Winchester, UK - To support fundamental research into the fabrication of hybrid solar cells Munich-based Ludwig-Maximilians University (LMU) has ordered an advanced sputtering tool from Surrey NanoSystems of Newhaven, UK.

The tool will be used to develop production techniques that utilise precisely ordered nanowire structures as templates for organic material. Compared with conventional silicon-based solar energy systems the new generation of hybrid solar cells has the potential to lower costs. By building arrays of organic solar cells on a low-resistance nanowire interconnection substrate, LMU expects to increase the efficiency of the energy conversion process.

"Hybrid solar cells - mixing organic with inorganic materials - have currently relatively low efficiencies (below six percent), mainly because of inefficient charge separation and collection. With our nanostructures we hope to overcome this problem and improve the efficiencies significantly. Hopefully in the long term this improvement will be by a factor of about two which would make these structures interesting for low cost solar cells," explained Professor Lukas Schmidt-Mende of the LMU Department of Physics and Centre for NanoScience.

The tool will be used by researchers in LMU's Department of Physics and Centre for NanoScience. The equipment is a configuration of Surrey NanoSystems' Gamma tool, an advanced PVD (plasma vapour deposition) sputtering system that is optimised for both performance and versatility of use, and is widely used in R&D and pilot production applications. The tool's high vacuum capability of 5 x 10-9 Torr, which is as much as two orders of magnitude higher than some other commercially available sputtering systems, was a key selection factor as it provides a pure environment to aid uniform film deposition - a critical factor for the techniques being developed by LMU.

Some further special facilities for the tool have also been specified by LMU to help produce uniform aluminium films, which will then be processed to form highly ordered porous alumina membranes on various substrates - one of the fabrication approaches under research. Further support for up to four sputtering target materials will also provide the research team with the flexibility to deposit barrier layers and other inter-layer films that might be required to ensure good adherence of the solar cell's active structures.

"Structural precision is a key element of making efficient, low-loss hybrid solar cells, and LMU's research will focus heavily on this aspect," said Professor Schmidt-Mende. "The high quality of film deposition that the Gamma tool can achieve gives us a very versatile platform to support our studies."