Nicolas Blondiaux

For the current PV production about 2000 tons of silver are consumed per year, 10% of the entire world annual silver supply. The PV production is expected to grow significantly in the next decades in order to enable the energy transition to 100% renewables. Annual production volumes in the terawatt range are predicted already for 2030 and this may lead to higher silver price and put more pressure on the industry to replace silver by copper. Within the Ameliz project several patterning approaches for copper electrodeposition on heterojunction cells are developed: firstly, patterning by printing a metal seed grid with a dielectric layer as plating mask and secondly masking by a monolayer of self-assembling molecules. These molecules consist of a phosphonic acid group and a hydrocarbon chain. They are bonded to the ITO surface and form a monolayer of well-ordered, densely packed hydrophobic chains, which protects the ITO surface against plating solutions. Furthermore, methods for selective formation of a copper seed layer by electrografting and for improved adhesion by ITO reduction are being investigated.

We report on the fabrication of sub-micro and nanostructured steel mold inserts for the replication of nanostructured immunoassay biochips. Planar and microstructured stainless steel inserts were textured at the sub-micron and nanoscale by combining nanosphere lithography and electrochemical etching. This allowed the fabrication of structures with lateral dimensions of hundreds of nanometers and aspect ratios of up to 1:2. Nanostructured plastic parts were produced by means of hot embossing and injection molding. Surface nanostructuring was used to control wettability and increase the sensitivity of an immunoassay.

We demonstrate self-patterned insulating nanoparticle layers to define local electrical interconnects in thin-film electronic devices. We show this with thin-film silicon tandem solar cells, where we introduce between the two component cells a solution-processed SiO₂ nanoparticle layer with local openings to allow for charge transport. Because of its low refractive index, high transparency, and smooth surface, the SiO₂ nanoparticle layer acts as an excellent intermediate reflector allowing for efficient light management.