Biomimetic nano-technology is not a term often heard in the context of renewable energy – except in the rapidly developing field of dye-sensitised photovoltaics.

Image: the stuff of future flexible cells, ruthenium dye in preparation in Dyesol labs

 Dye Solar Cells (DSCs) are the most advanced of the new generation of ‘non-silicon’ solar cells that are rapidly emerging from research efforts around the world into commercial solar products. DSCs are made with cheap materials, can be easily manufactured as flexible products and have very useful performance attributes such as being able to generate electricity in very low light long after silicon cells have stopped.

As a result, in real world conditions, such as in tropical climates and smoggy cities, DSC is capable of outperforming even high quality silicon products on the basis of annual kWh produced per square metre of product.

DSC mimics nature in the sense that it uses a dye and a two step process for generating electrons, very similar to the process in plants where that green dye called chlorophyll captures photons and produce sugars and oxygen.

In DSC a porous layer of nano-particles of titania dioxide – the common white stuff used in toothpaste and white paint - is sandwiched with quite rare manufactured dyes, such as ruthenium dye. The atom thin layer of dye absorbed onto a layer of titania dioxide causes the titania to become photosensitized. Light striking the dye excites electrons which are absorbed by the titania. This process generates an electric current many times stronger than that found in natural photosynthesis

This handy sub-atomic event is turned into a photovoltaic cell when the dye-doped titania is laminated between an electrolyte and a conducting base, something that is starting to happen in a great number of forms.

G24i, (http://www.g24i.com ) a Welsh based DSC manufacturing company has just announced an order for small flexible DSC has been sold to Kenya where they will be used to charge mobile phone batteries. Flexible photovoltaic material raises lots of possibilities for trickle charging consumer electronics and integration into clothes and bags.

While g24i is the first company into the market with a novel consumer product using DSC, the company that really ‘owns’ this space is Dyesol Ltd (or homepage www.dyesol.com ), a company listed on the Australian stock exchange.

Dyesol owns numerous strategic patents, has extensive practical expertise in the DSC field and has a novel business model for profiting from the explosive growth in solar technology in general, and DSC in particular.

Dyesol specializes in the manufacture of the dyes and materials that go into manufacturing DSC, and produces a range of components and equipment used in DSC labs for manufacture, testing and quality control of cells.

But rather than attempt to commercialise DSC products on their own, Dyesol sells the high quality DSC materials they manufacture to corporate and academic research labs around the world and engages in consulting research. They also partner with selected market leaders in particular fields and work to develop  DSC photovoltaic products for that company’s existing distribution channels.

In December 2006 Dyesol embarked on something akin to the holy grail of solar power -  a collaborative program with the worlds fifth largest producer of rolled steel products, the UK based giant Corus. The project is working to demonstrate a continuous rolled steel coating line to produce a DSC laminated photovoltaic steel roofing sheets. Corus believes this will provide the most cost effective path to market for photovoltaic roofing and wall cladding systems. At time of writing that project had passed all the technical milestones of demonstrating the laminating process and was working on the design of the coating line itself.

Dyesol has also been working with the Australian Defence Science Technology Organisation to demonstrate light and flexible cells for portable power systems. In mid-November that project culminated in the demonstration to DSTO of three different designs for light weight, waterproof, dappled camouflague flexible cells that are intended to charge equipment in the field and could possibly be used in aviation and ocean environments. All of which has implications for being able to produce long life DSC for a wide range of products.

Building on its comprehensive IP portfolio Dyesol are also engaged in cutting edge proprietary research that could dramatically reduce the costs of DSC materials.

“The next cornerstone technology that we believe will accelerate the widespread commercialization of DSC products, involves continuous production processes,” Sylvia Tulloch, Dyesol’s Managing Director said.  “DSC first became recognized in the last decade because of the potential of nano-chemistry to slash the cost of production of solar cells. We are now pursuing another such disruptive and cost reducing production process.”

Presently the dyes, gels, pastes and other materials that make up DSC are produced in batch processes. Some of them are very expensive. Dyesol sells some of the essential nanochemical ingredients of DSC research for thousands of dollars per gram. The highly controlled and proven batch processes involved have been developed over many years and provide tremendous quality control on the performance characteristics of the nano-chemical products. However they are also an area of significant cost.

“Continuous production processes that deliver consistently high quality product has the potential to drastically reduce the cost of DSC materials used in the deposition of multilayered DSC devices,” Mrs Tulloch said. “The intense reaction conditions created in continuous production have a number of potentially significant advantages for manufacture of DSC materials, as long as they can be controlled.”

Dyesol is working closely with the University of Western Australia’s Centre for Strategic Nano-fabrication, the Queensland University of Technology and the Swiss Federal Institute to realise this next revolution in DSC even while the first one is still unfolding.  

With industrial and research partnerships already underway in Thailand, Italy, Germany, the UK, Japan, China, Switzerland, Turkey and Australia the Dyesol business model is rapidly promoting the spread of the art and science of DSC.  At a recent international conference in Switzerland, the 2^nd DSC Industrialisation Conference, sponsored by Dyesol, more than 200 delegates from 25 countries were presented with the results of intense research efforts from around the world aimed at getting DSC into production.

One outstanding paper examined fundamental work under way by a venture between Yokohama University and Peccel Technologies aimed at perfecting roll to roll production of plastic DSC materials. Prototype forms of these PDSC have already been manufactured achieving between 2% and 4% conversion efficiency in diffuse light. 

The Danish Technological Institute presented their work on long lived, large, light filtering DSC cells for use in building facades. In this BIPV application all of the competitive advantages of DSC potentially come together, ie  enhanced energy production in low, filtered and indirect light conditions and low cost of DSC on a square metre basis. DSC integrated building products will also have significant architectural virtues that silcon based BIPV do not. This includes being able to be manufactured in various colors, be based on glass - the most popular cladding material for large commercial buildings - and of course the desirable quality of semi-transparency, or rather selective transparency, allowing in only preferred wavelengths and stopping or generating electron flows from other wavelengths.

While investigating robust sealant chemistry and other mechanical aspects of large cell production, the Danish team is also in the middle of transferring their laboratory scale DSC cell manufacture to a fully automated screen printing line, with partner Mekoprint A/S, in preparation for demonstrating commercial scale production techniques of glass based facade materials.

The Institute of Plasma Physics at the Chinese Academy of Sciences reported on their DSC project which, by 2004 had reliably fabricated 450mm by 800mm cells and constructed a 500W demonstration panel that delivered greater than 5% conversion efficiency outdoors. They announced that a Chinese project for DSC industrialisation had been launched in the last year by the Chinese Ministry for Science and Technology with the singular objective of pushing DSC to commercial release in China.

For their part Dyesol took the opportunity to launch a completely new range of DSC laboratory and manufacturing equipment, further reinforcing their position as one of Australia’s very few home grown 100% solar energy exporters.

To service the increasing demands of their existing corporate and institutional customers, like Corus, Sony and Samsung, and to supply the rapidly growing ranks of new buyers, Dyesol is advancing plans for construction of new production facilities simultaneously in both Australia and the UK. By 2009 Dyesol plans to have the capacity to manufacture their trademark, high quality nanochemicals, pastes, dyes and laboratory equipment to supply a rapidly growing part of what will by then be a $50 billion a year global solar industry.

Michael McCann is a Director of Canberra-based Energy Strategies Pty Ltd, www.energystrategies.com.au  a company that has been involved in promoting sustainable energy policy, technology and practice since 1991.