HZB receives financial support for improving the manufacturing process for CIGS solar cells
Sebastian Schmidt demonstrating one of the CIGS-Modules. © HZB
The Helmholtz-Zentrum Berlin (HZB) has pulled in a large project for further improving the manufacturing process for CIGS thin-film solar cells together with partners in Germany and from 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.
- CIGS-perovskite tandem cell achieves record efficiency of 25.5 %A Berlin-based team from HZB and Center for the Science of Materials Berlin (CSMB) at the Humboldt-Universität zu Berlin has set a new record for a tandem solar cell. Using a combination of a CIGS semiconductor layer and perovskite, along with several optimised intermediate layers, they were able to convert 25.5% of sunlight into electrical energy. The previous record for this combination of materials and this size of cell stood at 24.6%. The new record has been certified and is visible in the prestigious Solar Cell Efficiency Tables (the "Green Tables"), which serve as the definitive ledger for the global photovoltaic community.
- Disorder creates new properties in compound semiconductorsAn international research team has demonstrated that the intrinsic disorder of the compound semiconductor CuInSnS₄ can be exploited to influence its optical properties. While the atomic vibrations also sense the local disorder, their response is averaged over many different local environments and therefore appear isotropic, as expected for a cubic crystal. In contrast, the optical excitations, known as excitons, are much more sensitive to the local arrangement of atoms. Surprisingly, they show a direction-dependent optical response even though the average crystal structure is cubic. These findings shed new light on the relationship between disorder and material properties, opening up new options for targeted 'disorder engineering' in optoelectronic and photocatalytic devices.
- Perovskite solar cells: Predictions of long-term stabilityReliable statements about the long-term stability of perovskite solar cells are still difficult to make. However, a new study by Dr Carolin Ulbrich’s team, published in the renowned journal Joule, highlights which methods are useful for this purpose and identifies areas where further research is needed.