Silicon heterojunction (SHJ) solar cells have recently reached power conversion efficiencies above 25% with various device architectures and with industrial size (>200 cm 2 ) wafers. Yet, for an accurate assessment of the efficiency potential and further development of the technology, the identification of high-performing device configurations, and their detailed analysis is still vital. In this work, we first present an overview of our lab-scale (4 cm 2 ) front-junction cells based on n-type wafers with a 24.44% certified efficiency. We report on the key improvements compared with our previously reported devices (i.e., thinner front-side silicon layers and low refractive index rear reflector). Then, we present a detailed power loss analysis, showing that parasitic absorption in the front layer-stack remains a major source of loss despite the recent improvements. Accordingly, we investigate next approaches to circumvent this loss, such as localization of the highly absorbing front layers and switching to a rear-junction architecture. Using numerical calculations, we show that the front-junction configuration can benefit from an efficiency gain of 0.3% abs with contact localization if considerably low contact resistivities (<20>2 ) are realized for the p-type contact. Even larger gain in efficiency can be achieved by simultaneously switching to a rear-junction architecture and localizing the n-type contact with contact resistivities that are relatively accessible with the current state of the art (up to 0.7% abs gain for <20>2 ). Finally, we propose a simple fabrication method for contact localization using shadow masks during depositions of the front-side layers and demonstrate proof-of-concept cells with localized contacts.
{"title":"Loss Analysis of a 24.4%-Efficient Front-Junction Silicon Heterojunction Solar Cell and Opportunity for Localized Contacts","authors":"Mathieu Boccard;Luca Antognini;Jean Cattin;Julie Dréon;Wenjie Lin;Vincent Paratte;Deniz Turkay;Christophe Ballif","doi":"10.1109/JPHOTOV.2023.3291050","DOIUrl":"https://doi.org/10.1109/JPHOTOV.2023.3291050","url":null,"abstract":"Silicon heterojunction (SHJ) solar cells have recently reached power conversion efficiencies above 25% with various device architectures and with industrial size (>200 cm\u0000<sup>2</sup>\u0000) wafers. Yet, for an accurate assessment of the efficiency potential and further development of the technology, the identification of high-performing device configurations, and their detailed analysis is still vital. In this work, we first present an overview of our lab-scale (4 cm\u0000<sup>2</sup>\u0000) front-junction cells based on n-type wafers with a 24.44% certified efficiency. We report on the key improvements compared with our previously reported devices (i.e., thinner front-side silicon layers and low refractive index rear reflector). Then, we present a detailed power loss analysis, showing that parasitic absorption in the front layer-stack remains a major source of loss despite the recent improvements. Accordingly, we investigate next approaches to circumvent this loss, such as localization of the highly absorbing front layers and switching to a rear-junction architecture. Using numerical calculations, we show that the front-junction configuration can benefit from an efficiency gain of 0.3%\u0000<sub>abs</sub>\u0000 with contact localization if considerably low contact resistivities (<20>2</sup>\u0000) are realized for the p-type contact. Even larger gain in efficiency can be achieved by simultaneously switching to a rear-junction architecture and localizing the n-type contact with contact resistivities that are relatively accessible with the current state of the art (up to 0.7%\u0000<sub>abs</sub>\u0000 gain for <20>2</sup>\u0000). Finally, we propose a simple fabrication method for contact localization using shadow masks during depositions of the front-side layers and demonstrate proof-of-concept cells with localized contacts.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"13 5","pages":"663-671"},"PeriodicalIF":3.0,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3514341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-13DOI: 10.1109/JPHOTOV.2023.3291453
Axel Herguth;Joshua Kamphues
Recombination of excess charge carriers in semiconductors occurring in emitter layers or at the interface to dielectric layers is typically assessed via injection-dependent lifetime measurements exploiting its specific injection dependence. A key assumption is that recombination in the bulk is negligible. Within this contribution it is shown in theory and experiment how neglected recombination in the bulk and its specific injection dependence can interfere with the correct assessment of surface passivation quality, in particular in the context of studies on lifetime degradation phenomena. The role of substrate doping, lifetime limitation by bulk defects and their specific properties is discussed.
{"title":"On the Impact of Bulk Lifetime on the Quantification of Recombination at the Surface of Semiconductors","authors":"Axel Herguth;Joshua Kamphues","doi":"10.1109/JPHOTOV.2023.3291453","DOIUrl":"https://doi.org/10.1109/JPHOTOV.2023.3291453","url":null,"abstract":"Recombination of excess charge carriers in semiconductors occurring in emitter layers or at the interface to dielectric layers is typically assessed via injection-dependent lifetime measurements exploiting its specific injection dependence. A key assumption is that recombination in the bulk is negligible. Within this contribution it is shown in theory and experiment how neglected recombination in the bulk and its specific injection dependence can interfere with the correct assessment of surface passivation quality, in particular in the context of studies on lifetime degradation phenomena. The role of substrate doping, lifetime limitation by bulk defects and their specific properties is discussed.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"13 5","pages":"672-681"},"PeriodicalIF":3.0,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3517782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-11DOI: 10.1109/JPHOTOV.2023.3291048
Edris Khorani;Christoph A. Messmer;Sophie L. Pain;Tim Niewelt;Brendan F. M. Healy;Ailish Wratten;Marc Walker;Nicholas E. Grant;John D. Murphy
Minimizing electrical losses at metal/silicon interfaces in high-efficiency single-junction silicon solar cells requires the use of carrier-selective passivating contacts. The electronic barrier heights at the insulator/silicon interface are necessary for calculating the probability of quantum tunneling of charge carriers at these interfaces. Thus, precise knowledge of these parameters is crucial for the development of contact schemes. Using a photoemission-based method, we experimentally determine the electronic band offsets of Al 2 O 3 , HfO 2 and SiO 2 layers grown by atomic layer deposition (ALD) on silicon. For Al 2 O 3 /Si, we determine a valence band offset (Δ EV ) and conduction band offset (Δ EC ) of 3.29 ± 0.07 eV and 2.24 ± 0.13 eV, respectively. For HfO 2 /Si, Δ EV and Δ EC are determined as 2.67 ± 0.07 eV and 1.81 ± 0.21 eV, while for SiO 2 /Si, Δ EV and Δ EC are 4.87 ± 0.07 eV and 2.61 ± 0.12 eV, respectively. Using technology computer-aided design simulations, we incorporate our experimental results to estimate the contact resistivity that would be attained at various dielectric layer thicknesses. We find that for achieving the 100 mΩ·cm 2 contact resistivity benchmark, Al 2 O 3 layers should be no thicker than 1.65 nm for a p -type polysilicon-based hole-selective contact, assuming hole tunneling masses taken from the literature. Correspondingly, for HfO 2 and SiO 2 , an upper limit of 1.4 nm is determined as the thickness threshold in order to utilize these ALD-grown layers for contacts in high-performance silicon photovoltaics.
{"title":"Electronic Band Offset Determination of Oxides Grown by Atomic Layer Deposition on Silicon","authors":"Edris Khorani;Christoph A. Messmer;Sophie L. Pain;Tim Niewelt;Brendan F. M. Healy;Ailish Wratten;Marc Walker;Nicholas E. Grant;John D. Murphy","doi":"10.1109/JPHOTOV.2023.3291048","DOIUrl":"https://doi.org/10.1109/JPHOTOV.2023.3291048","url":null,"abstract":"Minimizing electrical losses at metal/silicon interfaces in high-efficiency single-junction silicon solar cells requires the use of carrier-selective passivating contacts. The electronic barrier heights at the insulator/silicon interface are necessary for calculating the probability of quantum tunneling of charge carriers at these interfaces. Thus, precise knowledge of these parameters is crucial for the development of contact schemes. Using a photoemission-based method, we experimentally determine the electronic band offsets of Al\u0000<sub>2</sub>\u0000O\u0000<sub>3</sub>\u0000, HfO\u0000<sub>2</sub>\u0000 and SiO\u0000<sub>2</sub>\u0000 layers grown by atomic layer deposition (ALD) on silicon. For Al\u0000<sub>2</sub>\u0000O\u0000<sub>3</sub>\u0000/Si, we determine a valence band offset (Δ\u0000<italic>E<sub>V</sub></i>\u0000) and conduction band offset (Δ\u0000<italic>E<sub>C</sub></i>\u0000) of 3.29 ± 0.07 eV and 2.24 ± 0.13 eV, respectively. For HfO\u0000<sub>2</sub>\u0000/Si, Δ\u0000<italic>E<sub>V</sub></i>\u0000 and Δ\u0000<italic>E<sub>C</sub></i>\u0000 are determined as 2.67 ± 0.07 eV and 1.81 ± 0.21 eV, while for SiO\u0000<sub>2</sub>\u0000/Si, Δ\u0000<italic>E<sub>V</sub></i>\u0000 and Δ\u0000<italic>E<sub>C</sub></i>\u0000 are 4.87 ± 0.07 eV and 2.61 ± 0.12 eV, respectively. Using technology computer-aided design simulations, we incorporate our experimental results to estimate the contact resistivity that would be attained at various dielectric layer thicknesses. We find that for achieving the 100 mΩ·cm\u0000<sup>2</sup>\u0000 contact resistivity benchmark, Al\u0000<sub>2</sub>\u0000O\u0000<sub>3</sub>\u0000 layers should be no thicker than 1.65 nm for a \u0000<italic>p</i>\u0000-type polysilicon-based hole-selective contact, assuming hole tunneling masses taken from the literature. Correspondingly, for HfO\u0000<sub>2</sub>\u0000 and SiO\u0000<sub>2</sub>\u0000, an upper limit of 1.4 nm is determined as the thickness threshold in order to utilize these ALD-grown layers for contacts in high-performance silicon photovoltaics.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"13 5","pages":"682-690"},"PeriodicalIF":3.0,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3515518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-10DOI: 10.1109/JPHOTOV.2023.3289574
Nabarun Saha;Giuseppe Brunetti;Mario N. Armenise;Aldo Di Carlo;Caterina Ciminelli
Perovskite-based solar cells have observed tremendous growth in the last decade aiming at developing renewable energy sources. The enhancement of the power conversion efficiency (PCE), sustainability, and easing of the fabrication are the main driving forces of the ongoing research activity. In this context, graphene is particularly promising since it not only provides better charge collection but also helps to improve the sustainability and low-temperature fabrication of the perovskite cell. Here, a homojunction MaPbI 3 perovskite solar cell with graphene-TiO 2 nano-composite as the electron transport layer (ETL) has been numerically investigated. The effect of doping concentration on the p and n-doped section in the homojunction-MaPbI 3 has been studied, showing that 10 17 and 10 16 cm −3 doping on the p and n section of MaPbI 3 , respectively, provide the best band alignment with the ETL layer. The optimum thickness ratio of two doped sections (p:n) is found to be 60:40 in %. Moreover, the presence of graphene in the TiO 2 layer improves PCE thanks to enhanced fill factor and saturated current density. A combined effect of all these results in a PCE of 22.71% with a 100 nm thick ETL layer having an optimum graphene concentration of around 1%.
以钙钛矿为基础的太阳能电池在过去十年中取得了巨大的增长，旨在开发可再生能源。提高功率转换效率(PCE)、可持续性和易于制造是目前研究活动的主要推动力。在这种情况下，石墨烯特别有前途，因为它不仅提供更好的电荷收集，而且有助于提高钙钛矿电池的可持续性和低温制造。本文对以石墨烯- tio2纳米复合材料为电子传输层(ETL)的MaPbI3钙钛矿太阳能电池进行了数值研究。研究了掺杂浓度对同结MaPbI3中p和n掺杂部分的影响，结果表明，在MaPbI3的p和n部分分别掺杂1017和1016 cm−3，可以提供与ETL层的最佳能带对准。发现两个掺杂截面的最佳厚度比(p:n)为60:40 in %。此外，由于填充系数和饱和电流密度的增强，二氧化钛层中石墨烯的存在改善了PCE。综上所述，PCE为22.71%，而100 nm厚的ETL层的最佳石墨烯浓度约为1%。
{"title":"Modeling Highly Efficient Homojunction Perovskite Solar Cells With Graphene-TiO2 Nanocomposite as the Electron Transport Layer","authors":"Nabarun Saha;Giuseppe Brunetti;Mario N. Armenise;Aldo Di Carlo;Caterina Ciminelli","doi":"10.1109/JPHOTOV.2023.3289574","DOIUrl":"https://doi.org/10.1109/JPHOTOV.2023.3289574","url":null,"abstract":"Perovskite-based solar cells have observed tremendous growth in the last decade aiming at developing renewable energy sources. The enhancement of the power conversion efficiency (PCE), sustainability, and easing of the fabrication are the main driving forces of the ongoing research activity. In this context, graphene is particularly promising since it not only provides better charge collection but also helps to improve the sustainability and low-temperature fabrication of the perovskite cell. Here, a homojunction MaPbI\u0000<sub>3</sub>\u0000 perovskite solar cell with graphene-TiO\u0000<sub>2</sub>\u0000 nano-composite as the electron transport layer (ETL) has been numerically investigated. The effect of doping concentration on the p and n-doped section in the homojunction-MaPbI\u0000<sub>3</sub>\u0000 has been studied, showing that 10\u0000<sup>17</sup>\u0000 and 10\u0000<sup>16</sup>\u0000 cm\u0000<sup>−3</sup>\u0000 doping on the p and n section of MaPbI\u0000<sub>3</sub>\u0000, respectively, provide the best band alignment with the ETL layer. The optimum thickness ratio of two doped sections (p:n) is found to be 60:40 in %. Moreover, the presence of graphene in the TiO\u0000<sub>2</sub>\u0000 layer improves PCE thanks to enhanced fill factor and saturated current density. A combined effect of all these results in a PCE of 22.71% with a 100 nm thick ETL layer having an optimum graphene concentration of around 1%.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"13 5","pages":"705-710"},"PeriodicalIF":3.0,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/5503869/10234139/10177375.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3490137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-07DOI: 10.1109/JPHOTOV.2023.3289576
Timothy J Silverman;Michael G. Deceglie;Ingrid R. Repins;Tao Zhu;Zhaoning Song;Michael J. Heben;Yanfa Yan;Chengbin Fei;Jinsong Huang;Laura T. Schelhas
Metal halide perovskite photovoltaic modules deployed outdoors and held at their maximum power point show daily, reversible, relative changes of up to 30% in efficiency between morning and afternoon. Predicting energy yield and quantifying reliability will require properly handling such daily performance changes.
{"title":"Daily Performance Changes in Metal Halide Perovskite PV Modules","authors":"Timothy J Silverman;Michael G. Deceglie;Ingrid R. Repins;Tao Zhu;Zhaoning Song;Michael J. Heben;Yanfa Yan;Chengbin Fei;Jinsong Huang;Laura T. Schelhas","doi":"10.1109/JPHOTOV.2023.3289576","DOIUrl":"https://doi.org/10.1109/JPHOTOV.2023.3289576","url":null,"abstract":"Metal halide perovskite photovoltaic modules deployed outdoors and held at their maximum power point show daily, reversible, relative changes of up to 30% in efficiency between morning and afternoon. Predicting energy yield and quantifying reliability will require properly handling such daily performance changes.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"13 5","pages":"740-742"},"PeriodicalIF":3.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3491478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-26DOI: 10.1109/JPHOTOV.2023.3282707
Gérard Daligou;Richard Soref;Anis Attiaoui;Jaker Hossain;Mahmoud R. M. Atalla;Patrick Del Vecchio;Oussama Moutanabbir
Compound semiconductors have been the predominant building blocks for the current midinfrared thermophotovoltaic devices relevant to sub-$2000 ,mathrm{K}$ heat conversion and power beaming. However, the prohibitively high cost associated with these technologies limits their broad adoption. Herein, to alleviate this challenge we introduce an all-group IV midinfrared cell consisting of GeSn alloy directly on a silicon wafer. This emerging class of semiconductors provides strain and composition as degrees of freedom to control the bandgap energy thus covering the entire midinfrared range. The proposed thermophotovoltaic device is composed of a fully relaxed Ge$_{0.83}$Sn$_{0.17}$$p$-$i$-$n$ homojunction corresponding to a bandgap energy of $0.29 ,mathrm{emathrm{V}}$. A theoretical framework is derived to evaluate cell performance under high injection. The black-body radiation absorption is investigated using the generalized transfer matrix method thereby considering the mixed coherent/incoherent layer stacking. Moreover, the intrinsic recombination mechanisms and their importance in a narrow bandgap semiconductor were also taken into account. In this regard, the parabolic band approximation and Fermi's golden rule were combined for an accurate estimation of the radiative recombination rate. Based on these analyses, power conversion efficiencies of up to 9% are predicted for Ge$_{0.83}$Sn$_{0.17}$ thermophotovoltaic cells under black-body radiation at temperatures in the 500–$1500 ,mathrm{K}$ range. A slight improvement in the efficiency is observed under the frontside illumination but vanishes below $800 ,mathrm{K}$, while the use of a backside reflector improves the efficiency across the investigated black-body temperature range. The effects of the heterostructure thickness, surface recombination velocity, and carrier lifetime are also elucidated and discussed.
{"title":"Group IV Mid-Infrared Thermophotovoltaic Cells on Silicon","authors":"Gérard Daligou;Richard Soref;Anis Attiaoui;Jaker Hossain;Mahmoud R. M. Atalla;Patrick Del Vecchio;Oussama Moutanabbir","doi":"10.1109/JPHOTOV.2023.3282707","DOIUrl":"https://doi.org/10.1109/JPHOTOV.2023.3282707","url":null,"abstract":"Compound semiconductors have been the predominant building blocks for the current midinfrared thermophotovoltaic devices relevant to sub-<inline-formula><tex-math notation=\"LaTeX\">$2000 ,mathrm{K}$</tex-math></inline-formula> heat conversion and power beaming. However, the prohibitively high cost associated with these technologies limits their broad adoption. Herein, to alleviate this challenge we introduce an all-group IV midinfrared cell consisting of GeSn alloy directly on a silicon wafer. This emerging class of semiconductors provides strain and composition as degrees of freedom to control the bandgap energy thus covering the entire midinfrared range. The proposed thermophotovoltaic device is composed of a fully relaxed Ge<inline-formula><tex-math notation=\"LaTeX\">$_{0.83}$</tex-math></inline-formula>Sn<inline-formula><tex-math notation=\"LaTeX\">$_{0.17}$</tex-math></inline-formula> <inline-formula><tex-math notation=\"LaTeX\">$p$</tex-math></inline-formula>-<inline-formula><tex-math notation=\"LaTeX\">$i$</tex-math></inline-formula>-<inline-formula><tex-math notation=\"LaTeX\">$n$</tex-math></inline-formula> homojunction corresponding to a bandgap energy of <inline-formula><tex-math notation=\"LaTeX\">$0.29 ,mathrm{emathrm{V}}$</tex-math></inline-formula>. A theoretical framework is derived to evaluate cell performance under high injection. The black-body radiation absorption is investigated using the generalized transfer matrix method thereby considering the mixed coherent/incoherent layer stacking. Moreover, the intrinsic recombination mechanisms and their importance in a narrow bandgap semiconductor were also taken into account. In this regard, the parabolic band approximation and Fermi's golden rule were combined for an accurate estimation of the radiative recombination rate. Based on these analyses, power conversion efficiencies of up to 9% are predicted for Ge<inline-formula><tex-math notation=\"LaTeX\">$_{0.83}$</tex-math></inline-formula>Sn<inline-formula><tex-math notation=\"LaTeX\">$_{0.17}$</tex-math></inline-formula> thermophotovoltaic cells under black-body radiation at temperatures in the 500–<inline-formula><tex-math notation=\"LaTeX\">$1500 ,mathrm{K}$</tex-math></inline-formula> range. A slight improvement in the efficiency is observed under the frontside illumination but vanishes below <inline-formula><tex-math notation=\"LaTeX\">$800 ,mathrm{K}$</tex-math></inline-formula>, while the use of a backside reflector improves the efficiency across the investigated black-body temperature range. The effects of the heterostructure thickness, surface recombination velocity, and carrier lifetime are also elucidated and discussed.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"13 5","pages":"728-735"},"PeriodicalIF":3.0,"publicationDate":"2023-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3490877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-20DOI: 10.1109/JPHOTOV.2023.3284588
Kenji Kamide;Hidetaka Takato
We present a design theory for a two-terminal series perovskite (PVK)/silicon (Si) tandem solar cell. The development of this device requires PVK materials with a wide bandgap of about 1.7 eV for current matching with Si. On the other hand, in the current state of research and development, high quality as a single PVK cell has been obtained with materials having a lower bandgap (<1.6 eV). In this article, we focus on a design in which the top and bottom cells are divided into multiple cells and connected in series as an approach to adjust the current matching condition that limits the bandgap of the top cell, clarify its optimization and effectiveness by model calculations, and present an example of an optimal monolithic design.
{"title":"A Current Matching Design and Its Impact of High-Efficiency Two-Terminal Perovskite/Silicon Tandem Photovoltaics","authors":"Kenji Kamide;Hidetaka Takato","doi":"10.1109/JPHOTOV.2023.3284588","DOIUrl":"https://doi.org/10.1109/JPHOTOV.2023.3284588","url":null,"abstract":"We present a design theory for a two-terminal series perovskite (PVK)/silicon (Si) tandem solar cell. The development of this device requires PVK materials with a wide bandgap of about 1.7 eV for current matching with Si. On the other hand, in the current state of research and development, high quality as a single PVK cell has been obtained with materials having a lower bandgap (<1.6 eV). In this article, we focus on a design in which the top and bottom cells are divided into multiple cells and connected in series as an approach to adjust the current matching condition that limits the bandgap of the top cell, clarify its optimization and effectiveness by model calculations, and present an example of an optimal monolithic design.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"13 5","pages":"699-704"},"PeriodicalIF":3.0,"publicationDate":"2023-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3517618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For more than three decades, Cu has been critical to dope CdSeTe solar cells, form effective contacts, and maximize efficiency. At the same time, Cu defect chemistry has limited stability, carrier concentration, and further efficiency improvements. In this article, 22.3% world record efficiency is demonstrated without Cu by implementing As doping, which also improves stability, temperature coefficient, and energy yield. The efficiency crossing point of Group V technology relative to Cu has been driven by steady improvements in the open-circuit voltage. Here, the certified record cell reaches open-circuit voltage of 899 mV while retaining high photocurrent values of 31.4 mA/cm 2 ; the fill factor is relatively low at 78.9%. Coupling 80% fill factor with top open-circuit voltage values of 917 mV reported here offers a near-term path to 23% efficiency. Characterization indicates reducing recombination and improving activation provide viable paths to 25% efficiency.
{"title":"Arsenic-Doped CdSeTe Solar Cells Achieve World Record 22.3% Efficiency","authors":"R. Mallick;X. Li;C. Reich;X. Shan;W. Zhang;T. Nagle;L. Bok;E. Bicakci;N. Rosenblatt;D. Modi;R. Farshchi;C. Lee;J. Hack;S. Grover;N. Wolf;W.K. Metzger;D. Lu;G. Xiong","doi":"10.1109/JPHOTOV.2023.3282581","DOIUrl":"https://doi.org/10.1109/JPHOTOV.2023.3282581","url":null,"abstract":"For more than three decades, Cu has been critical to dope CdSeTe solar cells, form effective contacts, and maximize efficiency. At the same time, Cu defect chemistry has limited stability, carrier concentration, and further efficiency improvements. In this article, 22.3% world record efficiency is demonstrated without Cu by implementing As doping, which also improves stability, temperature coefficient, and energy yield. The efficiency crossing point of Group V technology relative to Cu has been driven by steady improvements in the open-circuit voltage. Here, the certified record cell reaches open-circuit voltage of 899 mV while retaining high photocurrent values of 31.4 mA/cm\u0000<sup>2</sup>\u0000; the fill factor is relatively low at 78.9%. Coupling 80% fill factor with top open-circuit voltage values of 917 mV reported here offers a near-term path to 23% efficiency. Characterization indicates reducing recombination and improving activation provide viable paths to 25% efficiency.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"13 4","pages":"510-515"},"PeriodicalIF":3.0,"publicationDate":"2023-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/5503869/10192919/10155462.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3496859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-14DOI: 10.1109/JPHOTOV.2023.3282895
Kwong-Kit Choi;Zunaid Omair;Patrick Oduor;Achyut K. Dutta
A thermophotovoltaic (TPV) power generation system based on resonator-pixel (RP) emitters and photovoltaic (PV) cells is proposed. The RP structure enables wavelength-selective emission and absorption, which increases the system power throughout and efficiency. An RP structure contains a thin semiconductor material etched into an array of micron-sized rings and covered with a metal layer. The emissivity of the RP emitter is determined by equating it to absorptivity and is modeled by three-dimensional electromagnetic modeling. The result shows that the emitter is able to increase the wavelength selectivity by eight times compared to a bulk emitter. Integrated with an RP PV cell having enhanced absorption at the band edge, the power conversion efficiency can be maintained constant in a wide range of temperatures, while the power throughput increases by 1.7 times. In addition, the RP emission is highly directional. Its far-field beamwidth is less than 10°, with which the emitter and PV cell can be placed at a larger distance to avoid convectional heating on the PV cell. In this work, we also confirm a near-field TPV effect that raises the electrical power by a factor of 2 when the emitter and cell are placed less than 2 μ m apart.
{"title":"Resonant Thermal Emitters and PV Cells for Thermophotovoltaic Power Generation","authors":"Kwong-Kit Choi;Zunaid Omair;Patrick Oduor;Achyut K. Dutta","doi":"10.1109/JPHOTOV.2023.3282895","DOIUrl":"https://doi.org/10.1109/JPHOTOV.2023.3282895","url":null,"abstract":"A thermophotovoltaic (TPV) power generation system based on resonator-pixel (RP) emitters and photovoltaic (PV) cells is proposed. The RP structure enables wavelength-selective emission and absorption, which increases the system power throughout and efficiency. An RP structure contains a thin semiconductor material etched into an array of micron-sized rings and covered with a metal layer. The emissivity of the RP emitter is determined by equating it to absorptivity and is modeled by three-dimensional electromagnetic modeling. The result shows that the emitter is able to increase the wavelength selectivity by eight times compared to a bulk emitter. Integrated with an RP PV cell having enhanced absorption at the band edge, the power conversion efficiency can be maintained constant in a wide range of temperatures, while the power throughput increases by 1.7 times. In addition, the RP emission is highly directional. Its far-field beamwidth is less than 10°, with which the emitter and PV cell can be placed at a larger distance to avoid convectional heating on the PV cell. In this work, we also confirm a near-field TPV effect that raises the electrical power by a factor of 2 when the emitter and cell are placed less than 2 \u0000<italic>μ</i>\u0000m apart.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"13 5","pages":"716-727"},"PeriodicalIF":3.0,"publicationDate":"2023-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3505948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-28DOI: 10.1109/JPHOTOV.2023.3269118
Martin Springer;Timothy J. Silverman;Nick Bosco;Junki Joe;Ingrid Repins
Predictive modeling tools such as the finite element method can be of tremendous help in assessing the reliability and long-term performance of photovoltaic modules. In order to obtain accurate results, the proper modeling of materials and manufacturing processes are of utmost importance. Module fabrication introduces thermo-mechanical stresses inside the module laminate, which need to be accounted for as residual stresses in finite element simulations. We found that cell fragment movement and crack opening displacements of fractured silicon cells within modules are affected by those residual stresses. Cell cracking remains a challenging topic in assessing the reliability and durability of damaged modules. Hence, accurately quantifying the separation and movement between cell fragments creates the foundation for establishing reliable lifetime and performance assessments of fractured silicon modules. We present a modeling approach that uses upper and lower bounds to accurately account for the residual stresses introduced by the module lamination process. We designed a four-point flexure coupon test of a laminated, fractured silicon strip to validate our numerical results and found good agreement between our modeling methodology and the experimental data. Finally, we discuss the implications of the residual stresses on the normal crack opening and metallization wear-out of fractured silicon cells.
{"title":"Residual Stresses Affect Cell Fragment Movement","authors":"Martin Springer;Timothy J. Silverman;Nick Bosco;Junki Joe;Ingrid Repins","doi":"10.1109/JPHOTOV.2023.3269118","DOIUrl":"https://doi.org/10.1109/JPHOTOV.2023.3269118","url":null,"abstract":"Predictive modeling tools such as the finite element method can be of tremendous help in assessing the reliability and long-term performance of photovoltaic modules. In order to obtain accurate results, the proper modeling of materials and manufacturing processes are of utmost importance. Module fabrication introduces thermo-mechanical stresses inside the module laminate, which need to be accounted for as residual stresses in finite element simulations. We found that cell fragment movement and crack opening displacements of fractured silicon cells within modules are affected by those residual stresses. Cell cracking remains a challenging topic in assessing the reliability and durability of damaged modules. Hence, accurately quantifying the separation and movement between cell fragments creates the foundation for establishing reliable lifetime and performance assessments of fractured silicon modules. We present a modeling approach that uses upper and lower bounds to accurately account for the residual stresses introduced by the module lamination process. We designed a four-point flexure coupon test of a laminated, fractured silicon strip to validate our numerical results and found good agreement between our modeling methodology and the experimental data. Finally, we discuss the implications of the residual stresses on the normal crack opening and metallization wear-out of fractured silicon cells.","PeriodicalId":445,"journal":{"name":"IEEE Journal of Photovoltaics","volume":"13 4","pages":"547-551"},"PeriodicalIF":3.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"3496868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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