Non-stick coating offers efficient way to pattern metals

Chemists at the University of Warwick in the UK have discovered an innovative way to pattern metals, which could make the next generation of solar panels cheaper and more sustainable.

Silver and copper are the most widely used electrical conductors in modern electronics and solar cells. However, conventional methods of patterning these metals to make desired networks of conducting lines involve either selectively removing metal from a film by etching with harmful chemicals or printing with costly metal inks.

Chemists at the University of Warwick, led by Ross Hatton, have now developed a new method for patterning these metals that is likely to prove much more sustainable and cheaper for large scale production. There is no metal waste or use of toxic chemicals, and the method is compatible with continuous roll-to-roll processing. The chemists report the method in a paper in Materials Horizons.

The method is based on the chemists’ discovery that silver and copper do not condense onto extremely thin films of highly fluorinated organic compounds, similar to those used for non-stick coatings on cooking pans, when the metal is deposited by simple thermal evaporation. The organofluorine layer needs only be 10 billionths of a meter thick to be effective, meaning only tiny amounts are needed.

This unconventional approach also leaves the metal surface uncontaminated, which Hatton believes will be particularly important for next generation sensors. These often require uncontaminated patterned films of metals as platforms onto which sensing molecules can be attached.

But the most important use for this method could be in solar cells, where there is a need for producing color-tuneable, flexible and light-weight solar cells at low cost. This is particularly the case for applications where conventional, rigid silicon solar cells are unsuitable, such as in electric cars and semi-transparent solar cells for buildings.

Solar cells based on thin films of organic perovskite or nano-crystal semiconductors all have potential to meet this need, but they all require a low cost, flexible transparent electrode. Hatton and his team have used their novel method to fabricate semi-transparent organic solar cells in which the top silver electrode is patterned with millions of tiny apertures per square centimeter. This could not be done by any other scalable means directly on top of an organic electronic device.

"This innovation enables us to realize the dream of truly flexible, transparent electrodes matched to needs of the emerging generation of thin film solar cells, as well as having numerous other potential applications ranging from sensors to low-emissivity glass," says Hatton.

This story is adapted from material from the University of Warwick, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.