Approved! The EU INFINITE-CELL project
A large EU-sponsored research project on tandem solar cells in which HZB is participating begins in November 2017. The goal is to combine thin-film semiconductors made of silicon and kesterites into especially cost-effective tandem cells having efficiencies of over 20 per cent. Several large research institutions from Europe, Morocco, the Republic of South Africa, and Belarus will be working on the project, as well as two partners from industry.
“We not only have detailed experience with kesterite thin films, but also a wide spectrum of analytical methods at our disposal to characterise absorber materials very thoroughly”, explains Prof. Susan Schorr. The FUNDACIO INSTITUT DE RECERCA DE L’ENERGIA DE CATALUNYA (IREC), Spain – a long-term collaborating partner of the HZB, is coordinating the entire project. The project begins with a kick-off workshop in Brussels in November 2017.
Ambitious Goals
Goals of the project are quite concrete: the kesterite solar cells should reach an efficiency level of more than 14 per cent (currently they are just below 12%), while thin-film silicon cells made from recycled material should reach an efficiency level of over 16 per cent. Reaching more than 20 % is feasible because silicon uses a different energy region of light to generate electricity than kesterite does. When you combine both materials into one tandem solar cell, where you stack them upon one another or even grow one on the other, it enables a considerably larger proportion of solar energy to be converted into electrical energy. These kinds of especially efficient and also cost-effective solar modules might be employed in cladding, and on roof surfaces – for both buildings and vehicles – to generate power locally.
Why Kesterites?
“Kesterites are a very interesting class of materials”, emphasises Schorr. For even though other absorber materials like copper-indium-gallium-sulphides (CIGS) or metal-organic perovskite semiconductors are able to attain considerably higher efficiency levels today, kesterites trump them with two big advantages: kesterites consist of very abundant elements, and they are non-toxic.
Exchange between partner institutions
The project INFINITECELL, which is a Research and Innovation Staff Exchange (RISE) type funding, has a duration of four years. It is part of the Marie Skłodowska-Curie Actions Programme funded by the EU within Horizon 2020. This enables scientists over the coming years to travel to partner institutions in order to exchange experience, skills, and insights. The joint research is set out in a detailed Secondment Plan.
- Battery research: visualisation of aging processes operandoLithium button cells with electrodes made of nickel-manganese-cobalt oxides (NMC) are very powerful. Unfortunately, their capacity decreases over time. Now, for the first time, a team has used a non-destructive method to observe how the elemental composition of the individual layers in a button cell changes during charging cycles. The study, now published in the journal Small, involved teams from the Physikalisch-Technische Bundesanstalt (PTB), the University of Münster, researchers from the SyncLab research group at HZB and the BLiX laboratory at the Technical University of Berlin. Measurements were carried out in the BLiX laboratory and at the BESSY II synchrotron radiation source.
- New instrument at BESSY II: The OÆSE endstation in EMILA new instrument is now available at BESSY II for investigating catalyst materials, battery electrodes and other energy devices under operating conditions: the Operando Absorption and Emission Spectroscopy on EMIL (OÆSE) endstation in the Energy Materials In-situ Laboratory Berlin (EMIL). A team led by Raul Garcia-Diez and Marcus Bär showcases the instrument’s capabilities via a proof-of-concept study on electrodeposited copper.
- Green hydrogen: A cage structured material transforms into a performant catalystClathrates are characterised by a complex cage structure that provides space for guest ions too. Now, for the first time, a team has investigated the suitability of clathrates as catalysts for electrolytic hydrogen production with impressive results: the clathrate sample was even more efficient and robust than currently used nickel-based catalysts. They also found a reason for this enhanced performance. Measurements at BESSY II showed that the clathrates undergo structural changes during the catalytic reaction: the three-dimensional cage structure decays into ultra-thin nanosheets that allow maximum contact with active catalytic centres. The study has been published in the journal ‘Angewandte Chemie’.