Printable, flexible solar cells that could dramatically decrease the cost of renewable energy have been developed by PhD student Brandon MacDonald in collaboration with his colleagues from CSIRO’s Future Manufacturing Flagship and the University of Melbourne’s Bio21 Institute.
Australian researchers have developed solar panels which can be painted or printed directly onto a surface. With help from the CSIRO, University of Melbourne PhD student Brandon MacDonald has produced solar cells so small they can be suspended in liquid, such as ink or paint. MacDonald hopes the new technology will be two to three times cheaper than solar cells currently on the market, Macdonald says he expects the cells to hit the market within 5 years. These solar panels will be made of nano-crystals with a diameter of just a few millionths of a millimetre. MacDonald says they will use just 1 per cent of the materials needed to make traditional solar panels.
“Using nano-crystal inks, they can be manufactured in a continuous manner, which increases throughput and should make the cells much cheaper to produce, we can then apply this ink onto a surface, so this could be glass or plastics or metals”
Nano-crystals, also known as quantum dots, are semiconducting particles with a diameter of a few millionths of a millimetre. Because of their extremely small size they can remain suspended in a solution. This solution can then be deposited onto a variety of materials, including flexible plastics or metal foils. It is then dried to form a thin film. Macdonald discovered that by depositing multiple layers of nano-crystals they can fill in any defects formed during the drying process.
“What we could do is actually integrate these into the building as it’s being made, so you can imagine solar windows, or having it actually be part of the roofing material“
The nanocrystals consist of a semiconducting material called cadmium telluride, which is a very strong absorber of light. This means that the resulting cells can be made very thin. The technology is not limited to solar cells. It can also be used to make printable versions of other electronic devices, such as light emitting diodes, lasers or transistors.
“The total amount of material used in these cells is about 1% of what you would use for a typical silicon solar cell. Even compared to other types of cadmium telluride cells ours are much thinner, using approximately one-tenth as much material. The problem with conventional solar cells, which are based on silicone and have been around for 60 years, is that they are quite efficient at converting sunlight to energy. In terms of making them it’s a fairly costly and time-consuming process and so at the moment solar energy is more expensive than, say, coal or fossil fuels. With these inks, and eventually trying to print the cells on a large scale, we hope that we’ll make it so that this technology is cost-competitive with traditional energy sources” says Macdonald.
An Australian-based solar innovator - Dyesol – have already taken a huge step toward the large scale marketing of a similar product. Dyesol has struck a deal with steel giant Tata Steel to develop building products, such as steel girders and roofing panels, with solar panels embedded in the surface. Dyesol founder, Sylvia Tulloch, says the product should be ready to go in two years.
“I think a third generation solar, where we talk about processes that enable us to integrate solar layers into all sorts of everyday products and particularly into building products – so roofs, or walls or windows that have layers on them that generate electricity” said Dyesol’s Silvia Tulloch.
The technology, known as Dye Solar Cell – DSC or Dye Densitised Sollar Cell – DSSC – described by Dyosel as ‘artificial photosynthesis’ using an electrolyte, a layer of titania, a pigment used in white paints and tooth paste-and ruthenium dye deposited on glass, metal or polymer substrates. Light striking the dye excites electrons which are absorbed by the titania to become an electric current many times stronger than that found in natural photosynthesis in plants. Compared to conventional silicon based photovoltaic technology, Dyesol’s technology has lower cost and embodied energy in manufacture, it produces electricity more efficiently even in low light conditions and can be directly incorporated into buildings by replacing conventional glass panels or metal sheets rather than taking up roof or extra land area.
These innovations are of course a logical step in building materials, almost a natural evolution. The teaming of technology with base manufacturing is prime in our move forward on sustainable, affordable solar. Peter Strikwerda, Managing Director of Tata Steel Colors, said “This project forms a key part of the Tata Steel strategy to develop a new range of functional coated steel products based on renewable energy for use on the roofs and walls of buildings. The project has met the objectives originally set for this phase to determine the photovoltaic cell architecture on steel, the roof component designs, the manufacturing processes and the raw materials requirements”
Brandon MacDonald - Brandon.Macdonald@csiro.au
Dyesol - Phone: +61 (0)2 6299 1592 - Fax: +61 (0)2 6299 1698
Picture via Anthony Chesman