Dávid Krisztián, F. Korsós, Ilias Saegh, G. Paráda, Martin Kovács, Zita Verdon, Csaba Jobbágy, P. Tüttö, Xueqian Dong, Hao Deng, Shasha Wang, Xiaobo Chen
In the manufacturing of modern solar cells, the early-phase quality inspection is crucial to detect harmful impurities and to reduce production waste. Thus, the charge-carrier lifetime measurement is beneficial before slicing the silicon ingot into wafers. Optimization of the widely used eddy-current detected photoconductance decay (e-PCD) technique for lifetime measurements is necessary to keep the pace with the new challenges appearing in photovoltaics. We investigated the dependence of the accuracy of the measurable carrier lifetime on the excitation laser parameters in the entire relevant carrier lifetime range. The complex behaviour of surface-recombination phenomena and its time evolution is studied by computer simulation. We optimized the components and parameters of the measurement setup and found that a 1064 nm laser is rather optimal compared to the 980 nm laser used previously. Using a longer wavelength laser source with elevated photon flux results in an improved accuracy of carrier lifetime recorded at Δn = 1015 cm−3 excess carrier concentration. A convincing similarity is found by comparing results from as-sliced and passivated surfaces. The optimized laser e-PCD method was compared to the flash-lamp based PCD method (known as QSSPC). Results agree very well for longer carrier lifetimes for which both systems evaluates the PCD curves in transient mode. However, for lower carrier lifetimes the universal transient mode operation of the e-PCD method is advantageous in terms of consistency.
{"title":"Improved accuracy of eddy-current sensor based carrier lifetime measurement using laser excitation","authors":"Dávid Krisztián, F. Korsós, Ilias Saegh, G. Paráda, Martin Kovács, Zita Verdon, Csaba Jobbágy, P. Tüttö, Xueqian Dong, Hao Deng, Shasha Wang, Xiaobo Chen","doi":"10.1051/epjpv/2021014","DOIUrl":"https://doi.org/10.1051/epjpv/2021014","url":null,"abstract":"In the manufacturing of modern solar cells, the early-phase quality inspection is crucial to detect harmful impurities and to reduce production waste. Thus, the charge-carrier lifetime measurement is beneficial before slicing the silicon ingot into wafers. Optimization of the widely used eddy-current detected photoconductance decay (e-PCD) technique for lifetime measurements is necessary to keep the pace with the new challenges appearing in photovoltaics. We investigated the dependence of the accuracy of the measurable carrier lifetime on the excitation laser parameters in the entire relevant carrier lifetime range. The complex behaviour of surface-recombination phenomena and its time evolution is studied by computer simulation. We optimized the components and parameters of the measurement setup and found that a 1064 nm laser is rather optimal compared to the 980 nm laser used previously. Using a longer wavelength laser source with elevated photon flux results in an improved accuracy of carrier lifetime recorded at Δn = 1015 cm−3 excess carrier concentration. A convincing similarity is found by comparing results from as-sliced and passivated surfaces. The optimized laser e-PCD method was compared to the flash-lamp based PCD method (known as QSSPC). Results agree very well for longer carrier lifetimes for which both systems evaluates the PCD curves in transient mode. However, for lower carrier lifetimes the universal transient mode operation of the e-PCD method is advantageous in terms of consistency.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57827913","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 : 2021-10-27DOI: 10.20944/preprints202110.0401.v1
Faisal Saeed, Haider Ali Tauqeer, H. Gelani, Muhammad Hassan Yousuf
Partial shading on solar photovoltaic (PV) arrays is a prevalent problem in photovoltaic systems that impair the performance of PV modules and is responsible for reduced power output as compared to that in standard irradiance conditions thereby resulting in the appearance of multiple maximas on panel output power characteristics. These maxims contribute to mismatch power losses among PV modules. The mismatch losses depend on shading characteristics together with different interconnected configuration schemes of PV modules. The research presents a comparative analysis of partial shading effects on a 4 x4 PV array system connected in series(S), parallel (P), serries-parallel (SP),total-cross-tied (TCT),central-cross-tied(CCT),bridge-linked(BL),bridge-linked total cross-tied (BLTCT) ,honey-comb(HC), honey-comb total-cross-tied (HCTCT) and ladder (LD) configurations using MATLAB/Simulink. The PV module SPR-X20-250-BLK was used for modeling and simulation analysis. Each module is comprised of 72 number of PV cells and a combination of 16 PV modules was employed for the contextual analysis. Accurate mathematical modeling for the HCTCT configuration under partial shading conditions (PSCs) is provided for the first time and is verified from the simulation. The different configuration schemes were investigated under short-narrow,short-wide,long-narrow,long-wide, diagonal, entire row distribution, and entire column distribution partial shading condition patterns with mathematical implementation and simulation of passing clouds. The performance of array configurations is compared in terms of maximum power generated ), mismatch power loss (∆), relative power loss ) and the fill factor (FF). It was inferred that on average, TCT configuration yielded maximum power generation under all shading patterns among all PV modules interconnection configurations with minimum mismatch power losses followed by hybrid and conventional PV array configurations respectively.
{"title":"Numerical Modeling, Simulation and Evaluation of Conventional and Hybrid Photovoltaic Modules Interconnection Configurations under Partial Shading Conditions","authors":"Faisal Saeed, Haider Ali Tauqeer, H. Gelani, Muhammad Hassan Yousuf","doi":"10.20944/preprints202110.0401.v1","DOIUrl":"https://doi.org/10.20944/preprints202110.0401.v1","url":null,"abstract":"Partial shading on solar photovoltaic (PV) arrays is a prevalent problem in photovoltaic systems that impair the performance of PV modules and is responsible for reduced power output as compared to that in standard irradiance conditions thereby resulting in the appearance of multiple maximas on panel output power characteristics. These maxims contribute to mismatch power losses among PV modules. The mismatch losses depend on shading characteristics together with different interconnected configuration schemes of PV modules. The research presents a comparative analysis of partial shading effects on a 4 x4 PV array system connected in series(S), parallel (P), serries-parallel (SP),total-cross-tied (TCT),central-cross-tied(CCT),bridge-linked(BL),bridge-linked total cross-tied (BLTCT) ,honey-comb(HC), honey-comb total-cross-tied (HCTCT) and ladder (LD) configurations using MATLAB/Simulink. The PV module SPR-X20-250-BLK was used for modeling and simulation analysis. Each module is comprised of 72 number of PV cells and a combination of 16 PV modules was employed for the contextual analysis. Accurate mathematical modeling for the HCTCT configuration under partial shading conditions (PSCs) is provided for the first time and is verified from the simulation. The different configuration schemes were investigated under short-narrow,short-wide,long-narrow,long-wide, diagonal, entire row distribution, and entire column distribution partial shading condition patterns with mathematical implementation and simulation of passing clouds. The performance of array configurations is compared in terms of maximum power generated ), mismatch power loss (∆), relative power loss ) and the fill factor (FF). It was inferred that on average, TCT configuration yielded maximum power generation under all shading patterns among all PV modules interconnection configurations with minimum mismatch power losses followed by hybrid and conventional PV array configurations respectively.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2021-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46208273","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 large-scale deployment of photovoltaics (PV) is a central pillar in decarbonizing energy systems and reaching climate goals. Although PV is inherently associated to environmental awareness, it is not immune to reputational risks nor exempt of a responsibility for transparency and sustainability leadership. So far, advances in the PV industry have mainly been shaped by cost-reduction targets. We identified in previous works 16 topics where the PV sector comes short in addressing the United Nations Sustainable Development Goal 12 (SDG 12) “Ensure sustainable consumption and production patterns”. In this paper, practical approaches to address each of these sustainability gaps are proposed. The best-practices identified cover all aspects of sustainability as defined by SDG 12–from resource use and hazardous substances through corporate reporting and risk assessment to due diligence and waste management. Insights on methodological needs to improve sustainability assessment and accounting in PV are also provided. The compiled list of actions needed, although not intended to be exhaustive, constitutes a starting point for stakeholders to raise their ambitions and achieve more sustainability in PV value chains.
{"title":"Sustainability strategies for PV: framework, status and needs","authors":"Estelle Gervais, Sina Herceg, S. Nold, K. Weiß","doi":"10.1051/epjpv/2021005","DOIUrl":"https://doi.org/10.1051/epjpv/2021005","url":null,"abstract":"The large-scale deployment of photovoltaics (PV) is a central pillar in decarbonizing energy systems and reaching climate goals. Although PV is inherently associated to environmental awareness, it is not immune to reputational risks nor exempt of a responsibility for transparency and sustainability leadership. So far, advances in the PV industry have mainly been shaped by cost-reduction targets. We identified in previous works 16 topics where the PV sector comes short in addressing the United Nations Sustainable Development Goal 12 (SDG 12) “Ensure sustainable consumption and production patterns”. In this paper, practical approaches to address each of these sustainability gaps are proposed. The best-practices identified cover all aspects of sustainability as defined by SDG 12–from resource use and hazardous substances through corporate reporting and risk assessment to due diligence and waste management. Insights on methodological needs to improve sustainability assessment and accounting in PV are also provided. The compiled list of actions needed, although not intended to be exhaustive, constitutes a starting point for stakeholders to raise their ambitions and achieve more sustainability in PV value chains.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57827757","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}
High conductivity and transparency of the electron-transporting layer (ETL) is essential to achieve high efficiency perovskite solar cells (PvSCs). Generally, titanium dioxide (TiO2) has been extensively utilized as an ETL in PvSCs. Both surface roughness and uniformity of the compact-TiO2 (C-TiO2) can influence the efficiency of the PvSC. This work investigates the optimization of the direct current (DC) sputtering power and the ratio of argon (Ar) to oxygen (O2) plasma to achieve high quality ETL films. The effect of changing the DC sputtering power on the C-TiO2 films and subsequently on the overall efficiency was studied. The electrical and optical properties of the C-TiO2 layer were characterized for various DC powers and different ratios of Ar to O2 plasma. It was found that the optimum preparation conditions for the C-TiO2 films were obtained when the DC power was set at 200 W and a flow rate of 6 sccm Ar and 12 sccm O2. A power conversion efficiency (PCE) of 15.3% in forward sweep and 16.7% in reverse sweep were achieved under sunlight simulator of 100 mW/cm2. These results indicate that significant improvement in the efficiency can be achieved, by optimizing the C-TiO2 layer.
{"title":"High efficiency perovskite solar cells using DC sputtered compact TiO2 electron transport layer","authors":"Ahmed Hayali, M. Alkaisi","doi":"10.1051/epjpv/2021008","DOIUrl":"https://doi.org/10.1051/epjpv/2021008","url":null,"abstract":"High conductivity and transparency of the electron-transporting layer (ETL) is essential to achieve high efficiency perovskite solar cells (PvSCs). Generally, titanium dioxide (TiO2) has been extensively utilized as an ETL in PvSCs. Both surface roughness and uniformity of the compact-TiO2 (C-TiO2) can influence the efficiency of the PvSC. This work investigates the optimization of the direct current (DC) sputtering power and the ratio of argon (Ar) to oxygen (O2) plasma to achieve high quality ETL films. The effect of changing the DC sputtering power on the C-TiO2 films and subsequently on the overall efficiency was studied. The electrical and optical properties of the C-TiO2 layer were characterized for various DC powers and different ratios of Ar to O2 plasma. It was found that the optimum preparation conditions for the C-TiO2 films were obtained when the DC power was set at 200 W and a flow rate of 6 sccm Ar and 12 sccm O2. A power conversion efficiency (PCE) of 15.3% in forward sweep and 16.7% in reverse sweep were achieved under sunlight simulator of 100 mW/cm2. These results indicate that significant improvement in the efficiency can be achieved, by optimizing the C-TiO2 layer.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57827826","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}
M. Rienäcker, Y. Larionova, J. Krügener, S. Wolter, R. Brendel, R. Peibst
Polysilicon-on-oxide (POLO) passivating contacts and interdigitated back-contact (IBC) cell technologies have recently attracted a lot of interest as candidates for the implementation in the next generation of solar cells. An IBC cell with POLO junctions for both polarities − a POLO2-IBC cell − has to electrically isolate the highly defective p+ and n+ poly-Si regions on the rear side of the cell to avoid parasitic recombination. Inserting an initially undoped, intrinsic (i) region between the p+ and n+ poly-Si regions was demonstrated to successfully prevent the parasitic recombination in the transition region of ISFH's 26.1%-efficient POLO2-IBC cell. In order to further improve the conversion efficiency towards 27%, we apply hydrogen-donating dielectric layer stacks to the p+-(i)-n+ POLO interdigitating rear side to enhance the passivation quality of the POLO junctions. We indeed show a significant improvement of POLO junctions on symmetrical full-area homogenously doped reference samples, but when we apply a hydrogen-donating layer stack on the p+-(i)-n+ POLO interdigitating rear side, we observe a strong degradation in the performance of the POLO2-IBC cell. We attribute this to the formation of a conductive channel between the p+ and n+ poly-Si regions due to the strong negative charge density of the hydrogen-donating layer stack.
{"title":"Rear side dielectrics on interdigitating p+-(i)-n+ back-contact solar cells − hydrogenation vs. charge effects","authors":"M. Rienäcker, Y. Larionova, J. Krügener, S. Wolter, R. Brendel, R. Peibst","doi":"10.1051/epjpv/2021007","DOIUrl":"https://doi.org/10.1051/epjpv/2021007","url":null,"abstract":"Polysilicon-on-oxide (POLO) passivating contacts and interdigitated back-contact (IBC) cell technologies have recently attracted a lot of interest as candidates for the implementation in the next generation of solar cells. An IBC cell with POLO junctions for both polarities − a POLO2-IBC cell − has to electrically isolate the highly defective p+ and n+ poly-Si regions on the rear side of the cell to avoid parasitic recombination. Inserting an initially undoped, intrinsic (i) region between the p+ and n+ poly-Si regions was demonstrated to successfully prevent the parasitic recombination in the transition region of ISFH's 26.1%-efficient POLO2-IBC cell. In order to further improve the conversion efficiency towards 27%, we apply hydrogen-donating dielectric layer stacks to the p+-(i)-n+ POLO interdigitating rear side to enhance the passivation quality of the POLO junctions. We indeed show a significant improvement of POLO junctions on symmetrical full-area homogenously doped reference samples, but when we apply a hydrogen-donating layer stack on the p+-(i)-n+ POLO interdigitating rear side, we observe a strong degradation in the performance of the POLO2-IBC cell. We attribute this to the formation of a conductive channel between the p+ and n+ poly-Si regions due to the strong negative charge density of the hydrogen-donating layer stack.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57827782","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}
C. Chevallier, S. Bose, Sidi Ould Saad Hamady, N. Fressengeas
Numerical simulations of AZO/Zn1−xGexO/Cu2O solar cell are performed in order to model for the first time the impact of the germanium composition of the ZnGeO buffer layer on the photovoltaic conversion efficiency. The physical parameters of the model are chosen with special care to match literature experimental measurements or are interpolated using the values from binary metal oxides in the case of the new Zn1−xGexO compound. The solar cell model accuracy is then confirmed thanks to the comparison of its predictions with measurements from the literature that were done on experimental devices obtained by thermal oxidation. This validation of the AZO/Zn1−xGexO/Cu2O model then allows to study the impact of the use of the low cost, environmental friendly and industrially compatible spray pyrolysis process on the solar cell efficiency. To that aim, the Cu2O absorber layer parameters are adjusted to typical values obtained by the spray pyrolysis process by selecting state of the art experimental data. The analysis of the impact of the absorber layer thickness, the carrier mobility, the defect and doping concentration on the solar cell performances allows to draw guidelines for ZnGeO/Cu2O thin film photovoltaic device realization through spray pyrolysis.
{"title":"Numerical investigations of the impact of buffer germanium composition and low cost fabrication of Cu2O on AZO/ZnGeO/Cu2O solar cell performances","authors":"C. Chevallier, S. Bose, Sidi Ould Saad Hamady, N. Fressengeas","doi":"10.1051/epjpv/2021003","DOIUrl":"https://doi.org/10.1051/epjpv/2021003","url":null,"abstract":"Numerical simulations of AZO/Zn1−xGexO/Cu2O solar cell are performed in order to model for the first time the impact of the germanium composition of the ZnGeO buffer layer on the photovoltaic conversion efficiency. The physical parameters of the model are chosen with special care to match literature experimental measurements or are interpolated using the values from binary metal oxides in the case of the new Zn1−xGexO compound. The solar cell model accuracy is then confirmed thanks to the comparison of its predictions with measurements from the literature that were done on experimental devices obtained by thermal oxidation. This validation of the AZO/Zn1−xGexO/Cu2O model then allows to study the impact of the use of the low cost, environmental friendly and industrially compatible spray pyrolysis process on the solar cell efficiency. To that aim, the Cu2O absorber layer parameters are adjusted to typical values obtained by the spray pyrolysis process by selecting state of the art experimental data. The analysis of the impact of the absorber layer thickness, the carrier mobility, the defect and doping concentration on the solar cell performances allows to draw guidelines for ZnGeO/Cu2O thin film photovoltaic device realization through spray pyrolysis.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57827708","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}
For the past 10 years, photovoltaic electricity generation has been the fastest-growing power generation source worldwide. It took almost six decades to achieve 100 GW of solar energy capacity in 2012, but the 1 TW barrier is likely to be broken during 2022. Despite the ongoing COVID-19 pandemic, the overall investments in solar energy have increased by 12% to USD 148.6 billion (EUR 125 billion). In 2020, more than 135 GW of new solar photovoltaic electricity generation capacity was installed. The recovery of China, the continuous growths in Europe and the USA as well as new emerging markets were the main drivers. The number of countries installing more than 1 GW annually has increased to 18 in 2020. The continuation of price reductions in the battery storage sector has again resulted in a growing market for local battery storage systems in solar farms as well as decentralised photovoltaic electricity generation systems. Apart from classic electricity use, renewable electricity for the generation of green hydrogen will become more and more important in the future.
{"title":"Snapshot of photovoltaics − March 2021","authors":"A. Jäger-Waldau","doi":"10.1051/EPJPV/2021002","DOIUrl":"https://doi.org/10.1051/EPJPV/2021002","url":null,"abstract":"For the past 10 years, photovoltaic electricity generation has been the fastest-growing power generation source worldwide. It took almost six decades to achieve 100 GW of solar energy capacity in 2012, but the 1 TW barrier is likely to be broken during 2022. Despite the ongoing COVID-19 pandemic, the overall investments in solar energy have increased by 12% to USD 148.6 billion (EUR 125 billion). In 2020, more than 135 GW of new solar photovoltaic electricity generation capacity was installed. The recovery of China, the continuous growths in Europe and the USA as well as new emerging markets were the main drivers. The number of countries installing more than 1 GW annually has increased to 18 in 2020. The continuation of price reductions in the battery storage sector has again resulted in a growing market for local battery storage systems in solar farms as well as decentralised photovoltaic electricity generation systems. Apart from classic electricity use, renewable electricity for the generation of green hydrogen will become more and more important in the future.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":"9 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57827699","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}
Inorganic–organic hybrid perovskites offer wide optical absorption, long charge carrier diffusion length, and high optical-to-electrical conversion, enabling more than 25% efficiency of single-junction perovskite solar cells. All-perovskite four-terminal (4T) tandem solar cells have gained great attention because of solution-processability and potentially high efficiency without a need for current-matching between subcells. To make the best use of a tandem architecture, the subcell bandgaps and thicknesses must be optimized. This study presents a drift-diffusion simulation model to find optimum device parameters for a 4T tandem cell exceeding 33% of efficiency. Optimized subcell bandgaps and thicknesses, contact workfunctions, charge transport layer doping and perovskite surface modification are investigated for all-perovskite 4T tandem solar cells. Also, using real material and device parameters, the impact of bulk and interface traps is investigated. It is observed that, despite high recombination losses, the 4T device can achieve very high efficiencies for a broad range of bandgap combinations. We obtained the best efficiency for top and bottom cell bandgaps close to 1.55 eV and 0.9 eV, respectively. The optimum thickness of the top and bottom cells are found to be about 250 nm and 450 nm, respectively. Furthermore, we investigated that doping in the hole transport layers in both the subcells can significantly improve tandem cell efficiency. The present study will provide the experimentalists an optimum device with optimized bandgaps, thicknesses, contact workfunctions, perovskite surface modification and doping in subcells, enabling high-efficiency all-perovskite 4T tandem solar cells.
{"title":"Device simulation of all-perovskite four-terminal tandem solar cells: towards 33% efficiency","authors":"Ajay Singh, A. Gagliardi","doi":"10.1051/epjpv/2021004","DOIUrl":"https://doi.org/10.1051/epjpv/2021004","url":null,"abstract":"Inorganic–organic hybrid perovskites offer wide optical absorption, long charge carrier diffusion length, and high optical-to-electrical conversion, enabling more than 25% efficiency of single-junction perovskite solar cells. All-perovskite four-terminal (4T) tandem solar cells have gained great attention because of solution-processability and potentially high efficiency without a need for current-matching between subcells. To make the best use of a tandem architecture, the subcell bandgaps and thicknesses must be optimized. This study presents a drift-diffusion simulation model to find optimum device parameters for a 4T tandem cell exceeding 33% of efficiency. Optimized subcell bandgaps and thicknesses, contact workfunctions, charge transport layer doping and perovskite surface modification are investigated for all-perovskite 4T tandem solar cells. Also, using real material and device parameters, the impact of bulk and interface traps is investigated. It is observed that, despite high recombination losses, the 4T device can achieve very high efficiencies for a broad range of bandgap combinations. We obtained the best efficiency for top and bottom cell bandgaps close to 1.55 eV and 0.9 eV, respectively. The optimum thickness of the top and bottom cells are found to be about 250 nm and 450 nm, respectively. Furthermore, we investigated that doping in the hole transport layers in both the subcells can significantly improve tandem cell efficiency. The present study will provide the experimentalists an optimum device with optimized bandgaps, thicknesses, contact workfunctions, perovskite surface modification and doping in subcells, enabling high-efficiency all-perovskite 4T tandem solar cells.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57827713","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. Torres-Jaramillo, R. Bernal-Correa, A. Morales-Acevedo
Optimizing any tandem solar cells design before making them experimentally is an important way of reducing development costs. Hence, in this work, we have used a complete analytical model that includes the important effects in the depletion regions of the III-V compound cells in order to simulate the behavior of two and four-terminal InGaP/GaAs//Si tandem solar cells for optimizing them. The design optimization procedure is described first, and then it is shown that the expected practical efficiencies at 1 sun (AM1.5 spectrum) for both two and four-terminal tandem cells can be around 40% when the appropriate thickness for each layer is used. The optimized design for both structures includes a double MgF2/ZnS anti-reflection layer (ARC). The results show that the optimum thicknesses are 130 (MgF2) and 60 nm (ZnS), respectively, while the optimum InGaP thickness is 220 nm and GaAs optimum thickness is 1800 nm for the four-terminal tandem on a HIT silicon solar cell (with total tandem efficiency around 39.8%). These results can be compared with the recent record experimental efficiency around 35.9% for this kind of solar cells. Therefore, triple junction InGaP/GaAs//Silicon tandem solar cells continue being very attractive for further development, using high efficiency HIT silicon cell as the bottom sub-cell.
{"title":"Improved design of InGaP/GaAs//Si tandem solar cells","authors":"S. Torres-Jaramillo, R. Bernal-Correa, A. Morales-Acevedo","doi":"10.1051/EPJPV/2021001","DOIUrl":"https://doi.org/10.1051/EPJPV/2021001","url":null,"abstract":"Optimizing any tandem solar cells design before making them experimentally is an important way of reducing development costs. Hence, in this work, we have used a complete analytical model that includes the important effects in the depletion regions of the III-V compound cells in order to simulate the behavior of two and four-terminal InGaP/GaAs//Si tandem solar cells for optimizing them. The design optimization procedure is described first, and then it is shown that the expected practical efficiencies at 1 sun (AM1.5 spectrum) for both two and four-terminal tandem cells can be around 40% when the appropriate thickness for each layer is used. The optimized design for both structures includes a double MgF2/ZnS anti-reflection layer (ARC). The results show that the optimum thicknesses are 130 (MgF2) and 60 nm (ZnS), respectively, while the optimum InGaP thickness is 220 nm and GaAs optimum thickness is 1800 nm for the four-terminal tandem on a HIT silicon solar cell (with total tandem efficiency around 39.8%). These results can be compared with the recent record experimental efficiency around 35.9% for this kind of solar cells. Therefore, triple junction InGaP/GaAs//Silicon tandem solar cells continue being very attractive for further development, using high efficiency HIT silicon cell as the bottom sub-cell.","PeriodicalId":42768,"journal":{"name":"EPJ Photovoltaics","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57827691","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}
J. Markert, Sandra Kotterer, D. Mansour, D. Philipp, P. Gebhardt
Backsheet degradation is a known reliability issue affecting field-exposed photovoltaic (PV) modules power plants. In this work, we present lessons learned during the last three years, examining modules from 26 power plants in the TestLab PV Modules at Fraunhofer ISE. The basis is a description of the currently observed backsheets and associated degradation features as for example backsheet chalking, cracks in different layers and chemical changes in composition. Furthermore, we lay out analytical methods for initial and more detailed analysis of the failures and module materials. For example, a method designated as “flashlight test” has been found to provide a quick and straightforward method to identify damaged polypropylene (PP) layers within backsheets. Furthermore, scanning acoustic microscopy (SAM) and a comparison of different variants of FTIR spectroscopy are presented.
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