2.8 Mio Euro Funding for preparing perovskite solar cells for high volume manufacturing
HZB participates in a new consortium for Perovskite solar technology that is led by Oxford PV Germany GmbH. The consortium is funded by the German Ministry of Economics and Energy with 2.8 Million Euros and aims to further demonstrate the manufacturability of perovskite-silicon tandem solar cells. (24.08.2018)
Further partners are Von Ardenne GmbH, Fraunhofer-Institute for Solar Energy Systems ISE, and the Technical University of Berlin. The project will focus on preparing perovskite solar cell technology for high volume manufacturing. This will include the optimisation of the perovskite-silicon tandem solar cell architecture, to make further efficiency improvements on industrial 156 mm x 156 mm wafer formats; the refinement of industrial scale process technology; and life-cycle analysis to inform the social-environmental impact of the tandem solar cells.
"Perovskite-based tandem solar cells are very promising to achieve really high efficiencies. In order to contribute to this exciting development we have built up strong competences in perovskites and tandem cell technology such as the Helmholtz Innovation Lab HySPRINT", says Prof. Dr. Rutger Schlatmann, Director of the Competence Center Thin Film and Nanotechnology for Photovoltaics Berlin (PVcomB) at HZB. "To the consortium with Oxford PV, we contribute our vast expertise in high-efficiency silicon heterojunction bottom cells", adds Dr. Bernd Stannowski who is leading these activities at the PVcomB.
Dr. Chris Case, Chief Technology Officer at Oxford PV says “The consortium partners bring together the perfect balance of expertise. Refining the manufacturing process of our perovskite solar cell technology will ensure the highest performing tandem solar cell in the field and the easy transfer of our technology into silicon solar cell and module production lines.”
In June 2018, HZB and Oxford achieved an independently certified efficiency of 25.2 % for their perovskite silicon tandem solar cell. “In our cooperation, we aim to further optimize perovskite silicon tandem cells, demonstrate their scalability and facilitate their integration into large-area solar modules”, says Rutger Schlatmann.
Wirkungsgrad von 25,2 % für Perowskit-Silizium-Tandem-Solarzelle zertifiziert
A 1 cm2 perovskite silicon tandem solar cell achieves an independently certified efficiency of 25.2 %. This was presented this week at an international conference in Hawaii, USA. The cell was developed jointly by HZB, Oxford University and Oxford PV - The Perovskite CompanyTM. (14.06.2018)
"Perovskite-based tandem solar cells can use light particularly efficiently and therefore offer the opportunity to achieve even higher efficiencies. That is why we have significantly expanded our expertise with the new Helmholtz innovation laboratory HySPRINT," says Prof. Dr. Rutger Schlatmann, Director of the Competence Center Thin Film and Nanotechnology for Photovoltaics Berlin (PVcomB) at HZB. "In our cooperation with Oxford PV, we aim to further optimize perovskite silicon tandem cells, demonstrate their scalability and facilitate their integration into large-area solar modules. For this new result we have optimized our high-efficiency silicon heterojunction bottom cell and developed an optical adaptation to the top cell using a very specific SiOx intermediate layer".
At the World Conference on Photovoltaic Energy Conversion, WCPEC-7 in Waikoloa, Hawaii, tandem solar cells involving perovskites were an important topic: two records have been presented with 25.2% certified efficiency: one from the group of Prof. Christophe Ballif at EPFL/CSEM and one from the consortium HZB/OxfordPV/Oxford University, presented by HZB scientist Dr. Bernd Stannowski. The third one, with 25.0% certified efficiency is a tandem cell developed by an HZB team headed by Dr. Steve Albrecht.
Oxford PV was established in 2010 and has had a close working relationship with Professor Snaith’s research group at the University of Oxford. In January 2018, Oxford PV announced its collaboration with HZB, the leading German research centre focused on energy materials research.
Silicon heterojunction solar cell with a certified 23.1 % energy conversion efficiency.
After further optimization of the baseline process for industrial silicon heterojunction (SHJ) solar cells, the accredited metrology lab ISFH CalTeC now certified an efficiency of 23.1 % for a 4 cm² solar cell. This performance is among the best in the world demonstrates the leading role of HZB in this technology in Germany and Europe.
Within the institute PVcomB at HZB we develop SHJ cells with the focus on improving industrial applicable materials and processes in collaboration with industry partners (e.g. Meyer Burger, Von Ardenne, Singulus). Moreover, new types of solar cells with the potential to surpass the efficiency limit of silicon-based cells, such as perovskite/SHJ tandem junctions, are developed at HZB, partially in collaboration with industry (Oxford PV). Results will be presented this year at the international PV conferences WCPEC (June 10-15, Hawaii) and EUPVSEC (Sep 24-28, Brussels).
Silicon heterojunction (SHJ) solar cells are made of crystalline silicon wafers using passivated contacts for both polarities based on i/n and i/p stacks of thin-film silicon alloys, such as amorphous silicon, nano-crystalline silicon or silicon oxide. Due to a high silicon wafer quality and the excellent surface passivation SHJ solar cells reach very high conversion efficiencies with highest open circuit voltages >740 mV and low temperature coefficient <0.3 %/K. With this type of two-side contacted cell Kaneka Corp. (Japan) holds the world record with a 25.1 % conversion efficiency. Recently, they attracted attention with 26.7 % for an all-rear-side contacted (IBC) SHJ cell, which is currently the world record for a silicon-based solar cell. For commercial production, the lean process sequence consisting of only four major process steps, all below <200°C processing temperature, facilitate cost-effective cell production.
PVcomB and AVANCIS launch joint MyCIGS research project in order to improve outdoor performance of thin film CIGS solar modules
The Competence Centre Thin-Film- and Nanotechnology for Photovoltaics Berlin (PVcomB) is contributing its expertise to improving copper-indium-gallium-sulphide (CIGS) thin-film production in the MyCIGS collaborative research project. CIGS-module manufacturer AVANCIS in Munich is coordinating this project funded by the German Federal Ministry for Economic Affairs and Energy (BMWi). The Carl von Ossietzky University of Oldenburg (Oldenburg University) and Friedrich-Alexander-Universität Erlangen-Nuremberg (FAU) are also partners in the project.
Thin-film solar modules based on copper-indium-gallium-diselenide compounds, or CIGS for short, are highly efficient, economical, and versatile.  Thanks to their special properties, they can be employed not just on roofing, but for building cladding as well. Building-integrated Photovoltaics (BIPV) offer diverse new aesthetic configurations for architecture and will find a place on many more surfaces in urban environments.
Improvement in energy yield
Whereas module efficiency has been the focus of previous projects, the MyCIGS project will address how to optimise the energy yield in actual applications, i.e. under realistic conditions of outdoor use. In addition to the efficiency, additional properties such as the temperature coefficients and the power output under conditions of low or diffuse illumination are critical factors. These also play an important role when employing CIGS modules in cladding and buildings.
Expertise at PVcomB in CIGS thin film technology
“We have a lot of experience at PVcomB with characterising and tuning the performance of CIGS thin-films”, explains Dr. Reiner Klenk, in charge of the MyCIGS Project at PVcomB. Using the numerous measurement techniques that have been established at PVcomB, major parameters like temperature coefficients and behaviour under low light conditions can be traced back to physical processes in the solar module. The research project fits in with PVcomB’s strategy of going beyond manufacturing technologies and to also address topics such as encapsulation, reliability, outdoor measurements, and building integration.
New Outdoor Performance research group
As part of the Helmholtz Energy Systems Integration Project for the Future, a new research group headed by Dr. Carolin Ulbrich has just been established. This research group will now be able to measure the energy yields of CIGS modules as well as acquire data sets on local incident radiation and temperature by means of a outdoor testing platform at PVcomB.
AVANCIS and PVcomB utilise differing technologies and materials in fabricating the individual layers of solar modules. Differing layers made by the project partners can be combined, thereby generating a combinatorial set of baseline data with which the influence of manufacturing technologies on the energy yield can be determined more accurately.
In addition, MyCIGS will benefit from the current PEARL TF-PV solar-era.net project in which PVcomB is augmenting its expertise in defect analysis of CIGS solar modules through collaboration with its German, Dutch, and Austrian institutional research partners, module manufacturers, and solar power station designers.
PVcomB @ EUPVSEC 2017
The world's largest photovoltaic scientific conference takes place from 25-29 September this year in Amsterdam. As in the last years, scientists from PVcomB will present their latest results in PV R&D and discuss the recent developments and technological challenges with colleagues from worldwide research and industry.
If you like to meet us in Amsterdam to discuss scientific questions or if you are looking for a reliable partner in a joint project, don't hesitate to contact us by firstname.lastname@example.org.
The following contributions we are going to present during the conference:
BIPV – Bridging the Gap between PV Industry Supply and Construction Industry Demand (Parallel event, Tuesday, 26 September)
"Overview on European BIPV development"
"Nanocrystalline vs. Amorphous n-Type Silicon Front Surface Field Layers in Silicon Heterojunction Solar Cells: Role of Thickness and Oxygen Content"
A.B. Morales-Vilches, L. Mazzarella, M. Hendrichs, L. Korte, R. Schlatmann, B. Stannowski
"Influence of the Precursor Layer Composition and Deposition Processes on the Electronic Quality of Liquid Phase Crystallized Silicon Absorbers"
D. Amkreutz, N. Preissler, P. Sonntag, C. Thi-Trinh, R. Schlatmann, B. Rech
"In Situ Analysis of the In-Ga Inter-Diffusion in Cu(In,Ga)Se2 Absorbers during Rapid Selenisation at High Se Pressure"
J. Marquez-Prieto, H. Stange, S. Levcenko, J.-P. Bäcker, T. Kodalle, A. Redinger, S.S. Schmidt, M. Klaus, C. Genzel, R. Schlatmann, T. Unold, R. Mainz
"Stacking Fault Annihilation through Grain Growth in Chalcopyrite Thin Films: A Model Supported by Simulation and In-Situ XRD"
H. Stange, S. Brunken, D. Greiner, M.D. Heinemann, S.S. Schmidt, J.-P. Bäcker, C.A. Kaufmann, M. Klaus, C. Genzel & R. Mainz, D.A. Barragan Yani, L.A. Wägele, R. Scheer
"Sub-Micrometer Resolved Electroluminescence Measurements on CZTSe and CIGSe Thin Film Solar Cells"
A. Redinger, S. Levcenko, J.M. Marquez-Prieto, D. Greiner, C.A. Kaufmann, T. Unold, E. Saucedo, S. Giraldo
"Micro concentrator concept for cost reduction and efficiency enhancement of thin-film chalcopyrite photovoltaics: Results from EU joint research program CHEETAH"
M. Schmid, E. Lotter, X. Lin, L. Wang, R. Klenk, K. Eylers, F. Ringleb, T. Boeck, B. Heidmann1 G. Nenna, F. Loffredo, F. Villani, T. Köhler, D. Sancho-Martinez, T. Raadik, J. Krustok, M. Grossberg, M.Ch. Lux-Steiner
"Monolithic integration scheme for CIGS micro concentration solar cells"
G. Farías Basulto, T. Köhler, B.Stannowski, C. A. Kaufmann, R. Klenk
"Numerical Optical Optimization of Perovskite-Silicon Tandem Solar Cells"
K. Jäger, M. Werth, L. Mazzarella, S. Calnan, F. Ruske, L. Korte, B. Stannowski, B. Rech, S. Albrecht
"Rear-Side Contacted, Laser-Structured CIGSe Cells: A Proof of Concept"
G. Farías Basulto, M.D. Heinemann, C.A. Kaufmann, B. Rau, R. Schlatmann; C. Schultz, B. Stegemann
"Investigation of KF-PDT Induced Surface Modification of Cu(In,Ga)Se2 Absorbers and
Its Correlation with Device Performance"
I. Majumdar, V. Parvan, D. Greiner, R. Schlatmann, I. Lauermann, M.Ch. Lux-Steiner
"Laser patterning of perovskite solar cells: Process development for monolithic serial interconnection"
C. Schultz, F. Schneider, C. Ferber, L. Kegelmann, S. Meyer, B. Rech, R. Schlatmann, S. Albrecht, B. Stegemann
"FP7-CHEETAH Knowledge Exchange Platform: Results and their Exploitation"
F. Roca, D. Casaburi, F. Beone, C. Diletto, I. Falcone, A. De Girolamo, R. Miscioscia, I. Lauermann, M. Schmid, S.A. Gevorgyan, I. Gordon, K. Van Nieuwenhuysen, A. Roesch, A. Danel, P. Sommeling, J. Kroon, S.C. Veenstra, S. Binetti, T. Boeck, F. Ringleb, F. Brunetti, A. Di Carlo, J. Bowers, S. Buecheler, J. Cárabe, J.F. Trigo, C. del Cañizo, M. Grossberg, G. Halambalakis, J. Hast, A. Joyce, R. Kvande, E. Lotter, E. Román, R. Turan, G. Sánchez-Plaza, N. Wyrsch, S. Zamini
Silicon heterojunction solar cell baseline with certified 22.5 % cell conversion efficiency
The PVcomB baseline process for industrial silicon heterojunction (SHJ) solar cells has achieved state-of-the-art level, yielding cell efficiencies above 22 %. In less than two years we reached a new milestone. The ISFH CalTeC now certified an efficiency of 22.54 % for a 4 cm² SHJ cell from the PVcomB baseline. Full-size cells (156 x 156 cm²) are being optimized and already reach conversion efficiencies well above 20%.
Silicon heterojunction (SHJ) solar cells are made of crystalline silicon wafers using passivated contacts for both polarities based on i/n and i/p stacks of thin-film silicon alloys, such as amorphous silicon (a-Si:H), nanocrystalline silicon (nc-Si:H) or silicon oxide (nc-SiOx:H). Due to a high silicon wafer (Cz-Si) quality and the excellent surface passivation SHJ solar cells reach very high conversion efficiencies with highest open circuit voltages >740 mV and low temperature coefficient <0.3 %/K. For commercial production, the lean process sequence consisting of only four major process steps, all below <200°C processing temperature, facilitate low-cost cell production. Recently, Kaneka Corp. (Japan) attracted attention with 26.6 % for an all-rear-side contacted (IBC) SHJ cell (world record for a silicon-based solar cell), demonstrating the high potential of the SHJ technology .
In the Silicon PV Group at PVcomB we develop SHJ cells with the focus on improving industrial applicable materials and processes.
By combining the strong background in thin-film technology at PVcomB with the existing know-how of the HZB institute of silicon photovoltaics and introducing the industrial screen-printing technology for grid metallization we set up an industrial-type baseline process in rather short time. Besides direct applications in industry the SHJ technology is very attractive for various future types of solar-energy conversion devices. Therefore, at HZB we adressing the following research topics:
- New processes to be implemented for high-efficiency SHJ cells in cooperation with PV industry.
- SHJ bottom cell in novel high-efficiency multi-junction (“tandem”) cells, e.g. with perovskite top cells.
- PV cells and modules adapted for hydrogen generation (“solar fuels”).
- Advanced silicon-based passivating contact layers for novel types of silicon-based solar cells, such as liquid-phase crystallized silicon (LPC-Si) solar cells on glass.
 “Silicon heterojunction solar cell with interdigitated back contacts for a photoconversion efficiency over 26%”, Kunta Yoshikawa, Hayato Kawasaki, Wataru Yoshida, Toru Irie, Katsunori Konishi, Kunihiro Nakano, Toshihiko Uto, Daisuke Adachi, Masanori Kanematsu, Hisashi Uzu and Kenji Yamamoto,
NATURE ENERGY 2, 17032 (2017) DOI: 10.1038/nenergy.2017.32.
Fig.: Silicon Heterojunction solar cell from the PVcomB Baseline with 22.5% conversion efficiency certified by ISFH CalTeC. (photos: HZB)
PVcomB will help mass-produce the raw photovoltaic materials used in Wysips® technology (Jan 2017)
Sunpartner Technologies and Helmholtz-Zentrum Berlin sign license agreement
The French company Sunpartner Technologies has been developing innovative solar solutions for nearly 10 years. One of these is Wysips,® an invisible or transparent photovoltaic film that transforms any surface into a solar panel that can generate electricity using the sun’s light. To create Wysips® Crystal and Wysips® Reflect, Sunpartner Technologies paired with the German research centre Helmholtz-Zentrum Berlin (HZB) to develop a special solar material that could be integrated into the company’s technology.
The Wysips® Crystal component is an ultra-thin, transparent glass that combines photovoltaic material with an optical system adapted to display screens like those used in cell phones and connected watches. The component provides the device with a constant power reserve, ensures that certain applications work properly, and independently powers certain operations. For example, exposing a phone to the sun for three minutes will give you one minute of call time.
The goal of Wysips® Reflect is to make connected watches last as long as possible in between recharges. It extends battery life by up to 50% on products it has been applied to, depending on product energy use. The component is completely invisible and can be integrated into a digital or analog watch without affecting its design.
The Competence Centre Thin-Film- and Nanotechnology for Photovoltaics Berlin (PVcomB) at Helmholtz-Zentrum Berlin (HZB) is a trusted supplier of photovoltaic cells and was involved in developing one of the key building blocks in these two Wysips® components: a special photovoltaic material compatible with the transparency process developed by Sunpartner Technologies.
HZB relied on Sunpartner Technologies’ specifications to determine the stacking order that makes up the special photovoltaic material, the quality and thickness of the glass substrate, the formats, and the tolerance levels for cleanness and dust. The result is a turnkey solution, called a “photovoltaic stack,” that Sunpartner Technologies renders transparent or invisible to the naked eye by means of its own proprietary processes.
The French company, whose production unit is located in Rousset, is currently preparing to mass-produce its components. The company and HZB therefore signed a license agreement that allows Sunpartner Technologies to use HZB’s expertise to develop Wysips® Crystal and Wysips® Reflect.
Franck Aveline, VP Consumer Product Line at Sunpartner Technologies, said, “We are very pleased with our collaboration with the Helmholtz-Zentrum Berlin laboratory. They sought to understand us and meet our needs by sharing their expertise and technical abilities with us in the field of thin photovoltaic film. This agreement is a new step we’re taking together towards industrializing Wysips® solutions while still maintaining control of the key technological building blocks we need to develop.”
Bernd Stannowski, senior scientist at HZB, said, “This collaboration allows us to bring our high-efficiency thin-film silicon solar cell technology developed over the past five years to industrialization. With Sunpartner we found an ideal partner to further develop and transfer to production.”
About Sunpartner Technologies:
Sunpartner Technologies develops and integrates innovative and invisible photovoltaic solutions for the consumer electronics (wearables, mobile devices, connected objects), building (Smart Cities), and transportation (automobile, aviation, maritime) markets. Its Wysips® technology (short for “What You See Is Photovoltaic Surface”) captures solar energy and converts it to electricity so that ordinary objects require no or almost no outside energy source. The company puts its expertise to work to create smart, attractive surfaces around the world. Sunpartner Technologies was founded in 2008 in Rousset, France, and today has 65 employees and a large portfolio of patents. The company has raised 45 million Euros since its creation.
Speeding up CIGS solar cell manufacture
Speeding up CIGS solar cell manufacture
A project consortium from research and industry involving the Competence Centre for Photovoltaics Berlin (PVcomB) of Helmholtz-Zentrum Berlin has been granted a major third-party-funded project by the Federal Ministry of Economics. The project “speedCIGS” is to be funded with 4.7 million euros over four years, of which 1.7 million goes to HZB. The project partners will use this money to accelerate the manufacturing process for CIGS thin-film solar cells and thus make the technology more attractive to industry.
The speedCIGS project is being carried in cooperation with systems builder Manz AG, the Center for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW), the Universities of Jena and Paderborn, the Max Planck Institute Dresden and the Wilhelm Büchner Hochschule (as project coordinator).
The acquired funding will go towards optimising a co-evaporation process at PVcomB used for producing CIGS layers for thin-film solar cells. CIGS solar cells get their name from their constituent elements Copper, Indium, Gallium and Selenium. The elements are deposited together in a vacuum onto a heated substrate to form a thin layer of the desired compound. The manufacturing process used at PVcomB is already being used industrially, but is still relatively slow. The process is now to be sped up within the speedCIGS project, so that more modules can be produced per unit time for the same investment costs. This would make the production of CIGS solar modules much cheaper, giving the technology a competitive advantage in the currently tense market situation.
Also to be developed at PVcomB is a transparent p-conducting material that will go a long way towards developing high-efficiency tandem solar cells based on CIGS.
Polycrystalline CIGS solar cells already stand out for their high efficiency and high energy yields. Another advantage is the aesthetic appearance of the modules, which integrate pleasingly into building architectures.
IW-CIGSTech7 - HZB and ZSW organize CIGS Workshop in Munich (June 2016)
This time, the "7th International Workshop on CIGS solar cell technology (IW-CIGSTech7)" will take place as a parallel event at the EUPVSEC 2016 in Munich. In 2016, HZB and ZSW join their forces to offer IW-CIGSTech7 as a parallel event at the 32nd European PV Solar Energy Conference and Exhibition, EUPVSEC. IW-CIGSTech 7 will take place as a full-day event on Thursday, 23rd of June, 2016, including an evening event in downtown Munich. The workshop concentrates on CIGS solar cell technologies and combines Science and technological aspects with their industrial applications. The workshop will consist of invited talks, discussions and poster presentations. As an EUPVSEC delegate (full week or any one day ticket), you will be able to participate in IW-CIGSTech 7 free of charge. Further information are availabe here.
ACCESS-CIGS - Finacial support for improving the manufacturing processes of CIGS solar cells (May 2016)
PVcomB has gained a large project for the further improvement of the manufacturing process for CIGS thin-film solar cells together with partners from Germany and the Netherlands. The atmospheric pressure process operates without involving toxic gases and will be more economical. It will run under the acronym ACCESS-CIGS, which stands for “Atmospheric European Cooperation in Science and Technology (COST) Competitive Elemental Sulpho-Selenisation for CIGS”.
Experts at the Competence Centre Thin-Film- and Nanotechnology for Photovoltaics Berlin (PVcomB) in Adlershof are developing an innovative process to fabricate CIGS layers for application in thin-film solar cells. CIGS stands for the compound Cu(In,Ga)(Se,S)2, consisting of copper, indium, gallium, selenium and sulphur. Polycrystalline CIGS solar cell technology is noted for its high efficiencies at the solar-cell level and high energy yields for solar modules.
The process pursued at PVcomB does not require a vacuum and utilises elementary selenium and sulphur to convert the metallic precursor layer of copper-indium-gallium to a polycrystalline CIGS semiconductor layer. This has the advantage that the process can be carried out without the use of toxic gases such as hydrogen selenide (H2Se), saving on production costs. This might permit the manufacture of CIGS solar modules to be considerably more economical and thus support the currently difficult market situation.
PVcomB has been successful in attracting funding of 800 000 EUR under the SOLAR-ERA.NET Initiative. Staff will be working on the technology as part of a bi-national European consortium over the next two years to optimise the addition of selenium and improve its influence on the crystallisation process.
The project will be carried out in cooperation with the companies TNO/Solliance and Smit Thermal Solutions, both located in Eindhoven, Netherlands, and with the firm Dr. Eberl MBE Komponenten in Weil der Stadt on the German side.
Why Investing in CIGS thin-film photovoltaics is profitable (December 2015)
Photovoltaic industry and research institutes publish "White Paper for CIGS Thin-Film Solar Cell Technology"
Most home owners should have realized by now that it is still worthwhile for them to invest in solar power. The advantages awaiting business companies, banks and investors who choose the highly efficient CIGS thin-film technology are explained in the new White Paper for CIGS Thin-Film Solar Cell Technology. 30 renowned CIGS experts, among Rutger Schlatmann, Martha Lux-Steiner and Hans-Werner Schock from HZB, send a clear message: ‘The time to invest is now!’.
The unique selling propositions for the special solar modules named after their absorber layer made from the elements copper (Cu), indium (In), gallium (Ga) and selenium (Se) or sulphur (S) are their high efficiencies (laboratory cell 22.3 %, module 16.5 %), high yields even under low light conditions and low electricity costs. For the near future, further progress is expected in the development leading to even higher efficiencies and further cost reduction. In addition, the CIGS experts emphasize the versatile product’s sustainability because of its low consumption of energy and materials during production and the short energy payback time associated with it.
More information and the 4-page White Paper for download is available at www.cigs-pv.net.
Double paper award at PVSEC-25 (November 2015)
Two PVcomB contributions awarded at PVSEC-25, Busan, Korea
Two contributions of the HZB were awarded at the 25th International Photovoltaic Science & Engineering Conference in Busan, Korea. The presentations of both Jan-Peter Bäcker and co-authors and of Marc Daniel Heinemann and co-authors have recieved the PVSEC-25 Paper Award for their excellent contributions in the field of CIGS solar cell research.
Jan-Peter Bäcker and co-authors presented their work about phase separation in Cu-In-Ga precursor layers for sequentially processed CIGSe solar cells.
"Phase separation and coarsening in Cu-In-Ga precursor thin films for sequentially processed Cu(In,Ga)Se2 solar cells"
J.P. Bäcker1, S.S. Schmidt1, M. Hartig3, C.A. Kaufmann1, R. Mainz2, H. Rodriguez-Alvarez1, C. Wolf1, R. Schlatmann1,
1 PVcomB / Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany
2 HZB für Materialien und Energie, Hahn Meitner Platz 1, D-14019 Berlin, Germany
3 PVcomB / Technische Universität, Straße des 17. Juni 135, D-10623 Berlin, Germany
"Obtaining smooth and homogenous Cu(In,Ga)Se2 films by fast selenization of metallic precursors is a major challenge. Separation and coarsening of metallic phases in Cu-In-Ga precursor films can lead to solar cells with low shunt resistance due to pinhole formation, and to reduced open circuit voltages due to locally varying Ga content and compositional depth-profiles. The scale of this phase separation depends on the initial precursor microstructure, the heating rates, the temperature and the chalcogenization procedure. The processing is assisted by a liquid phase, as expected from the calculated phase diagram of the Cu-In-Ga system. Due to its complexity, this aspect has been neglected in the past and most studies are limited to the mere observation of morphologies before and after the chalcogenization process. In this study we attempt to establish a better understanding of the film, before and during the RTP process of sputtered Cu-Ga-In metallic precursor as used for sequential high efficiency solar cell fabrication. For this we measure the roughness with atomic force microscopy and the Ga spatial distribution by energy dispersive X-ray spectroscopy. We study eight different metallic precursor stacks including the influence of different sodium sources / layers. The range of parameters consists of heating to 170 °C, 350 °C and 580 °C, at rates between 0.01 K/s and 10 K/s. This covers the experimental window relevant for selenizations in H2Se atmosphere and for rapid selenizations in elemental Se-vapor. Based on this comprehensive data we propose optimized precursor stacks and heating profiles for pre-heating treatments before the chalcogenization takes place. The main objective is to homogenize and alloy the Cu-poor Cu-In-Ga metallic precursor without significant phase separation or increase in roughness.
Finally, we present a statistical analysis of the effect of our optimized and multilayered precursor layers on the fill factor of the solar cells prepared in our atmospheric-pressure in-line and fast selenization baseline that has led to power conversion efficiencies of up to 15.5 %."
Marc Daniel Heinemann and his co-authorspresented their work about CIGS solar cells in superstrate configuration.
"Revival of CIGSe Superstrate Solar Cells?"
M.D. Heinemann1, J. Berry4, D. Greiner1, M. Wollgarten2, T. Unold3, R. Klenk1, H.-W. Schock1, D. Ginley4, R. Schlatmann1, C. A. Kaufmann1,
1 PVcomB / Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany
2 EE-IN / Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz, 14109 Berlin, Germany
3 EE-AKV / Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz, 14109 Berlin, Germany
4 National Renewable Energy Laboratory, Golden, Colorado 80401
"CIGSe solar cells in superstrate configuration give the promise to achieve an improved light yield and higher stability compared to substrate devices, but they haven’t delivered comparable power conversion efficiencies yet. Chemical reactions between the CIGSe and the buffer layer were shown in the past to deteriorate the p/n-junction, which leads to the lower efficiencies compared to the substrate-type device. However existing studies on the interface between CIGSe and Oxides have failed to develop an understanding of the correlation between the interface properties with the device properties. In this work interface analysis by TEM and XPS, combined with device analysis by numerical simulations were used to establish this correlation for CIGSe co-evaporated onto ZnO. The obtained results were used to find solutions to overcome the limitations, which were induced by the Na and Cu diffusion into the oxide materials.
To find suitable oxide buffer layer, a combinatorial material deposition approach was used to find the material with the optimum electron affinity, doping density and chemical stability. The best results were obtained with amorphous Ga2O3 as the buffer layer material, whose electron affinity was found to be comparable to the one of CIGSe. However, interfacial acceptor states were found to be present at the interface between CIGSe and Ga2O3 and the n-type doping density of the Ga2O3 layer was not sufficient to compensate these. First experiments indicate how to further increase the doping densities to above 1e+19 cm-3 to sufficiently compensate the interfacial acceptor states. Further, it is shown how to apply compositional gradients of S and Ga within the superstrate configuration, how the ZnO annealing increases the light yield and the oxide/metal highly reflective back contact allows a CIGSe thickness reduction down to 800 nm without efficiency losses. Currently a stable efficiency of 11% is achieved without the need of light- or voltage soaking. This makes the superstrate configuration interesting again and it is shown how combinatorial material explorations in combination with the above mentioned progress will allow higher efficiencies in the future."
TOP20 publication at 31st EUPVSEC (September 2015)
PVcomB contribution selected for TOP20 at 31. EU PVSEC / Publication in "Progress in Photovoltaics"
A HZB joint publication from PVcomB and Institute for Silicon Photovoltaics has been rated as one of the best current work in the field of photovoltaics submitted to the 31. EUPVSEC. Dr. Onno Gabriel and co-authors were selected from more than 1,300 submissions as TOP 20 contribution of the conference with their publication "Crystalline Silicon on Glass: Interface Passivation and Its Impact on the Absorber Material Quality". The authors of the 20 highest scored abstracts of the EU PVSEC 2015 are invited to submit a paper for publication in the renowned scientific journal "Progress in Photovoltaics". The special edition will be available for free download for a year, a special feature of the not 'open access' publishing magazine
Gabriel and his colleagues investigate the influence of new industrial processes to produce thin crystalline silicon layers directly on glass. This preparation method is developed at HZB for several years and promises high material and energy savings. The at HZB measured efficiency of 12.1% is currently the world record for this solar cell technology.
"Crystalline Silicon on Glass: Interface passivation and its impact on the absorber material"
O. Gabriel1, T. Frijnts1, N. Preissler1, D. Amkreutz2, S. Calnan1, S. Ring1, B. Stannowski1, B. Rech2 & R. Schlatmann1,
1 PVcomB / Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany
2 Institute for Silicon Photovoltaics / Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany
"Thin crystalline silicon solar cells prepared directly on glass substrates by means of liquid-phase crystallization of the absorber utilize only a small fraction of the silicon material used by standard wafer-based silicon solar cells. The material consists of large crystal grains of up to square centimeter area and results in solar cells with open circuit voltages of 650 mV, which is comparable to results achieved with multi-crystalline silicon wafers. We give a brief status update and present new results on the electronic interface and bulk properties. The interrelation between surface passivation and additional hydrogen plasma passivation is investigated for p- and n-type absorbers with different doping concentrations. Internal quantum efficiency measurements from both sides on bifacial solar cells are used to extract the bulk diffusion length and surface recombination velocity. Finally, we compare various types of solar cell devices based on 10 µm thin crystalline silicon, where conversion efficiencies of 11 – 12 % were achieved with p- and n-type liquid-phase crystallized absorbers on glass."
Meet the PV experts! (September 2015)
From 14. to 18. September 2015 you can find our PV experts at the 31. EU PVSEC in Hamburg, Germany at the CHH Congress Center.
At the EU PVSEC, PVcomB will present its newest research results in oral and poster presentations. The works cover our three main research topics (1) thin-film (crystalline) silicon, (2) wafer-based HIT solar cells and (3) CIGS solar cell technolgy.
In addition, we would like to welcome you at our presentation booth in the joint booth of the Berlin-Brandenburg Energy Network - B8 (in hall 4). Together with researchers from the other institutes of HZB's energy research division we are looking forward to meet you and exchange information and experiences!
A poster-booklet (18 MB) including all HZB poster presentations of the conference is available here.
Oral presentations of PVcomB:
O. Gabriel, T. Frijnts, D. Amkreutz, S. Ring, S. Calnan, B. Stannowski, B. Rech & R. Schlatmann,
"Crystalline Silicon on Glass: Interface passivation and its impact on the absorber material quality"
H. Stange, S. Brunken, H. Hempel, H. Rodríguez-Alvarez, N. Schäfer, D. Greiner, A. Scheu, J. Lauche, C.A. Kaufmann, T. Unold, D. Abou-Ras & R. Mainz,
"Effect of Na-Presence during CuInSe2 Growth on Stacking Fault Density and Electronic Properties"
W. Calvet, B. Ümsür, A. Steigert, I. Lauermann, B. Chacko, V. Parvan, T. Olar, K. Prietzel, H. Allaf Navirian, S. Brunken, C.A. Kaufmann, D. Greiner, T. Unold & M.C. Lux-Steiner,
"Comparison of Surface Composition, Electronic Properties, and Solar Cell Performance of UHV-Transferred and Air Exposed CIGSe Thin Film Solar Cell Absorbers"
Poster presentations of PVcomB:
S. Ring, L. Mazzarella, P. Sonntag, S. Kirner, C. Schultz, U. Schmeißer, J. Haschke, L. Korte, B. Stannowski, B. Stegemann, R. Schlatmann,
"Emitter patterning for IBC-SHJ cells using laser hard mask writing and self-aligning"
C. Wolf, H. Rodriguez-Alvarez, S. S. Schmidt, D. Greiner, H.-W. Schock, C. A. Kaufmann, R. Schlatmann,
"Modifying the sulfur gradient in sequentially processed CIGSe absorber under atmospheric pressure using elemental chalcogenides"
M.D. Heinemann, R. Mainz, H. Rodriguez-Alvarez, D. Greiner, C.A. Kaufmann, T. Unold,
"Process and quality control of Cu(In,Ga)Se2 co-evaporation via white light reflectrometry"
H.F. Myers, P.v.d. Heuvel, P. Diepens, S.S. Schmidt, C. Wolf, H. Rodriguez-Alvarez, C.A. Kaufmann, R. Schlatmann, S. Villain, A. Weber, S. Bodnar, C. Guillou and C. Broussillou
"Improvement of Elemental Vapor Distribution Systems in CIGS Sulfo-Selenization Furnaces"
CIGS-solar cells Workshop: New opportunities for CIGS solar cells (May 2015)
Dynamic CIGS solar cell technology workshop gives rise to optimism: experts predict higher efficiencies and lean production technologies
More than 90 participants from industry and academia from Europe, Asia and USA exchanged latest results in the field of CIGS solar cells, during the “IW-CIGSTech 6” organised by PVcomB at HZB in Berlin-Adlershof from 29. to 30. April. They reported new, exciting results, ranging from record module efficiencies and significant module manufacturing simplification to solid scientific understanding of the underlying atomic-scale physics and chemistry. CIGS-thin film solar cells are based on compound semiconductors consisting of the elements Copper, Indium, Gallium and Selenium and Sulphur. They are the most efficient thin-film solar cell technology to date. PVcomB conducts research and technological improvement on CIGS solar cells, in close cooperation with industrial partners.
“We have seen very remarkable improvements in CIGS technology over the past year and many exciting new industrial and academic results were presented at the workshop”, says Rutger Schlatmann, head of the institute PVcomB at the HZB, explicitly mentioning following examples:
- A strong increase in world record cell efficiency to almost 22%, and a clear, scientifically based outlook towards 25% cells in the coming years.
- World record module efficiencies well above 16%.
- Restart of CIGS production capacity in Germany and upcoming remarkable expansion of production capacity worldwide.
- Production process simplifications (e.g. reduction of number of process steps).
- Very promising results in the field of wet processing, e.g. electrochemical deposition.
- Improved process control achieving a remarkable 98% process yield.
- Product development for very specific applications (large solar power plants with very low cost electrical power, aesthetic appearance and flexibility in design for BIPV).
“Summarizing the impressions of the workshop, there is a powerful community of CIGS technologists and academics. Many of them report rapid progress in development and there is an optimistic view on the successful growth of CIGS photovoltaics” Schlatmann concludes.
Masdar PV and Helmholtz-Zentrum Berlin partner to accelerate development of next generation thin film crystalline silicon PV technology (June2013)
MASDAR PV and PVcomB/HELMHOLTZ-ZENTRUM Berlin have strengthened their R&D partnership, focusing resources on development of next generation thin film Si technology. After successful cooperation in the development of Masdar PV´s first and second generation thin film silicon based solar cells, Masdar and HZB/PVcomB are now moving ahead to accelerate deployment of a new generation of thin film crystalline silicon based PV.
HZB has achieved the first milestone on this technology roadmap by succeeding in depositing a thin, crystalline 10μm layer of silicon on glass utilizing laser-crystallization. “Thin film crystalline silicon based PV can achieve high efficiency with low material cost”, explains Prof Bernd Rech. “Thus, it combines the advantages of incumbent, wafer-based crystalline silicon PV and thin film Si technology. Moreover, thin film crystalline silicon uses only abundantly available materials. We are confident to reach efficiencies comparable to wafer based crystalline silicon technology. On a long-term basis we are aiming for 20 % and beyond with thin film Si technology.”
Recent developments at HZB on crystalline thin film Si solar cells have triggered the interest of MASDAR PV to invest in related R&D. HZB researchers demonstrated a world record value for the open-circuit voltage of 582 mV for c-Si on glass. This break-through result, the excellent material properties of thin film crystalline silicon created by Liquid Phase Crystallization as well as promising processability of the material initiated the shift in R&D focus now announced by Masdar PV and HZB / PVcomB. “We expect that thin film crystalline silicon solar cells can achieve 14% efficiency cells in the short to mid-term”, says Prof. Rutger Schlatmann, leader of the technology transfer unit PVcomB at the HZB, “and we are confident that rapid technological progress is possible in this field”.
Masdar PV is aiming to transfer this technology into its existing production facilities and therefore deliver this new technology on modules up to full size (5.7m²).
“Investing in the R&D of this next generation technology of thin film silicon on glass to produce PV panels could enable us to better compete with existing crystalline PV producers who rely on economies of scale rather than significant technology improvements”, says Masdar PV’s MD Tushita Ranchan.
Solar modules at PVcomB are on world-record level (May 2013)
At PVcomB we succeeded to push the conversion efficiency of a-Si/µc-Si tandem solar cells towards world-record level: With a 1 cm² solar cell a stabilized efficiency of 12.1 % was reached, and for a 10 x 10 cm² lab module the same process yielded a stabilized aperture-area efficiency of 11.6 %, both after 1000h of light soaking at 50°C and 1 sun.
These results were obtained after carefully optimizing the PECVD deposition processes of the intrinsic silicon and the doped silicon-oxide based layers. As front TCO highly transparent thermally-annealed sputtered ZnO:Al was used. A textured AR foil from Solarexcel (DSM) was applied on the front glass.
Modules with 30 x 30 cm² currently exhibiting an efficiency of 11.7 % (initial) and 10 % (stable).
PVcomB boosts CIGS development by investing in new generation active selenization system (January 2013)
The Competence Centre Thin-Film- and Nanotechnology for Photovoltaics Berlin, PVcomB, ordered active selenization system from Smit Ovens BV. The R&D system ordered offers the same concept as mass production systems and actively support selenium and sulfur transport to the substrates during the RTP process. This will accelerate development of highly efficient CIGS technology at PVcomB.
Smit Ovens’s newly developed active selenization systems get recognized by PVcomB. PVcomB offering process services throughout the CIS and CIGS industry. The investment will accelerate their development roadmap to high efficient cells.
“Experiments show that vapor phase reactors allow new pathways into highly efficient CIGS cell development.” States Dr. Niklas Papathanasiou, manager CIGS development at PVcomB. “The active reactor design is the industrialized solution for our experiments”. After careful market evaluation PVcomB decided to contract Smit Ovens for the supply of a flexible R&D system capable of running 300x300mm substrates. The system’s active reactor design is state of the art thermal technology and offers a high level of repeatability and controllability needed in reliable mass production environment.
“The design of this R&D system is identical to the large area & high throughput systems” States Wiro Zijlmans, CEO at Smit Ovens BV. ”This allows for a fast and reliable scale up to mass production on the basis of processes developed by PVcomB."