Pub Date : 2011-06-19DOI: 10.1109/PVSC.2011.6186263
T. Ohshima, Shin‐ichiro Sato, M. Imaizumi, T. Sugaya, S. Niki
GaAs PiN solar cells with 50 In0.4Ga0.6As quantum dot (QD) layers were irradiated with 1 MeV electrons up to 1×1016 /cm2. The change in their electrical characteristics under an air mass zero (AM 0) was studied using an in-situ measurement system. The open circuit voltage (VOC) for InGaAs 50 QD solar cells remains 90 % of its initial value after electron irradiation at a fluence of 1×10 16/cm2. On the other hand, the short current circuit (ISC) and maximum power (PMAX) for 50 QD solar cells decrease to approximately 80 and 60 % of their initial value after the same irradiation, respectively. The recovery of the electrical characteristics of both InGaAs 50QD solar cells as well as GaAs PiN solar cells without the QD layers degraded by electron irradiation are observed under AM0 light illumination at room temperature after irradiation.
{"title":"Radiation response of the electrical characteristics of GaAs solar cells with quantum dot layers","authors":"T. Ohshima, Shin‐ichiro Sato, M. Imaizumi, T. Sugaya, S. Niki","doi":"10.1109/PVSC.2011.6186263","DOIUrl":"https://doi.org/10.1109/PVSC.2011.6186263","url":null,"abstract":"GaAs PiN solar cells with 50 In<inf>0.4</inf>Ga<inf>0.6</inf>As quantum dot (QD) layers were irradiated with 1 MeV electrons up to 1×10<sup>16</sup> /cm<sup>2</sup>. The change in their electrical characteristics under an air mass zero (AM 0) was studied using an in-situ measurement system. The open circuit voltage (V<inf>OC</inf>) for InGaAs 50 QD solar cells remains 90 % of its initial value after electron irradiation at a fluence of 1×10 <sup>16</sup>/cm<sup>2</sup>. On the other hand, the short current circuit (I<inf>SC</inf>) and maximum power (P<inf>MAX</inf>) for 50 QD solar cells decrease to approximately 80 and 60 % of their initial value after the same irradiation, respectively. The recovery of the electrical characteristics of both InGaAs 50QD solar cells as well as GaAs PiN solar cells without the QD layers degraded by electron irradiation are observed under AM0 light illumination at room temperature after irradiation.","PeriodicalId":373149,"journal":{"name":"2011 37th IEEE Photovoltaic Specialists Conference","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128537441","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 : 2011-06-19DOI: 10.1109/PVSC.2011.6185891
Wooseok Ki, H. Hillhouse
Earth abundant absorber materials are the most promising candidates for terawatt-scale thin film photovoltaics due to the robust supply chains for the elements involved. The strongest initial candidate appears to be Cu2ZnSnS4 (CZTS), but there are other potential material systems such as FeS2, CuO, and PbS that are just beginning to be re-examined with solution phase processing. Here we report a new, facile, and scalable chemical route to Earth abundant element thin film solar cells by coating a solution of highly soluble, inexpensive, and commercially available precursors in an environmentally friendly non-toxic solvent to form device quality films. Air-stable CZTS photovoltaic devices with 4.1% total area power conversion efficiency are obtained. We have generalized the chemical route and have used it to also fabricate PbS devices that are 1.5% efficient.
{"title":"A general route to Earth abundant element absorber layers for thin film photovoltaics with high yield using molecular precursors and non-toxic solvents","authors":"Wooseok Ki, H. Hillhouse","doi":"10.1109/PVSC.2011.6185891","DOIUrl":"https://doi.org/10.1109/PVSC.2011.6185891","url":null,"abstract":"Earth abundant absorber materials are the most promising candidates for terawatt-scale thin film photovoltaics due to the robust supply chains for the elements involved. The strongest initial candidate appears to be Cu2ZnSnS4 (CZTS), but there are other potential material systems such as FeS2, CuO, and PbS that are just beginning to be re-examined with solution phase processing. Here we report a new, facile, and scalable chemical route to Earth abundant element thin film solar cells by coating a solution of highly soluble, inexpensive, and commercially available precursors in an environmentally friendly non-toxic solvent to form device quality films. Air-stable CZTS photovoltaic devices with 4.1% total area power conversion efficiency are obtained. We have generalized the chemical route and have used it to also fabricate PbS devices that are 1.5% efficient.","PeriodicalId":373149,"journal":{"name":"2011 37th IEEE Photovoltaic Specialists Conference","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128536351","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 : 2011-06-19DOI: 10.1109/PVSC.2011.6185950
Z. Beiley, Craig H. Peters, I. T. Sachs-Quitana, E. Hoke, G. F. Burkhard, M. McGehee
Bulk heterojunction solar cells (BHJs) based on poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) can have internal quantum efficiencies approaching 100% but require active layers that are too thin to absorb more than ∼70% of the above bandgap light.[1] In this work, we demonstrate that PCDTBT films contain a high density of hole-traps, which correlate with polymer morphology and are important for BHJ performance.
{"title":"Traps, morphology and degradation in high efficiency polymer solar cells","authors":"Z. Beiley, Craig H. Peters, I. T. Sachs-Quitana, E. Hoke, G. F. Burkhard, M. McGehee","doi":"10.1109/PVSC.2011.6185950","DOIUrl":"https://doi.org/10.1109/PVSC.2011.6185950","url":null,"abstract":"Bulk heterojunction solar cells (BHJs) based on poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) can have internal quantum efficiencies approaching 100% but require active layers that are too thin to absorb more than ∼70% of the above bandgap light.[1] In this work, we demonstrate that PCDTBT films contain a high density of hole-traps, which correlate with polymer morphology and are important for BHJ performance.","PeriodicalId":373149,"journal":{"name":"2011 37th IEEE Photovoltaic Specialists Conference","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128664940","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 : 2011-06-19DOI: 10.1109/PVSC.2011.6186152
Kyungsun Ryu, A. Upadhyaya, Arnab Das, S. Ramanathan, Y. Ok, Helen Xu, L. Metin, A. Bhanap, A. Rohatgi
Formation of boron emitters for mass production of low-cost and high efficiency n-type silicon solar cells is a major challenge in the PV industry. In this paper, we report on the successful fabrication of high efficiency screen-printed 19.3% n-type silicon cell with Voc of 646 mV, Jsc of 39.4 mA/cm2, and FF of 75.6 %, using boron dopant ink applied by inkjet printing to create boron-doped emitter. The detailed internal quantum efficiency (IQE) analysis showed excellent front surface recombination velocity (FSRV) of 15,000 cm/s and back surface recombination velocity (BSRV) of 66 cm/s. This demonstrates for the first time the promise of boron dopant ink for high performance n-type silicon solar cells.
{"title":"High efficiency n-type silicon solar cell with a novel inkjet-printed boron emitter","authors":"Kyungsun Ryu, A. Upadhyaya, Arnab Das, S. Ramanathan, Y. Ok, Helen Xu, L. Metin, A. Bhanap, A. Rohatgi","doi":"10.1109/PVSC.2011.6186152","DOIUrl":"https://doi.org/10.1109/PVSC.2011.6186152","url":null,"abstract":"Formation of boron emitters for mass production of low-cost and high efficiency n-type silicon solar cells is a major challenge in the PV industry. In this paper, we report on the successful fabrication of high efficiency screen-printed 19.3% n-type silicon cell with Voc of 646 mV, Jsc of 39.4 mA/cm2, and FF of 75.6 %, using boron dopant ink applied by inkjet printing to create boron-doped emitter. The detailed internal quantum efficiency (IQE) analysis showed excellent front surface recombination velocity (FSRV) of 15,000 cm/s and back surface recombination velocity (BSRV) of 66 cm/s. This demonstrates for the first time the promise of boron dopant ink for high performance n-type silicon solar cells.","PeriodicalId":373149,"journal":{"name":"2011 37th IEEE Photovoltaic Specialists Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124726288","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 : 2011-06-19DOI: 10.1109/PVSC.2011.6186571
D. Bobela, C. Teplin, D. Young, H. Branz, P. Stradins
We have grown device-quality epitaxial silicon thin films at growth rates up to 1.85 μm/min, using hot-wire chemical vapor deposition from silane, at substrate temperatures below 750°C. At these rates, which are more than 30 times faster than those used by the amorphous and nanocrystalline Si industry, capital costs for large-scale solar cell production would be dramatically reduced, even for cell absorber layers up to 10 μm thick. We achieved high growth rates by optimizing the three key parameters: silane flow, depletion, and filament geometry, based on our model developed earlier. Hydrogen coverage of the filament surface likely limits silane decomposition and growth rate at high system pressures. No considerable deterioration in PV device performance is observed when grown at high rate, provided that the epitaxial growth is initiated at low rate. A simple mesa device structure (wafer/epi Si/a-Si(i)/a-Si:H(p)/ITO) with a 2.3 μm thick epitaxial silicon absorber layer was grown at 0.7 μm/min. The finished device had an open-circuit voltage of 0.424 V without hydrogenation treatment.
我们利用硅烷的热线化学气相沉积技术，在低于750℃的衬底温度下，以高达1.85 μm/min的生长速率生长出器件级外延硅薄膜。在这些速度下，比非晶硅和纳米晶硅工业使用的速度快30多倍，大规模太阳能电池生产的资本成本将大大降低，即使是10 μm厚的电池吸收层。基于我们之前开发的模型，我们通过优化三个关键参数:硅烷流动、耗竭和长丝几何形状，实现了高增长率。在高系统压力下，丝表面的氢覆盖可能会限制硅烷的分解和生长速度。当以高速率生长时，如果外延生长以低速率开始，则不会观察到PV器件性能的显着恶化。以0.7 μm/min的速度生长出具有2.3 μm厚外延硅吸收层的简单台面器件结构(wafer/epi Si/ A -Si(i)/ A -Si:H(p)/ITO)。成品无加氢处理，开路电压0.424 V。
{"title":"Epitaxial crystal silicon absorber layers and solar cells grown at 1.8 microns per minute","authors":"D. Bobela, C. Teplin, D. Young, H. Branz, P. Stradins","doi":"10.1109/PVSC.2011.6186571","DOIUrl":"https://doi.org/10.1109/PVSC.2011.6186571","url":null,"abstract":"We have grown device-quality epitaxial silicon thin films at growth rates up to 1.85 μm/min, using hot-wire chemical vapor deposition from silane, at substrate temperatures below 750°C. At these rates, which are more than 30 times faster than those used by the amorphous and nanocrystalline Si industry, capital costs for large-scale solar cell production would be dramatically reduced, even for cell absorber layers up to 10 μm thick. We achieved high growth rates by optimizing the three key parameters: silane flow, depletion, and filament geometry, based on our model developed earlier. Hydrogen coverage of the filament surface likely limits silane decomposition and growth rate at high system pressures. No considerable deterioration in PV device performance is observed when grown at high rate, provided that the epitaxial growth is initiated at low rate. A simple mesa device structure (wafer/epi Si/a-Si(i)/a-Si:H(p)/ITO) with a 2.3 μm thick epitaxial silicon absorber layer was grown at 0.7 μm/min. The finished device had an open-circuit voltage of 0.424 V without hydrogenation treatment.","PeriodicalId":373149,"journal":{"name":"2011 37th IEEE Photovoltaic Specialists Conference","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129698233","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 silicon thin film solar module (TFSM) is gaining popularity over crystalline silicon (c-Si) solar modules because of it's less energy consumption during production, only 1% amount of silicon is needed, superior low light performance and low temperature coefficient. The traditional silicon TFSM is all solar cells series connected configuration which can be easily achieved through laser scribing process; however, the all series connected configuration results in high module voltage (Vmpp ∼ 96V) and non-optimized module output power due to the current limit issue. To reduce the PV system installation cost, it is necessary to have the low voltage TFSM comparable to c-Si solar module. In this study, we present the development of 1.3×1.1m2 parallel-and-series connected low voltage (Vmpp∼32V) silicon TFSM, called Auria Solar C-series module (patent pending). The C-series module also passed the IEC 61646 and 61730 qualification tests by TÜV Rheinland certification. Through the analysis of the current limit issue of the silicon TFSM, we optimize the solar cell numbers to get the best module output power. The small dead zone width ∼180μm (from P1 edge to P3 edge) achieved via the precise laser scribing is also shown in this paper. The comparison of module performance between C-series module and traditional TFSM reveals that C-series module has 1.5% higher Pmpp output. The 900kWp system using the C-series module was installed in Verona, Italy; the PVsyst simulation shows high energy yield and 92.1% high performance ratio.
硅薄膜太阳能组件(TFSM)比晶体硅太阳能组件(c-Si)更受欢迎，因为它在生产过程中能耗更低，只需要1%的硅，优越的弱光性能和低温度系数。传统的硅TFSM是所有太阳能电池串联连接的配置，可以很容易地通过激光划线工艺实现;然而，由于电流限制问题，全串联连接配置导致模块电压高(Vmpp ~ 96V)且模块输出功率未优化。为了降低光伏系统的安装成本，有必要采用与c-Si太阳能组件相当的低压TFSM。在这项研究中，我们介绍了1.3×1.1m2并联串联低压(Vmpp ~ 32V)硅TFSM的开发，称为Auria Solar c系列模块(正在申请专利)。c系列模块还通过了TÜV莱茵认证的IEC 61646和61730资格测试。通过分析硅TFSM的电流限制问题，优化太阳能电池的数量以获得最佳的组件输出功率。本文还展示了通过精确激光刻划获得的小死区宽度~ 180μm(从P1边缘到P3边缘)。c系列模块与传统TFSM的模块性能比较表明，c系列模块的Pmpp输出提高1.5%。使用c系列模块的900kWp系统安装在意大利维罗纳;仿真结果表明，该系统具有较高的能量产出率和92.1%的高性能。
{"title":"Low voltage and high energy yield thin film solar module","authors":"Zhen-Liang Liao, Yu-Chun Peng, Yi-Kai Lin, Ching-Ying Chang, Pei-Hua Tsai, Chih-Hsiung Chang, Kun-Chin Lin, Chin-Yao Tsai","doi":"10.1109/PVSC.2011.6186036","DOIUrl":"https://doi.org/10.1109/PVSC.2011.6186036","url":null,"abstract":"The silicon thin film solar module (TFSM) is gaining popularity over crystalline silicon (c-Si) solar modules because of it's less energy consumption during production, only 1% amount of silicon is needed, superior low light performance and low temperature coefficient. The traditional silicon TFSM is all solar cells series connected configuration which can be easily achieved through laser scribing process; however, the all series connected configuration results in high module voltage (Vmpp ∼ 96V) and non-optimized module output power due to the current limit issue. To reduce the PV system installation cost, it is necessary to have the low voltage TFSM comparable to c-Si solar module. In this study, we present the development of 1.3×1.1m2 parallel-and-series connected low voltage (Vmpp∼32V) silicon TFSM, called Auria Solar C-series module (patent pending). The C-series module also passed the IEC 61646 and 61730 qualification tests by TÜV Rheinland certification. Through the analysis of the current limit issue of the silicon TFSM, we optimize the solar cell numbers to get the best module output power. The small dead zone width ∼180μm (from P1 edge to P3 edge) achieved via the precise laser scribing is also shown in this paper. The comparison of module performance between C-series module and traditional TFSM reveals that C-series module has 1.5% higher Pmpp output. The 900kWp system using the C-series module was installed in Verona, Italy; the PVsyst simulation shows high energy yield and 92.1% high performance ratio.","PeriodicalId":373149,"journal":{"name":"2011 37th IEEE Photovoltaic Specialists Conference","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126683194","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 : 2011-06-19DOI: 10.1109/PVSC.2011.6186270
F. Chang, T. Chen, Bo-yu Huang, R. Ahrenkiel, P. Yu
Silicon nanowire (SiNW) arrays have become a promising structure for photovoltaics in which the surface recombination velocity is an important parameter. In this study, a simple and cost-effective method is presented for producing large-area SiNW arrays with various lengths. We then employ an optical technique based on resonant-coupled photoconductive decay (RCPCD) to provide a contactless measurement for the determination of the surface velocity and bulk lifetime of SiNW arrays. The basic method is to probe the decay of total excess carrier concentration by varying the excitation wavelengths. However, as the initial carrier distribution could be very complicated in SiNWs, we have developed a rigorous couple wave analysis (RCWA) to calculate the absorption of SiNWs in order to obtain the initial distribution of excess carriers. The total excess carrier concentration as a function of time can then be derived by using the simulation results for experimental curve fitting. The model successfully fits the measured data and extracts parameters, which helps to determine both the bulk lifetime and the surface recombination velocity.
{"title":"Optical technique for determining surface recombination velocity and bulk lifetime in silicon nanowire arrays","authors":"F. Chang, T. Chen, Bo-yu Huang, R. Ahrenkiel, P. Yu","doi":"10.1109/PVSC.2011.6186270","DOIUrl":"https://doi.org/10.1109/PVSC.2011.6186270","url":null,"abstract":"Silicon nanowire (SiNW) arrays have become a promising structure for photovoltaics in which the surface recombination velocity is an important parameter. In this study, a simple and cost-effective method is presented for producing large-area SiNW arrays with various lengths. We then employ an optical technique based on resonant-coupled photoconductive decay (RCPCD) to provide a contactless measurement for the determination of the surface velocity and bulk lifetime of SiNW arrays. The basic method is to probe the decay of total excess carrier concentration by varying the excitation wavelengths. However, as the initial carrier distribution could be very complicated in SiNWs, we have developed a rigorous couple wave analysis (RCWA) to calculate the absorption of SiNWs in order to obtain the initial distribution of excess carriers. The total excess carrier concentration as a function of time can then be derived by using the simulation results for experimental curve fitting. The model successfully fits the measured data and extracts parameters, which helps to determine both the bulk lifetime and the surface recombination velocity.","PeriodicalId":373149,"journal":{"name":"2011 37th IEEE Photovoltaic Specialists Conference","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129217689","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 : 2011-06-19DOI: 10.1109/PVSC.2011.6186180
T. Aviles, C. Lethien, M. Zegaoui, J. Vilcot, F. Leroy, P. Roussel, N. Rolland, P. Rolland
In this paper, we report on the study of electrical, optical and structural properties of RF sputtered Indium Tin Oxide (ITO) thin films at room temperature. These films are dedicated to act as front electrode of CIGS solar microcells and shall so compel with the electrical and optical criteria that are required for such an application. It is well-known that the main drawback of the sputtering deposition technique deals with the inherent generation of highly energetic particles that causes bombardment onto the sample. The developed deposition process targets to be damage free onto the underlying layer since, in the case of CIGS solar cells, it is crucial to preserve the surface and the properties of the absorber layer on which these films will be deposited. At room temperature, it can be considered that amorphous ITO films are only obtained when this energetic bombardment does not occur. This can be obtained if the kinetic energy of the particles is fully dissipated by collisions within the deposition plasma [1–3]. The deposition process is developed in a conventional magnetron sputtering system without external heating, in such a way that films shall be amorphous. Furthermore, film internal stress is kept very low. Optical studies show a transparency over 80% in the visible range and a high transparency in the infrared region. The lowest obtained sheet resistance is 12.6 Ω/□ (∼ 300nm film thickness) with a carrier concentration of 2.4 × 1020 cm−3 and a carrier mobility of 45.1 cm2/V.s. As we can deposit a dual ITO layer structure, with a different resistivity level being attributed to each layer, we suggest our amorphous ITO thin films can be deposited directly above the absorbing CIGS material to act as both highly resistive (HR) and electrode layer.
{"title":"Recent developments in amorphous sputterred ITO thin films acting as transparent front contact layer of CIGS solar cells for energy autonomous wireless microsystems","authors":"T. Aviles, C. Lethien, M. Zegaoui, J. Vilcot, F. Leroy, P. Roussel, N. Rolland, P. Rolland","doi":"10.1109/PVSC.2011.6186180","DOIUrl":"https://doi.org/10.1109/PVSC.2011.6186180","url":null,"abstract":"In this paper, we report on the study of electrical, optical and structural properties of RF sputtered Indium Tin Oxide (ITO) thin films at room temperature. These films are dedicated to act as front electrode of CIGS solar microcells and shall so compel with the electrical and optical criteria that are required for such an application. It is well-known that the main drawback of the sputtering deposition technique deals with the inherent generation of highly energetic particles that causes bombardment onto the sample. The developed deposition process targets to be damage free onto the underlying layer since, in the case of CIGS solar cells, it is crucial to preserve the surface and the properties of the absorber layer on which these films will be deposited. At room temperature, it can be considered that amorphous ITO films are only obtained when this energetic bombardment does not occur. This can be obtained if the kinetic energy of the particles is fully dissipated by collisions within the deposition plasma [1–3]. The deposition process is developed in a conventional magnetron sputtering system without external heating, in such a way that films shall be amorphous. Furthermore, film internal stress is kept very low. Optical studies show a transparency over 80% in the visible range and a high transparency in the infrared region. The lowest obtained sheet resistance is 12.6 Ω/□ (∼ 300nm film thickness) with a carrier concentration of 2.4 × 1020 cm−3 and a carrier mobility of 45.1 cm2/V.s. As we can deposit a dual ITO layer structure, with a different resistivity level being attributed to each layer, we suggest our amorphous ITO thin films can be deposited directly above the absorbing CIGS material to act as both highly resistive (HR) and electrode layer.","PeriodicalId":373149,"journal":{"name":"2011 37th IEEE Photovoltaic Specialists Conference","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123797225","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 : 2011-06-19DOI: 10.1109/PVSC.2011.6186341
J. Weber, K. Bertness, J. Schlager, N. Sanford, A. Imtiaz, T. M. Wallis, P. Kabos, K. Coakley, V. Bright, L. Mansfield
The photoresponse of three different photovoltaic Cu(In, Ga)Se2 (CIGS) samples as well as GaAs and silicon bulk samples is measured using near-field scanning microwave microscopy (NSMM). Modeling predicts light-dependent conductivity values for bulk samples, as well as a preliminary understanding of more complicated multilayer photovoltaics. The spectral dependence of CIGS samples is probed at 405, 635, 808 and 980 nm wavelengths. In addition, we present two-dimensional raster scans that may reveal grain-boundary effects under illumination.
{"title":"Microwave near-field probes for photovoltaic applications","authors":"J. Weber, K. Bertness, J. Schlager, N. Sanford, A. Imtiaz, T. M. Wallis, P. Kabos, K. Coakley, V. Bright, L. Mansfield","doi":"10.1109/PVSC.2011.6186341","DOIUrl":"https://doi.org/10.1109/PVSC.2011.6186341","url":null,"abstract":"The photoresponse of three different photovoltaic Cu(In, Ga)Se2 (CIGS) samples as well as GaAs and silicon bulk samples is measured using near-field scanning microwave microscopy (NSMM). Modeling predicts light-dependent conductivity values for bulk samples, as well as a preliminary understanding of more complicated multilayer photovoltaics. The spectral dependence of CIGS samples is probed at 405, 635, 808 and 980 nm wavelengths. In addition, we present two-dimensional raster scans that may reveal grain-boundary effects under illumination.","PeriodicalId":373149,"journal":{"name":"2011 37th IEEE Photovoltaic Specialists Conference","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123809672","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 : 2011-06-19DOI: 10.1109/PVSC.2011.6186300
M. Coddington, B. Kroposki, Thomas Basso, D. Berger, Kristin Crowell, J. Hayes
In 2008, a 300 kWpeak photovoltaic (PV) system was installed on the rooftop of the Colorado Convention Center (CCC). The installation was unique for the electric utility, Xcel Energy, as it had not previously permitted a PV system to be interconnected on a building served by the local secondary network distribution system (network). The PV system was installed with several provisions; one to prevent reverse power flow, another called a dynamically controlled inverter (DCI), that curtails the output of the PV inverters to maintain an amount of load supplied by Xcel Energy at the CCC. The DCI system utilizes current transformers (CTs) to sense power flow to insure that a minimum threshold is maintained from Xcel Energy through the network transformers. The inverters are set to track the load on each of the three phases and curtail power from the PV system when the generated PV system current reaches 95% of the current on any phase. This is achieved by the DCI, which gathers inputs from current transformers measuring the current from the PV array, Xcel, and the spot network load. Preventing reverse power flow is a critical technical requirement for the spot network which serve this part of the CCC. The PV system was designed with the expectation that the DCI system would not curtail the PV system, as the expected minimum load consumption was historically higher than the designed PV system size. However, the DCI system has operated many days during the course of a year, and the performance has been excellent. The DCI system at the CCC was installed as a secondary measure to insure that a minimum level of power flows to the CCC from the Xcel Energy network. While this DCI system was intended for localized control, the system could also reduce output percent if an external smart grid control signal was employed. This paper specifically focuses on the performance of the innovative design at this installation; however, the DCI system could also be used for new smart grid-enabled distribution systems where renewables power contributions at certain conditions or times may need to be curtailed.
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