Pub Date : 2014-06-08DOI: 10.1109/PVSC.2014.6925392
B. Faulkner, J. Burst, T. Ohno, C. Perkins, B. To, T. Gessert
A back contact containing a sputtered ZnTe:Cu interface layer can produce high-performing thin-film CdS/CdTe photovoltaic devices. We have found that small changes in ZnTe:Cu sputtering target fabrication processes affect the properties of the ZnTe:Cu films, which affect the performance of the resulting devices. Different target manufacturing techniques were investigated to study changes in ZnTe:Cu film properties and how they impact device performance. Compositional, optical, and electrical properties of films made from different target recipes were studied. It was found that the amount of oxygen in the targets and films is strongly linked to changes in material properties, especially in band tailing and optical bandgap.
{"title":"ZnTe:Cu film properties and their impact on CdS/CdTe devices","authors":"B. Faulkner, J. Burst, T. Ohno, C. Perkins, B. To, T. Gessert","doi":"10.1109/PVSC.2014.6925392","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925392","url":null,"abstract":"A back contact containing a sputtered ZnTe:Cu interface layer can produce high-performing thin-film CdS/CdTe photovoltaic devices. We have found that small changes in ZnTe:Cu sputtering target fabrication processes affect the properties of the ZnTe:Cu films, which affect the performance of the resulting devices. Different target manufacturing techniques were investigated to study changes in ZnTe:Cu film properties and how they impact device performance. Compositional, optical, and electrical properties of films made from different target recipes were studied. It was found that the amount of oxygen in the targets and films is strongly linked to changes in material properties, especially in band tailing and optical bandgap.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"16 1","pages":"2321-2325"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74928126","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925548
J. Barredo, A. Fraile, C. Alarcon, L. Hermanns
The mechanical strength of drilled wafers, according to a EWT or MWT structure, is widely influenced by the presence of holes. In the study of the strength of these samples, the holes should be included in the simulations resulting in very heavy models with high calculation times. The traditional mechanical design for ductile materials with holes is based in the application of stress concentration factors. This method is not valid in this case due to the strength dependence on the size of the loaded area. In this paper, a stress concentration surface is proposed getting a much simpler approach for the simulations with drilled samples.
{"title":"A simple approach for the simulations in the mechanical studies of drilled wafers","authors":"J. Barredo, A. Fraile, C. Alarcon, L. Hermanns","doi":"10.1109/PVSC.2014.6925548","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925548","url":null,"abstract":"The mechanical strength of drilled wafers, according to a EWT or MWT structure, is widely influenced by the presence of holes. In the study of the strength of these samples, the holes should be included in the simulations resulting in very heavy models with high calculation times. The traditional mechanical design for ductile materials with holes is based in the application of stress concentration factors. This method is not valid in this case due to the strength dependence on the size of the loaded area. In this paper, a stress concentration surface is proposed getting a much simpler approach for the simulations with drilled samples.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"67 1","pages":"2941-2946"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73256435","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925676
E. Barrigón, P. Espinet-González, Y. Contreras, L. Barrutia, I. Rey‐Stolle, C. Algora
External quantum efficiency measurement of multijunction solar cells is not an easy task. In this paper we propose to trace the I-V curve of the multijunction device under the same light bias conditions intended to be applied for the EQE measurement as an effective way to minimize artifacts and determine the optimum light and voltage bias conditions for the measurement. In this way, the analysis of the I-V curve will help to determine the proper voltage bias needed (if any), as well as to distinguish whether the external quantum efficiency measurement is being affected by shunt problems, early breakdown or luminescent coupling. This is of special relevance in order to determine the origin of the measurement artifact affecting the external quantum efficiency measurement of MJSCs.
{"title":"On the use of I–V curves as a diagnosis tool for proper external quantum efficiency measurements of multijunction solar cells","authors":"E. Barrigón, P. Espinet-González, Y. Contreras, L. Barrutia, I. Rey‐Stolle, C. Algora","doi":"10.1109/PVSC.2014.6925676","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925676","url":null,"abstract":"External quantum efficiency measurement of multijunction solar cells is not an easy task. In this paper we propose to trace the I-V curve of the multijunction device under the same light bias conditions intended to be applied for the EQE measurement as an effective way to minimize artifacts and determine the optimum light and voltage bias conditions for the measurement. In this way, the analysis of the I-V curve will help to determine the proper voltage bias needed (if any), as well as to distinguish whether the external quantum efficiency measurement is being affected by shunt problems, early breakdown or luminescent coupling. This is of special relevance in order to determine the origin of the measurement artifact affecting the external quantum efficiency measurement of MJSCs.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"3 1","pages":"3453-3456"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75338559","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6924881
N. Shiradkar, E. Schneller, N. Dhere, V. Gade
Bypass diodes in photovoltaic (PV) modules can undergo thermal runaway while transitioning from forward bias state to reverse bias. Theoretical framework has been developed for predicting the susceptibility of bypass diodes to thermal runaway. The operating temperature of diode in forward bias is dependent on thermal resistance of diode-junction box system and the forward current through the diode. A new parameter -`critical temperature' (junction temperature at which forward power dissipation in diode equals reverse power dissipation for given forward current and reverse voltage) is introduced. Critical temperature is only dependent on the forward current through the diode and reverse voltage that would get applied to the diode in reverse bias. Critical temperature is shown to be independent of external factors such as thermal resistance of diode/junction box and ambient temperature. It is shown that the diode undergoes thermal runaway while transitioning from forward bias to reverse bias only if the operating diode junction temperature is greater than the critical temperature. Based on this understanding, a model is developed to predict vulnerability of various Schottky bypass diodes for thermal runaway as a function of thermal resistance and forward current. The results are experimentally verified using a specially developed setup for thermal runaway testing of bypass diodes.
{"title":"Predicting thermal runaway in bypass diodes in photovoltaic modules","authors":"N. Shiradkar, E. Schneller, N. Dhere, V. Gade","doi":"10.1109/PVSC.2014.6924881","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6924881","url":null,"abstract":"Bypass diodes in photovoltaic (PV) modules can undergo thermal runaway while transitioning from forward bias state to reverse bias. Theoretical framework has been developed for predicting the susceptibility of bypass diodes to thermal runaway. The operating temperature of diode in forward bias is dependent on thermal resistance of diode-junction box system and the forward current through the diode. A new parameter -`critical temperature' (junction temperature at which forward power dissipation in diode equals reverse power dissipation for given forward current and reverse voltage) is introduced. Critical temperature is only dependent on the forward current through the diode and reverse voltage that would get applied to the diode in reverse bias. Critical temperature is shown to be independent of external factors such as thermal resistance of diode/junction box and ambient temperature. It is shown that the diode undergoes thermal runaway while transitioning from forward bias to reverse bias only if the operating diode junction temperature is greater than the critical temperature. Based on this understanding, a model is developed to predict vulnerability of various Schottky bypass diodes for thermal runaway as a function of thermal resistance and forward current. The results are experimentally verified using a specially developed setup for thermal runaway testing of bypass diodes.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"43 1","pages":"3585-3588"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73687017","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925673
Neha Mahuli, S. Sarkar
In this report we have discussed the need of conformal deposition of the low bandgap materials as absorber in solid-state bulk heterojunction devices. We demonstrated ALD grown Sb2S3 and TiSx thin films for photovoltaic applications. The deposition mechanism was studied in depth using in-situ quartz crystal microbalance (QCM). Need of modified reactor configuration for the uniform deposition of the material throughout the depth of the mesoporous host was discussed with elaborated comparative results for various absorber material device configurations.
{"title":"ALD grown absorber materials for bulk heterojunction solar cells","authors":"Neha Mahuli, S. Sarkar","doi":"10.1109/PVSC.2014.6925673","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925673","url":null,"abstract":"In this report we have discussed the need of conformal deposition of the low bandgap materials as absorber in solid-state bulk heterojunction devices. We demonstrated ALD grown Sb2S3 and TiSx thin films for photovoltaic applications. The deposition mechanism was studied in depth using in-situ quartz crystal microbalance (QCM). Need of modified reactor configuration for the uniform deposition of the material throughout the depth of the mesoporous host was discussed with elaborated comparative results for various absorber material device configurations.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"23 1","pages":"0247-0249"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72722621","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925281
Jacob J. Becker, Ying-Shen Kuo, Yong-Hang Zhang
The absorber-thickness dependent, relative efficiency losses for solar cells with a 300 nm, 1000 nm and 2000 nm thick absorber were found to be 20.5%, 26.8% and 28.6%, respectively, after exposure to 1 MeV electron radiation. Thinner solar cells exhibited smaller efficiency losses than thicker devices; a trend that correlates well with the theoretical prediction using a semi-analytical model.
{"title":"Increased radiation hardness in ultra-thin GaAs single-junction solar cells","authors":"Jacob J. Becker, Ying-Shen Kuo, Yong-Hang Zhang","doi":"10.1109/PVSC.2014.6925281","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925281","url":null,"abstract":"The absorber-thickness dependent, relative efficiency losses for solar cells with a 300 nm, 1000 nm and 2000 nm thick absorber were found to be 20.5%, 26.8% and 28.6%, respectively, after exposure to 1 MeV electron radiation. Thinner solar cells exhibited smaller efficiency losses than thicker devices; a trend that correlates well with the theoretical prediction using a semi-analytical model.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"23 1","pages":"1839-1841"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78723798","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925213
S. Thiyagu, Chen-Chih Hsueh, Chien-Ting Liu, Hong-Jhang Syu, Song-ting Yang, Ching-Fuh Lin
In this work, a simple method of solution process to fabricate high density Silicon nanohole (SiNH) arrays on n-type wafer is experimented. SiNHs exhibit very low reflectance from range of wavelength 300 to 1100 nm irrespective of the angle of incidence, better than Si nanowires. The SiNH arrays have a strong light trapping effect between the nanostructures causes high absorption. We experimentally demonstrate high-efficiency organic-inorganic hybrid solar cells, Si/PEDOT:PSS with silicon nanoholes. Such Si/PEDOT:PSS hybrid solar cells exhibit high Jsc of 36.80 mA/cm2, Voc of 0.52V, FF of 66.50%, and thus power conversion efficiency (PCE) of 12.72%. SiNH arrays produce a large surface-area-to-volume ratio, hence allowing efficient light harvesting and charge collection via the formation of a core-sheath p-n junction.
{"title":"High efficiency hybrid organic/silicon-nanohole heterojunction solar cells","authors":"S. Thiyagu, Chen-Chih Hsueh, Chien-Ting Liu, Hong-Jhang Syu, Song-ting Yang, Ching-Fuh Lin","doi":"10.1109/PVSC.2014.6925213","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925213","url":null,"abstract":"In this work, a simple method of solution process to fabricate high density Silicon nanohole (SiNH) arrays on n-type wafer is experimented. SiNHs exhibit very low reflectance from range of wavelength 300 to 1100 nm irrespective of the angle of incidence, better than Si nanowires. The SiNH arrays have a strong light trapping effect between the nanostructures causes high absorption. We experimentally demonstrate high-efficiency organic-inorganic hybrid solar cells, Si/PEDOT:PSS with silicon nanoholes. Such Si/PEDOT:PSS hybrid solar cells exhibit high Jsc of 36.80 mA/cm2, Voc of 0.52V, FF of 66.50%, and thus power conversion efficiency (PCE) of 12.72%. SiNH arrays produce a large surface-area-to-volume ratio, hence allowing efficient light harvesting and charge collection via the formation of a core-sheath p-n junction.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"14 1","pages":"1553-1555"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75051540","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925018
A. Abbas, G. West, J. Bowers, P. Kamiński, B. Maniscalco, J. Walls, K. Barth, W. Sampath
Although the cadmium chloride treatment is an essential process for high efficiency thin film cadmium telluride photovoltaic devices, the precise mechanisms involved that improve the cadmium telluride layer are not fully understood. The treatment parameters have a narrow window, deviating from these even slightly can be detrimental to cell performance. In this investigation we apply advanced microstructural characterization techniques to study the effects of varying two parameters: the temperature of the substrate during the cadmium chloride treatment and the length of time of the treatment. In both cases, the devices have been deliberately over-treated. The effect of the over-treatment on the microstructure of cadmium telluride solar cells, deposited by close spaced sublimation is investigated and related to cell performance. A range of techniques has been used to observe the changes to the microstructure as well as the chemical and crystallographic changes as a function of treatment parameters. Electrical tests that link the device performance with the microstructural properties of the cells have also been undertaken. Techniques used include Transmission Electron Microscopy (TEM) for sub-grain analysis, EDX for chemical analysis and XPS for composition-depth profiling.
{"title":"Cadmium chloride assisted re-crystallization of CdTe: The effect of annealing over-treatment","authors":"A. Abbas, G. West, J. Bowers, P. Kamiński, B. Maniscalco, J. Walls, K. Barth, W. Sampath","doi":"10.1109/PVSC.2014.6925018","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925018","url":null,"abstract":"Although the cadmium chloride treatment is an essential process for high efficiency thin film cadmium telluride photovoltaic devices, the precise mechanisms involved that improve the cadmium telluride layer are not fully understood. The treatment parameters have a narrow window, deviating from these even slightly can be detrimental to cell performance. In this investigation we apply advanced microstructural characterization techniques to study the effects of varying two parameters: the temperature of the substrate during the cadmium chloride treatment and the length of time of the treatment. In both cases, the devices have been deliberately over-treated. The effect of the over-treatment on the microstructure of cadmium telluride solar cells, deposited by close spaced sublimation is investigated and related to cell performance. A range of techniques has been used to observe the changes to the microstructure as well as the chemical and crystallographic changes as a function of treatment parameters. Electrical tests that link the device performance with the microstructural properties of the cells have also been undertaken. Techniques used include Transmission Electron Microscopy (TEM) for sub-grain analysis, EDX for chemical analysis and XPS for composition-depth profiling.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"33 1","pages":"0701-0706"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75096568","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925181
Mohit Chhabra, F. Barnes
This paper is a continuation of the work conducted in Chhabra, M., Barnes, F., “Robust Current Controller Design using Mu-Synthesis for Grid-Connected Three Phase Inverter” [1]. High penetration of distributed photovoltaic generation on a distribution system can present several challenges and opportunities for utilities. Voltage sags and swells cannot always be compensated for by slowly responding utility equipment, resulting in degradation in power quality. Voltage variations are commonly caused by rapidly varying solar irradiance, and/or variations in the load. In this paper a robust current controller based solar-inverter system is used for voltage regulation at a substation. Conventional inverter current controllers based on proportional-integral (PI) control may not always offer the superior tracking performance, and harmonic rejection ability of robust controllers. We use the repetitive control strategy, in tandem with a mu-synthesis based controller, to attain optimal sinusoidal reference tracking and harmonic rejection. Musynthesis based control is chosen to attain optimal reference tracking in the presence of plant uncertainties. By applying the mu-synthesis principle, a feedback controller that simultaneously achieves robust stability and robust tracking performance is obtained. To test the proposed inverter current controller, the inverter is interconnected to a 500kW solar system model and operated in volt-var control mode. Ten such 500kW solar-inverter systems are paralleled and interconnected to a substation. The substation is modeled with multiple loads, tap changing transformers, and a 70MVar variable capacitor bank. Simulation performance is compared to an H∞ based optimal current controller, and a PI based current controller.
{"title":"Robust Current Controller based solar-inverter system used for voltage regulation at a substation","authors":"Mohit Chhabra, F. Barnes","doi":"10.1109/PVSC.2014.6925181","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925181","url":null,"abstract":"This paper is a continuation of the work conducted in Chhabra, M., Barnes, F., “Robust Current Controller Design using Mu-Synthesis for Grid-Connected Three Phase Inverter” [1]. High penetration of distributed photovoltaic generation on a distribution system can present several challenges and opportunities for utilities. Voltage sags and swells cannot always be compensated for by slowly responding utility equipment, resulting in degradation in power quality. Voltage variations are commonly caused by rapidly varying solar irradiance, and/or variations in the load. In this paper a robust current controller based solar-inverter system is used for voltage regulation at a substation. Conventional inverter current controllers based on proportional-integral (PI) control may not always offer the superior tracking performance, and harmonic rejection ability of robust controllers. We use the repetitive control strategy, in tandem with a mu-synthesis based controller, to attain optimal sinusoidal reference tracking and harmonic rejection. Musynthesis based control is chosen to attain optimal reference tracking in the presence of plant uncertainties. By applying the mu-synthesis principle, a feedback controller that simultaneously achieves robust stability and robust tracking performance is obtained. To test the proposed inverter current controller, the inverter is interconnected to a 500kW solar system model and operated in volt-var control mode. Ten such 500kW solar-inverter systems are paralleled and interconnected to a substation. The substation is modeled with multiple loads, tap changing transformers, and a 70MVar variable capacitor bank. Simulation performance is compared to an H∞ based optimal current controller, and a PI based current controller.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"65 1","pages":"1407-1412"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76510824","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 : 2014-06-08DOI: 10.1109/PVSC.2014.6925324
Chien-Yi Peng, T. Dhakal, Amin Emrani, Susan S. Lu, C. Westgate
Cu2ZnSnS4 (CZTS) thin film solar cells have attracted scientific and economic interest in the last decade. In this study, accelerated thermal cycling and damp heat tests are used to examine the stability of CZTS thin film solar cells, which are coated with two TCO materials. From the results, the CZTS solar cells with ZnO and ITO perform better durability than the one with ZnO and AZO under the accelerated thermal cycling test. The result also indicates that the ZnO and AZO deposited by using atomic layer deposition (ALD) technique does not improve the stability for CZTS solar cells comparing to the sputtering technique. In the damp heat experiment, the results show that the bare ITO thin films and AZO thin films deposited by the ALD technique have a good durability with regard to the moisture ingress. The AZO thin films deposited by RF sputtering without annealing have a worse performance with regard to electrical properties after the damp heat test. However, the cells with an ITO layer do not sustain a good performance after the damp heat test, which could be attributed smaller thickness of the ITO thin films. Although the AZO thin films using the ALD technique have better durability than the ones using the RF sputtering, the cells coated with the ZnO and AZO by the ALD technique are not much better than the cells coated with the ZnO and AZO by the RF sputtering.
{"title":"Stability of CZTS thin film solar cells upon accelerated thermal cycling and damp heat exposure","authors":"Chien-Yi Peng, T. Dhakal, Amin Emrani, Susan S. Lu, C. Westgate","doi":"10.1109/PVSC.2014.6925324","DOIUrl":"https://doi.org/10.1109/PVSC.2014.6925324","url":null,"abstract":"Cu2ZnSnS4 (CZTS) thin film solar cells have attracted scientific and economic interest in the last decade. In this study, accelerated thermal cycling and damp heat tests are used to examine the stability of CZTS thin film solar cells, which are coated with two TCO materials. From the results, the CZTS solar cells with ZnO and ITO perform better durability than the one with ZnO and AZO under the accelerated thermal cycling test. The result also indicates that the ZnO and AZO deposited by using atomic layer deposition (ALD) technique does not improve the stability for CZTS solar cells comparing to the sputtering technique. In the damp heat experiment, the results show that the bare ITO thin films and AZO thin films deposited by the ALD technique have a good durability with regard to the moisture ingress. The AZO thin films deposited by RF sputtering without annealing have a worse performance with regard to electrical properties after the damp heat test. However, the cells with an ITO layer do not sustain a good performance after the damp heat test, which could be attributed smaller thickness of the ITO thin films. Although the AZO thin films using the ALD technique have better durability than the ones using the RF sputtering, the cells coated with the ZnO and AZO by the ALD technique are not much better than the cells coated with the ZnO and AZO by the RF sputtering.","PeriodicalId":6649,"journal":{"name":"2014 IEEE 40th Photovoltaic Specialist Conference (PVSC)","volume":"51 1","pages":"2022-2026"},"PeriodicalIF":0.0,"publicationDate":"2014-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76575307","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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