Midsummer AB


Midsummer AB

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Bras P.,Midsummer AB | Bras P.,Uppsala University | Frisk C.,Uppsala University | Tempez A.,HORIBA Jobin Yvon S.A.S. | And 2 more authors.
Thin Solid Films | Year: 2017

Cadmium-free Cu(In,Ga)Se2 (CIGS) solar cells are fabricated on stainless steel substrate using an industrial, in-line vacuum, all sputtering process. The absorber layer is deposited from compound CIGS targets and crystallized simultaneously by high temperature processing. In-depth compositional and structural characterization of the chalcopyrite material is conducted and a Solar Cell Capacitance Simulator (SCAPS) model for the complete device is set-up. Ga-grading of the absorber through the successive use of different CIGS target compositions and resulting in solar cell performance enhancement is shown. At the research and development scale, efficiency values of 15.1% and 13.2% are reported for 1 cm2 and 225 cm2 total area solar cells, respectively. Successful transfer to production is also demonstrated. A series of a hundred 225 cm2 solar cells produced following an optimized process including the Ga grading studied in the present contribution average at 14.8% total area efficiency. © 2016 Elsevier B.V.

Agency: European Commission | Branch: H2020 | Program: RIA | Phase: LCE-01-2014 | Award Amount: 3.25M | Year: 2015

The aim of this proposal is to develop wide band gap thin film solar cells based on kesterite absorbers for future application in high efficiency and low cost tandem PV devices. The SWInG working group will focus both on the development of the processes for the synthesis of such solar cells based on the Cu2ZnXY4 (with X=Sn, Si and Y= S, Se) compounds and on the understanding of the physical and electrical properties of the high band gap absorber in order to reach high conversion efficiency. The key research challenges will be: developing up-scalable processes for the synthesis of the absorbers; defining the specifications for high quality wide band gap absorbers as well as suitable back contact and buffer/window layers; assessing the potential of this technology for PV applications. The wide band gap thin films solar cells developed in this project are expected to reach a stable efficiency of 15 % on a laboratory scale and 12 % for a mini-module prototype. The publications of specifications for the synthesis of high quality Cu2ZnXY4 absorber as well as suitable back/front contact are expected. The lead users will be PV modules manufacturers that work so far with thin films technologies, as well as the companies that design and produce the machines for the synthesis of such devices. The results will be disseminated and communicated to the European PV industries and the scientific community. The intensive exchange of researchers between the partners during the project will also lead to an enhanced European collaboration in the research field of thin film solar cells.

Agency: European Commission | Branch: H2020 | Program: IA | Phase: NMBP-17-2016 | Award Amount: 5.10M | Year: 2016

Advanced aRchitectures for ultra-thin high-efficiency CIGS solar cells with high Manufacturability (ARCIGS-M) This projects goal is advanced materials and nanotechnologies for novel CIGS PV device architectures with efficiencies 23.0 %, thus beyond that of the current state-of-the-art technologies. The technology targets the BIPV sector and enables several innovative solutions for BIPV. The novel functional materials and material combinations are (1) surface functionalized steel substrates, (2) nano-structuring strategies for optical management of rear contact layers, (3) passivation layers with nano-sized point openings, and (4) ultra-thin CIGS thin film absorber layers. The concepts will be developed and established in production viable equipment. Additionally, this new design will also increase the systems lifetime and materials resource efficiency, mainly due to the use of ultra-thin CIGS layers (less In and Ga), and barrier and passivation layers that hinder alkali metal movement. Hence, this project will lead to enhanced performance, but also yield and stability, while maintaining manufacturability. The consortium includes SMEs and industrial partners positioned throughout the complete solar module manufacturing value chain. Their roles will be to develop and commercialize new equipment, products and/or services. The consortium already pioneered the proposed advanced material solutions up to technology readiness level (TRL) 4, and this project targets to bring these innovative concepts to TRL 6 in a low-cost demonstrator. The aim is to develop and validate innovative, economic and sustainable BIPV applications, as a near future high value market for the European PV industries. An exploitation strategy, developed with the support of TTO (www.tto.dk), identifying BIPV as the most promising market has been used to validate the choice of technologies and will be further developed during the course of the project.

Agency: European Commission | Branch: H2020 | Program: RIA | Phase: NMBP-03-2016 | Award Amount: 6.22M | Year: 2017

STARCELL proposes the substitution of CRMs in thin film PV by the development and demonstration of a cost effective solution based on kesterite CZTS (Cu2ZnSn(S,Se)4) materials. Kesterites are only formed by elements abundant in the earth crust with low toxicity offering a secure supply chain and minimizing recycling costs and risks, and are compatible with massive sustainable deployment of electricity production at TeraWatt levels. Optimisation of the kesterite bulk properties together with redesign and optimization of the device interfaces and the cell architecture will be developed for the achievement of a challenging increase in the device efficiency up to 18% at cell level and targeting 16% efficiency at mini-module level, in line with the efficiency targets established at the SET Plan for 2020. These efficiencies will allow initiating the transfer of kesterite based processes to pre-industrial stages. These innovations will give to STARCELL the opportunity to demonstrate CRM free thin film PV devices with manufacturing costs 0.30 /Wp, making first detailed studies on the stability and durability of the kesterite devices under accelerated test analysis conditions and developing suitable recycling processes for efficient re-use of material waste. The project will join for the first time the 3 leading research teams that have achieved the highest efficiencies for kesterite in Europe (EMPA, IMRA and IREC) together with the group of the world record holder David Mitzi (Duke University) and NREL (a reference research centre in renewable energies worldwide) in USA, and AIST (the most renewed Japanese research centre in Energy and Environment) in Japan. These groups have during the last years specialised in different aspects of the solar cell optimisation and build the forefront of kesterite research. The synergies of their joined efforts will allow raising the efficiency of kesterite solar cells and mini-modules to values never attained for this technology.

The Swedish company Midsummer AB has developed an all-sputtering process and equipment for CIGS solar cells. The company was founded in 2004 by people from the optical disc and flat panel display industry. Most CIGS solar cells are made on large glass substrates, another option is to make the solar cells with a roll-to-roll process on a flexible stainless steel substrate. Midsummer has chosen a third approach, by adopting the founders experience from the low cost optical disc industry. Instead of increasing the productivity by increasing the substrate size, they decided to design a machine and process that produces many small substrates with fast pace. Such a machine can be very compact and the productivity is achieved by using 25 small sputter chambers. Large scale production of solar cells can them be achieved by adding many small production systems, exactly as was in the case for optical discs, that eventually lead to an annual production capacity of 35 billion CDs and DVDs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bras P.,Midsummer AB | Bras P.,Uppsala University | Sterner J.,Midsummer AB | Platzer-Bjorkman C.,Uppsala University
Thin Solid Films | Year: 2015

With a theoretical efficiency around 30% and an optimized band gap for sunlight absorption, Cu2ZnSnS4(CZTS) is a promising, earth-abundant, material for thin film solar cells. Sputtering CZTS from a quaternary compound target is a quick and potentially industrial-scaled process that has not been investigated deeply yet. Our approach is based on an in-line vacuum system for the complete device. CZTS is sputtered from a compound target on a sodium molybdate (MoNa) pre-sputtered stainless steel substrate, and then annealed in high-pressure H2S atmosphere. A 1 μm thick absorber is obtained within 7 minute sputtering. Top layers are then deposited, without vacuum breaking. The effects of different annealing temperatures on the absorber morphology and composition are investigated. It is observed that recrystallization already occurs at 420 °C and that crystallinity improves with increasing temperature up to 550 °C. However, micro-sphere formation underneath the film degrades the corresponding solar cell performance dramatically above 510 °C. It is shown that sodium is needed in order to enhance recrystallization of CZTS but the MoNa layer thickness seems not to be a critical parameter. Scanning electron microscopy, X-ray diffraction, X-ray fluorescence and current-voltage measurement were used to characterize the samples. © 2014 Elsevier B.V.

Bras P.,Midsummer AB | Bras P.,Uppsala University | Mauvy L.,Midsummer AB | Sterner J.,Midsummer AB | Platzer-Bjorkman C.,Uppsala University
2015 IEEE 42nd Photovoltaic Specialist Conference, PVSC 2015 | Year: 2015

Cu2ZnSnS4 solar cells are fabricated following an all-sputtering in line vacuum approach. 6-inch semi-square stainless steel substrates are used. A compositional and structural study of the absorber layer is conducted before and after annealing to assess the uniformity of both the sputtering and the annealing process. It is found that while the precursors are uniform both in morphology and composition, the annealing process introduces differences in grain size and metal content depending on the area considered on the 6-inch substrate. The corresponding solar cell is further divided into 184 small cells of 1cm2 to check the performance distribution across the device. Current-voltage characteristics and solar cell parameters are extracted. Natural convection inside the annealing chamber is suggested to affect significantly the heat distribution and a strong correlation between device performance and local temperature can be identified. © 2015 IEEE.

Bras P.,Midsummer AB | Bras P.,Uppsala University | Sterner J.,Midsummer AB | Platzer-Bjorkman C.,Uppsala University
Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films | Year: 2015

Blister formation in Cu2ZnSnS4 (CZTS) thin films sputtered from a quaternary compound target is investigated. While the thin film structure, composition, and substrate material are not correlated to the blister formation, a strong link between sputtering gas entrapment, in this case argon, and blistering effect is found. It is shown that argon is trapped in the film during sputtering and migrates to locally form blisters during the high temperature annealing. Blister formation in CZTS absorbers is detrimental for thin film solar cell fabrication causing partial peeling of the absorber layer and potential shunt paths in the complete device. Reduced sputtering gas entrapment, and blister formation, is seen for higher sputtering pressure, higher substrate temperature, and change of sputtering gas to larger atoms. This is all in accordance with previous publications on blister formation caused by sputtering gas entrapment in other materials. © 2015 American Vacuum Society.

Bras P.,Midsummer AB | Bras P.,Uppsala University | Sterner J.,Midsummer AB
2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014 | Year: 2014

Sputtering Cu2ZnSnS4 absorbers from a quaternary compound target has not been deeply investigated yet although it is a fast process that could be adapted to an industrial scale. We propose a new approach based on an in-line vacuum system for the complete device. The effects of H2S annealing parameters as well as buffer type are investigated. We present a 4.2% efficiency device based on stainless steel substrate. © 2014 IEEE.

Midsummer Ab | Date: 2012-12-14

There is provided a method for providing selenium dioxide and a copper indium gallium residue from a material comprising a compound of formula (I) CuIn_(x)Ga_((1-x))Se_(2 )(I), wherein x has a value from 0.01 to 0.99, said method comprises the steps of: a) heating the material comprising the compound of formula (I) to at least 500 C., b) contacting the material with a gas flow comprising oxygen, and d) collecting the formed products. The method may be used in recycling in the field of solar cell technology.

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