Pub Date : 2016-11-21DOI: 10.1109/PVSC.2016.7749947
Yun Xue, M. Todd, S. Ula, M. Barth, A. Martinez-Morales
This paper describes an evaluation between two model predictive control (MPC) algorithms for microgrid energy management combined with solar production and battery energy storage for demand charge reduction in a real-world microgrid system. The first control algorithm is a constant threshold MPC (CT-MPC) that works well on a system with relatively stable solar generation and a well-known building load profile. CT-MPC can maintain the on-peak demand under a certain value during the entire on-peak rate period. The second control algorithm is an adjusting demand threshold MPC (ADT-MPC). ADT-MPC can better deal with unpredictable solar generation and/or changing building loads. The on-peak threshold under this algorithm is adjusted to the optimal value during the on-peak rate period. As expected, The CT-MPC algorithm performs well when coupled with accurate forecast models while the ADT-MPC algorithm excels when forecasting is more unpredictable.
{"title":"A comparison between two MPC algorithms for demand charge reduction in a real-world microgrid system","authors":"Yun Xue, M. Todd, S. Ula, M. Barth, A. Martinez-Morales","doi":"10.1109/PVSC.2016.7749947","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7749947","url":null,"abstract":"This paper describes an evaluation between two model predictive control (MPC) algorithms for microgrid energy management combined with solar production and battery energy storage for demand charge reduction in a real-world microgrid system. The first control algorithm is a constant threshold MPC (CT-MPC) that works well on a system with relatively stable solar generation and a well-known building load profile. CT-MPC can maintain the on-peak demand under a certain value during the entire on-peak rate period. The second control algorithm is an adjusting demand threshold MPC (ADT-MPC). ADT-MPC can better deal with unpredictable solar generation and/or changing building loads. The on-peak threshold under this algorithm is adjusted to the optimal value during the on-peak rate period. As expected, The CT-MPC algorithm performs well when coupled with accurate forecast models while the ADT-MPC algorithm excels when forecasting is more unpredictable.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82884505","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 : 2016-11-21DOI: 10.1109/PVSC.2016.7750298
A. Mellor, N. P. Hylton, C. Wellens, T. Thomas, Y. Al-Saleh, V. Giannini, A. Braun, H. Hauser, S. Maier, N. Ekins‐Daukes
We show that the radiation-hardness of space solar cells can be significantly improved by employing nanophotonic light trapping. Two light-trapping structures are investigated in this work. In the first, an array of Al nanoparticles is embedded within the anti-reflection coating of a GaInP/InGaAs/Ge solar cell. A combined experimental and simulation study shows that this structure is unlikely to lead to an improvement in radiation hardness. In the second, a diffractive structure is positioned between the middle cell and the bottom cell. Computational results, obtained using an experimentally validated electro-optical simulation tool, show that a properly designed light-trapping structure in this position can lead to a relative 10% improvement in the middle-cell photocurrent at end-of-life.
{"title":"Improving the radiation hardness of space solar cells via nanophotonic light trapping","authors":"A. Mellor, N. P. Hylton, C. Wellens, T. Thomas, Y. Al-Saleh, V. Giannini, A. Braun, H. Hauser, S. Maier, N. Ekins‐Daukes","doi":"10.1109/PVSC.2016.7750298","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750298","url":null,"abstract":"We show that the radiation-hardness of space solar cells can be significantly improved by employing nanophotonic light trapping. Two light-trapping structures are investigated in this work. In the first, an array of Al nanoparticles is embedded within the anti-reflection coating of a GaInP/InGaAs/Ge solar cell. A combined experimental and simulation study shows that this structure is unlikely to lead to an improvement in radiation hardness. In the second, a diffractive structure is positioned between the middle cell and the bottom cell. Computational results, obtained using an experimentally validated electro-optical simulation tool, show that a properly designed light-trapping structure in this position can lead to a relative 10% improvement in the middle-cell photocurrent at end-of-life.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81564765","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 : 2016-11-21DOI: 10.1109/PVSC.2016.7750158
T. Guan, Grant Klafehn, C. Kendrick, San Theingi, Idemudia Airuoyo, M. Lusk, P. Stradins, Craig J Taylor, R. Collins
Mixed phase nanocrystalline/amorphous-silicon (nc/a-Si:H) thin films with band-gap higher than bulk silicon are prepared by depositing silicon nanoparticles (SiNPs), prepared in a separate deposition zone, and hydrogenated amorphous silicon (a-Si:H), simultaneously. Since the two deposition phases are well decoupled, optimized parameters for each component can apply to the growth process. Photoluminescence spectroscopy (PL) shows that the embedded SiNPs are small enough to exhibit quantum confinement effects. The low temperature PL measurements on the mixed phase reveal a dominant emission feature, which is associated with SiNPs surrounded by a-Si:H. In addition, we compare time dependent low temperature PL measurements for both a-Si:H and mixed phase material under intensive laser exposure for various times up to two hours. The PL intensity of a-Si:H with embedded SiNPs degrades much less than that of pure a-Si:H. We propose this improvement of photostability occurs because carriers generated in the a-Si:H matrix quickly transfer into SiNPs and recombine there instead of recombining in a-Si:H and creating defect states (Staebler-Wronski Effect).
{"title":"Bandgap and carrier transport engineering of quantum confined mixed phase nanocrystalline/amorphous silicon","authors":"T. Guan, Grant Klafehn, C. Kendrick, San Theingi, Idemudia Airuoyo, M. Lusk, P. Stradins, Craig J Taylor, R. Collins","doi":"10.1109/PVSC.2016.7750158","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750158","url":null,"abstract":"Mixed phase nanocrystalline/amorphous-silicon (nc/a-Si:H) thin films with band-gap higher than bulk silicon are prepared by depositing silicon nanoparticles (SiNPs), prepared in a separate deposition zone, and hydrogenated amorphous silicon (a-Si:H), simultaneously. Since the two deposition phases are well decoupled, optimized parameters for each component can apply to the growth process. Photoluminescence spectroscopy (PL) shows that the embedded SiNPs are small enough to exhibit quantum confinement effects. The low temperature PL measurements on the mixed phase reveal a dominant emission feature, which is associated with SiNPs surrounded by a-Si:H. In addition, we compare time dependent low temperature PL measurements for both a-Si:H and mixed phase material under intensive laser exposure for various times up to two hours. The PL intensity of a-Si:H with embedded SiNPs degrades much less than that of pure a-Si:H. We propose this improvement of photostability occurs because carriers generated in the a-Si:H matrix quickly transfer into SiNPs and recombine there instead of recombining in a-Si:H and creating defect states (Staebler-Wronski Effect).","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80502326","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 : 2016-11-21DOI: 10.1109/PVSC.2016.7749987
S. Essig, C. Allébe, J. Geisz, M. Steiner, B. Paviet‐Salomon, A. Descoeudres, A. Tamboli, L. Barraud, S. Ward, N. Badel, V. LaSalvia, J. Levrat, M. Despeisse, C. Ballif, P. Stradins, D. Young
We have developed Si-based tandem solar cells with a certified 1-sun efficiency of 29.8% (AM1.5g). The four-terminal tandem devices consist of 1.8 eV rear-heterojunction GaInP top cells and silicon heterojunction bottom cells. The two subcells were fabricated independently in two different labs and merged using an optically transparent, electrically insulating epoxy. Work is ongoing to further improve the performance of each subcell and to push the tandem cell efficiency to > 30%.
{"title":"Boosting the efficiency of III-V/Si tandem solar cells","authors":"S. Essig, C. Allébe, J. Geisz, M. Steiner, B. Paviet‐Salomon, A. Descoeudres, A. Tamboli, L. Barraud, S. Ward, N. Badel, V. LaSalvia, J. Levrat, M. Despeisse, C. Ballif, P. Stradins, D. Young","doi":"10.1109/PVSC.2016.7749987","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7749987","url":null,"abstract":"We have developed Si-based tandem solar cells with a certified 1-sun efficiency of 29.8% (AM1.5g). The four-terminal tandem devices consist of 1.8 eV rear-heterojunction GaInP top cells and silicon heterojunction bottom cells. The two subcells were fabricated independently in two different labs and merged using an optically transparent, electrically insulating epoxy. Work is ongoing to further improve the performance of each subcell and to push the tandem cell efficiency to > 30%.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76730525","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 : 2016-11-21DOI: 10.1109/PVSC.2016.7750024
V. Kheraj, E. Lund, A. E. Caruso, K. Al-Ajmi, D. Pruzan, C. Miskin, R. Agrawal, C. Beall, I. Repins, M. Scarpulla
We report observations of minority carrier interactions with deep levels in 6-8% efficient Cu2ZnSn(S, Se)4 (CZTSSe) devices using conventional and minority deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS). Directly observing defect interactions with minority carriers is critical to understanding the recombination impact of deep levels. In devices with Cu2ZnSn(S, Se)4 nanoparticle ink absorber layers we identify a mid-gap state capturing and emitting minority electrons. It is 590±50 meV from the conduction band mobility edge, has a concentration near 1015/cm3, and has an apparent electron capture cross section ~10-14 cm2. We conclude that, while energetically positioned nearly-ideally to be a recombination center, these defects instead act as electron traps because of a smaller hole cross-section. In CZTSe devices produced using coevaporation, we used minority carrier DLTS on traditional samples as well as ones with transparent Ohmic back contacts. These experiments demonstrate methods for unambiguously probing minority carrier/defect interactions in solar cells in order to establish direct links between defect energy level observations and minority carrier lifetimes. Furthermore, we demonstrate the use of steady-state device simulation to aid in the interpretation of DLTS results e.g. to put bounds on the complimentary carrier cross section even in the absence its direct measurement. This combined experimental and theoretical approach establishes rigorous bounds on the impact on carrier lifetime and Voc of defects observed with DLTS as opposed to, for example, assuming that all deep states act as strong recombination centers.
{"title":"Minority carrier electron traps in CZTSSe solar cells characterized by DLTS and DLOS","authors":"V. Kheraj, E. Lund, A. E. Caruso, K. Al-Ajmi, D. Pruzan, C. Miskin, R. Agrawal, C. Beall, I. Repins, M. Scarpulla","doi":"10.1109/PVSC.2016.7750024","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750024","url":null,"abstract":"We report observations of minority carrier interactions with deep levels in 6-8% efficient Cu2ZnSn(S, Se)4 (CZTSSe) devices using conventional and minority deep level transient spectroscopy (DLTS) and deep level optical spectroscopy (DLOS). Directly observing defect interactions with minority carriers is critical to understanding the recombination impact of deep levels. In devices with Cu2ZnSn(S, Se)4 nanoparticle ink absorber layers we identify a mid-gap state capturing and emitting minority electrons. It is 590±50 meV from the conduction band mobility edge, has a concentration near 1015/cm3, and has an apparent electron capture cross section ~10-14 cm2. We conclude that, while energetically positioned nearly-ideally to be a recombination center, these defects instead act as electron traps because of a smaller hole cross-section. In CZTSe devices produced using coevaporation, we used minority carrier DLTS on traditional samples as well as ones with transparent Ohmic back contacts. These experiments demonstrate methods for unambiguously probing minority carrier/defect interactions in solar cells in order to establish direct links between defect energy level observations and minority carrier lifetimes. Furthermore, we demonstrate the use of steady-state device simulation to aid in the interpretation of DLTS results e.g. to put bounds on the complimentary carrier cross section even in the absence its direct measurement. This combined experimental and theoretical approach establishes rigorous bounds on the impact on carrier lifetime and Voc of defects observed with DLTS as opposed to, for example, assuming that all deep states act as strong recombination centers.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89242932","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 : 2016-11-21DOI: 10.1109/PVSC.2016.7749574
M. Neuschitzer, S. Giraldo, J. Márquez, M. Dimitrievska, M. Placidi, I. Forbes, V. Izquierdo‐Roca, A. Pérez‐Rodríguez, E. Saucedo
In this study we present beneficial effects on the device performance with a Ge-assisted crystallization of nanocrystalline CZTSe precursors. For low Ge content layers, an increase in doping density is observed, which results in 8.6% efficiency devices and Voc values of above 470 mV, corresponding to Voc deficits of 583 mV, comparable to current record devices. High Ge content layers exhibit enhanced grain growth, however, they are also associated with deterioration in cell performance. Admittance spectroscopy measurements identified the appearance of a deep defect for high Ge doping. These results indicate that an accurate control of group IV (Ge, Sn) elemental composition seems mandatory for high device performance.
{"title":"Enhancing grain growth and boosting Voc in CZTSe absorber layers — Is Ge doping the answer?","authors":"M. Neuschitzer, S. Giraldo, J. Márquez, M. Dimitrievska, M. Placidi, I. Forbes, V. Izquierdo‐Roca, A. Pérez‐Rodríguez, E. Saucedo","doi":"10.1109/PVSC.2016.7749574","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7749574","url":null,"abstract":"In this study we present beneficial effects on the device performance with a Ge-assisted crystallization of nanocrystalline CZTSe precursors. For low Ge content layers, an increase in doping density is observed, which results in 8.6% efficiency devices and Voc values of above 470 mV, corresponding to Voc deficits of 583 mV, comparable to current record devices. High Ge content layers exhibit enhanced grain growth, however, they are also associated with deterioration in cell performance. Admittance spectroscopy measurements identified the appearance of a deep defect for high Ge doping. These results indicate that an accurate control of group IV (Ge, Sn) elemental composition seems mandatory for high device performance.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87897285","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 : 2016-11-18DOI: 10.1109/PVSC.2016.7750205
Päivikki Repo, Yameng Bao, Heli Seppanen, Perttu Sippola, H. Savin
We propose a new surface passivation material for crystalline silicon solar cells, namely atomic layer deposited aluminium nitride (ALD AlN). AlN has multiple benefits as compared to more commonly used Al2O3, i.e. it has better optical properties, higher hydrogen concentration and better suitability for phosphorous emitter passivation due to lower fixed charge. In addition to introducing a new ALD passivation material, we study here various deposition temperatures and postdeposition heat treatments. The best surface passivation quality is reached with high deposition temperatures followed by a combination of longer low temperature anneal and a short high temperature firing. With the optimized parameters, extremely low interface defect density values of ~4·1011 eV-1cm-2 are reached demonstrating the potential of ALD AlN as future surface passivation material.
{"title":"Silicon surface passivation with atomic layer deposited aluminum nitride","authors":"Päivikki Repo, Yameng Bao, Heli Seppanen, Perttu Sippola, H. Savin","doi":"10.1109/PVSC.2016.7750205","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750205","url":null,"abstract":"We propose a new surface passivation material for crystalline silicon solar cells, namely atomic layer deposited aluminium nitride (ALD AlN). AlN has multiple benefits as compared to more commonly used Al2O3, i.e. it has better optical properties, higher hydrogen concentration and better suitability for phosphorous emitter passivation due to lower fixed charge. In addition to introducing a new ALD passivation material, we study here various deposition temperatures and postdeposition heat treatments. The best surface passivation quality is reached with high deposition temperatures followed by a combination of longer low temperature anneal and a short high temperature firing. With the optimized parameters, extremely low interface defect density values of ~4·1011 eV-1cm-2 are reached demonstrating the potential of ALD AlN as future surface passivation material.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83914087","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 : 2016-11-18DOI: 10.1109/PVSC.2016.7749649
A. Uruno, M. Kobayashi
The AgGaTe2 layer was formed on Ag2Te/Si structure with two different procedures by eliminating the melt-back etching. Diffusion of the Ga2Te3 source material into the Ag2Te layer and formation of the AgGaTe2 layer were both occurring during the growth when Ag2Te and Ga2Te3 source mixture was used to form AgGaTe2. It was also clear the AgGaTe2 could be formed by deposition and annealing of Ga2Te3 layer on top of the Ag2Te/Si structure. Solar cells were fabricated using the p-AgGaTe2/n-Si heterojunction, and showed conversion efficiency of approximately 3%.
{"title":"The growth of AgGaTe2 layer on Si substrate by two-step closed space sublimation and its application to solar cell fabrications","authors":"A. Uruno, M. Kobayashi","doi":"10.1109/PVSC.2016.7749649","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7749649","url":null,"abstract":"The AgGaTe<sub>2</sub> layer was formed on Ag<sub>2</sub>Te/Si structure with two different procedures by eliminating the melt-back etching. Diffusion of the Ga<sub>2</sub>Te<sub>3</sub> source material into the Ag<sub>2</sub>Te layer and formation of the AgGaTe<sub>2</sub> layer were both occurring during the growth when Ag<sub>2</sub>Te and Ga<sub>2</sub>Te<sub>3</sub> source mixture was used to form AgGaTe<sub>2</sub>. It was also clear the AgGaTe<sub>2</sub> could be formed by deposition and annealing of Ga<sub>2</sub>Te<sub>3</sub> layer on top of the Ag<sub>2</sub>Te/Si structure. Solar cells were fabricated using the p-AgGaTe<sub>2</sub>/n-Si heterojunction, and showed conversion efficiency of approximately 3%.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78462226","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 : 2016-11-18DOI: 10.1109/PVSC.2016.7750025
Mark J. Koeper, C. Hages, Jian V. Li, D. Levi, R. Agrawal
Admittance spectroscopy has been performed on a CZTSSe device with a carrier injection pretreatment and under electronically relaxed conditions to demonstrate metastability behavior. We show that the measurements with the carrier injection pretreatment demonstrate two admittance signatures while the relaxed measurement demonstrates only one admittance signature with a different activation energy. Additionally, voltage dependent admittance spectroscopy was performed using the carrier injection pretreatment method at each of the applied voltage bias. The activation energies of the two admittance signatures were calculated and are shown to be independent of the voltage bias.
{"title":"Admittance spectroscopy in CZTSSe: Metastability behavior and voltage dependent defect study","authors":"Mark J. Koeper, C. Hages, Jian V. Li, D. Levi, R. Agrawal","doi":"10.1109/PVSC.2016.7750025","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750025","url":null,"abstract":"Admittance spectroscopy has been performed on a CZTSSe device with a carrier injection pretreatment and under electronically relaxed conditions to demonstrate metastability behavior. We show that the measurements with the carrier injection pretreatment demonstrate two admittance signatures while the relaxed measurement demonstrates only one admittance signature with a different activation energy. Additionally, voltage dependent admittance spectroscopy was performed using the carrier injection pretreatment method at each of the applied voltage bias. The activation energies of the two admittance signatures were calculated and are shown to be independent of the voltage bias.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90399895","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 : 2016-11-18DOI: 10.1109/PVSC.2016.7750169
T. Tanaka, S. Tsutsumi, Y. Okano, K. Saito, Q. Guo, M. Nishio, K. Yu, W. Walukiewicz
We report the effect of Cl-doping in highly mismatched ZnTeO alloys grown on ZnTe substrate by molecular beam epitaxy using ZnCl2 as a dopant source in order to introduce electrons into the intermediate band of ZnTeO that is required to be half-filled with electrons for the efficient operation of an intermediate band solar cell. The ZnCl2 cell temperature was varied between 70 and 250 °C. In order to characterize the photoluminescence (PL) properties exactly, the temperature dependence of band gap energies for E+ and E- bands of ZnTeO was first determined by photoreflectance measurements. Changes in band gap energies were found to be in accordance with those expected by the band anticrossing model. In the low temperature PL spectra, a donor-acceptor pair emission was found, indicating the formation of Cl-related donors.
{"title":"Cl-doping in highly mismatched ZnTe1−xOx alloys for intermediate band solar cells","authors":"T. Tanaka, S. Tsutsumi, Y. Okano, K. Saito, Q. Guo, M. Nishio, K. Yu, W. Walukiewicz","doi":"10.1109/PVSC.2016.7750169","DOIUrl":"https://doi.org/10.1109/PVSC.2016.7750169","url":null,"abstract":"We report the effect of Cl-doping in highly mismatched ZnTeO alloys grown on ZnTe substrate by molecular beam epitaxy using ZnCl2 as a dopant source in order to introduce electrons into the intermediate band of ZnTeO that is required to be half-filled with electrons for the efficient operation of an intermediate band solar cell. The ZnCl2 cell temperature was varied between 70 and 250 °C. In order to characterize the photoluminescence (PL) properties exactly, the temperature dependence of band gap energies for E+ and E- bands of ZnTeO was first determined by photoreflectance measurements. Changes in band gap energies were found to be in accordance with those expected by the band anticrossing model. In the low temperature PL spectra, a donor-acceptor pair emission was found, indicating the formation of Cl-related donors.","PeriodicalId":6524,"journal":{"name":"2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2016-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78198920","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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