoor 1-sun photocurrent of 16 mA/cm2, while a 0.9 micron thin device still produced 12.6 mA/cm2 in conjunction with vigorous gas evolution. Flatband potential measurements and bias voltage requirements for saturation photocurrents indicate a valence band position to high for practical device implementation. Future photoelectrolysis devices may be based on copper chalcopyrites with lower valence band maximum in conjunction with a suitable auxiliary junction.
{"title":"Copper gallium diselenide photocathodes for solar photoelectrolysis","authors":"B. Marsen, B. Cole, S. Dorn, R. Rocheleau, E. Miller","doi":"10.1117/12.732737","DOIUrl":"https://doi.org/10.1117/12.732737","url":null,"abstract":"Copper chalcopyrite films exhibit properties suitable for solar energy conversion processes such as direct bandgap, and excellent carrier transport. To explore the possibilities of solar-powered hydrogen production by photoelectrolysis using these materials, we have synthesized p-type polycrystalline CuGaSe2 films by vacuum co-evaporation of the elemental constituents, and performed physical and electrochemical characterizations of the resulting films and electrodes. Based on CuGaSe2 material with 1.65 eV bandgap, a 2.2 micron thick electrode exhibited an outdoor 1-sun photocurrent of 16 mA/cm2, while a 0.9 micron thin device still produced 12.6 mA/cm2 in conjunction with vigorous gas evolution. Flatband potential measurements and bias voltage requirements for saturation photocurrents indicate a valence band position to high for practical device implementation. Future photoelectrolysis devices may be based on copper chalcopyrites with lower valence band maximum in conjunction with a suitable auxiliary junction.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128501332","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}
Bandgap, band edge positions as well as the overall band structure of semiconductors are of crucial importance in photoelectrochemical and photocatalytic applications. The energy position of the band edge level can be controlled by the electronegativity of the dopants, the pH of the solution (flatband potential variation of 60 mV per pH unit), as well as by quantum confinement effects. Accordingly, band edges and bandgap can be tailored to achieve specific electronic, optical or photocatalytic properties. Synchrotron radiation with photon energy at or below 1 keV is giving new insight into such areas as condensed matter physics and extreme ultraviolet optics technology. In the soft x-ray region, the question tends to be, what are the electrons doing as they migrated between the atoms. In this paper, I will present a number of soft x-ray spectroscopic study of nanostructured 3d metal compounds Fe2O3 and ZnO.
{"title":"Electronic structure characterization and bandgap engineering of solar hydrogen materials","authors":"Jinghua Guo","doi":"10.1117/12.734618","DOIUrl":"https://doi.org/10.1117/12.734618","url":null,"abstract":"Bandgap, band edge positions as well as the overall band structure of semiconductors are of crucial importance in photoelectrochemical and photocatalytic applications. The energy position of the band edge level can be controlled by the electronegativity of the dopants, the pH of the solution (flatband potential variation of 60 mV per pH unit), as well as by quantum confinement effects. Accordingly, band edges and bandgap can be tailored to achieve specific electronic, optical or photocatalytic properties. Synchrotron radiation with photon energy at or below 1 keV is giving new insight into such areas as condensed matter physics and extreme ultraviolet optics technology. In the soft x-ray region, the question tends to be, what are the electrons doing as they migrated between the atoms. In this paper, I will present a number of soft x-ray spectroscopic study of nanostructured 3d metal compounds Fe2O3 and ZnO.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128108872","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}
The IR loss in diffuse measurements made by thermopile pyranometers is examined. Diffuse measurements are used for the study of IR losses because diffuse irradiance is much smaller than the total irradiance and hence the IR effects can be more clearly seen. Specifically, diffuse measurements of an Eppley PSP pyranometer are compared to those made with a Schenk Star pyranometer. Pyranometers with black and white or star type junctions suffer minimal IR loss because the reference and receiving junctions of the thermopile are at the same thermal level. The difference between diffuse values can be attributed to calibration and cosine response errors as well as IR loss. This is a preliminary study over one month when pyrgeometer data are available. Examination of the differences at various times of the year and at more than one location is necessary to generalize the findings in this report. Several methods of correcting for IR loss are examined. First subtracting out the average nighttime offset during the day is tested. Next an extrapolation between early morning and late evening offsets is tested. This should help eliminate the IR offset in both the morning and evening hours, but underestimate the IR losses during the rest of the day. Next, correlations of IR losses calculated using pyrgeometer measurements with temperature, relative humidity, and irradiance are evaluated. Initial results show that it should be possible to use more commonly available measurements rather than prygeometer data to estimate IR loss for Eppley PSP pyranometers.
{"title":"Evaluation of methods to correct for IR loss in Eppley PSP diffuse measurements","authors":"F. Vignola, Ch. D. Long, I. Reda","doi":"10.1117/12.734474","DOIUrl":"https://doi.org/10.1117/12.734474","url":null,"abstract":"The IR loss in diffuse measurements made by thermopile pyranometers is examined. Diffuse measurements are used for the study of IR losses because diffuse irradiance is much smaller than the total irradiance and hence the IR effects can be more clearly seen. Specifically, diffuse measurements of an Eppley PSP pyranometer are compared to those made with a Schenk Star pyranometer. Pyranometers with black and white or star type junctions suffer minimal IR loss because the reference and receiving junctions of the thermopile are at the same thermal level. The difference between diffuse values can be attributed to calibration and cosine response errors as well as IR loss. This is a preliminary study over one month when pyrgeometer data are available. Examination of the differences at various times of the year and at more than one location is necessary to generalize the findings in this report. Several methods of correcting for IR loss are examined. First subtracting out the average nighttime offset during the day is tested. Next an extrapolation between early morning and late evening offsets is tested. This should help eliminate the IR offset in both the morning and evening hours, but underestimate the IR losses during the rest of the day. Next, correlations of IR losses calculated using pyrgeometer measurements with temperature, relative humidity, and irradiance are evaluated. Initial results show that it should be possible to use more commonly available measurements rather than prygeometer data to estimate IR loss for Eppley PSP pyranometers.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134027279","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}
The properties of a transparent conductive oxide (TCO) used as a front electrode for thin-film solar cells and modules play a major role in determining the maximum attainable conversion efficiency. Doped ZnO is an important TCO that is widely used in amorphous/nanocrystalline silicon (a-Si/nc-Si) and CIGS thin-film solar cells. In the case of a-Si/nc-Si cells, the ZnO thin film should be textured to promote light trapping to increase the short-circuit current density Jsc. In this work, textured, aluminum-doped ZnO (ZnO:Al) thin films have been directly deposited by a sputtering-based method and without the need for post-deposition etching. The morphology, optical properties and electrical properties of the films have been studied. SEM micrographs show that feature sizes around 0.2 - 0.4μm have been achieved at a film thickness of 1μm, and that the morphology can be controlled by the deposition conditions. AFM images were analyzed to extract a set of topographic parameters (amplitude, spatial, and hybrid). The optical transmission, haze, and angle-resolved light scattering of the textured ZnO:Al films were measured and compared to properties of commercially-available textured SnO2:F thin films on glass. Higher haze and reduced absorption could be obtained with the textured ZnO:Al films. Hall effect measurements on these films yielded a carrier concentration and mobility of 2.75 x 1020cm-3 and 24.1cm2/Vs, respectively. We also report that the use of these textured ZnO:Al films as the top TCO for CIGS solar cells results in reduced cell reflectance and increased Jsc. The novel deposition method provides a potential pathway to large area and cost effective production of a textured ZnO TCO for thin-film PV manufacturing operations.
透明导电氧化物(TCO)用作薄膜太阳能电池和组件的前电极，其性能在决定可达到的最大转换效率方面起着重要作用。ZnO是一种重要的TCO，广泛应用于非晶/纳米晶硅(a-Si/nc-Si)和CIGS薄膜太阳能电池中。在a-Si/nc-Si电池中，需要对ZnO薄膜进行织构以促进光捕获，从而提高短路电流密度Jsc。在这项工作中，通过基于溅射的方法直接沉积了有织构的铝掺杂ZnO (ZnO:Al)薄膜，而无需沉积后蚀刻。研究了薄膜的形貌、光学性能和电学性能。SEM显微图显示，在薄膜厚度为1μm时，可以获得0.2 ~ 0.4μm左右的特征尺寸，且形貌可以由沉积条件控制。分析AFM图像以提取一组地形参数(振幅，空间和混合)。测量了ZnO:Al织构薄膜的光学透射率、雾度和角分辨光散射，并与市售的SnO2:F玻璃薄膜的性能进行了比较。织构后的ZnO:Al薄膜具有较高的雾度和较低的吸收率。对这些薄膜进行霍尔效应测量，载流子浓度和迁移率分别为2.75 x 1020cm-3和24.1cm /Vs。我们还报道，使用这些织构ZnO:Al薄膜作为CIGS太阳能电池的顶部TCO，可以降低电池反射率并增加Jsc。这种新的沉积方法为薄膜光伏制造操作提供了大面积和经济有效地生产纹理ZnO TCO的潜在途径。
{"title":"Textured, doped, ZnO thin films produced by a new process for a-Si and CIGS solar cell application","authors":"S. Guo, L. Sahoo, G. Sosale, A. Delahoy","doi":"10.1117/12.736084","DOIUrl":"https://doi.org/10.1117/12.736084","url":null,"abstract":"The properties of a transparent conductive oxide (TCO) used as a front electrode for thin-film solar cells and modules play a major role in determining the maximum attainable conversion efficiency. Doped ZnO is an important TCO that is widely used in amorphous/nanocrystalline silicon (a-Si/nc-Si) and CIGS thin-film solar cells. In the case of a-Si/nc-Si cells, the ZnO thin film should be textured to promote light trapping to increase the short-circuit current density Jsc. In this work, textured, aluminum-doped ZnO (ZnO:Al) thin films have been directly deposited by a sputtering-based method and without the need for post-deposition etching. The morphology, optical properties and electrical properties of the films have been studied. SEM micrographs show that feature sizes around 0.2 - 0.4μm have been achieved at a film thickness of 1μm, and that the morphology can be controlled by the deposition conditions. AFM images were analyzed to extract a set of topographic parameters (amplitude, spatial, and hybrid). The optical transmission, haze, and angle-resolved light scattering of the textured ZnO:Al films were measured and compared to properties of commercially-available textured SnO2:F thin films on glass. Higher haze and reduced absorption could be obtained with the textured ZnO:Al films. Hall effect measurements on these films yielded a carrier concentration and mobility of 2.75 x 1020cm-3 and 24.1cm2/Vs, respectively. We also report that the use of these textured ZnO:Al films as the top TCO for CIGS solar cells results in reduced cell reflectance and increased Jsc. The novel deposition method provides a potential pathway to large area and cost effective production of a textured ZnO TCO for thin-film PV manufacturing operations.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123995769","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}
The measurement of the horizontal diffuse radiation, a priori a straightforward task, is fraught with difficulties. It is possible to measure the diffuse radiation by both direct and indirect methods. The most accurate method is probably the indirect one, which utilizes concurrent measurements of the horizontal global and the normal incidence beam radiation. The disadvantage of this method is the relatively expensive tracking system required for measuring the latter. The diffuse radiation can be measured directly with a pyranometer outfitted with either an occulting disk or shadow ring, which prevent the beam radiation from impinging on the pyranometer sensor. The former method can provide accurate measurements of the diffuse radiation but requires a relatively expensive sun tracking system in the east-west axis. The shadow ring is a stationary device with regard to the east-west axis and blocks the beam radiation component by creating a permanent shadow on the pyranometer sensor. The disadvantage of the shadow ring is that it also blocks a portion of the sky, which necessitates a geometrical correction factor. There is also a need to correct for anisotropic sky conditions. Four correction models have been applied to the data and the results evaluated and ranked.
{"title":"The evaluation of four different diffuse radiation correction models applied to shadow ring measurements for Beer Sheva, Israel","authors":"A. Kudish, Efim G. Evseev","doi":"10.1117/12.731555","DOIUrl":"https://doi.org/10.1117/12.731555","url":null,"abstract":"The measurement of the horizontal diffuse radiation, a priori a straightforward task, is fraught with difficulties. It is possible to measure the diffuse radiation by both direct and indirect methods. The most accurate method is probably the indirect one, which utilizes concurrent measurements of the horizontal global and the normal incidence beam radiation. The disadvantage of this method is the relatively expensive tracking system required for measuring the latter. The diffuse radiation can be measured directly with a pyranometer outfitted with either an occulting disk or shadow ring, which prevent the beam radiation from impinging on the pyranometer sensor. The former method can provide accurate measurements of the diffuse radiation but requires a relatively expensive sun tracking system in the east-west axis. The shadow ring is a stationary device with regard to the east-west axis and blocks the beam radiation component by creating a permanent shadow on the pyranometer sensor. The disadvantage of the shadow ring is that it also blocks a portion of the sky, which necessitates a geometrical correction factor. There is also a need to correct for anisotropic sky conditions. Four correction models have been applied to the data and the results evaluated and ranked.","PeriodicalId":142821,"journal":{"name":"SPIE Optics + Photonics for Sustainable Energy","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130554653","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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