As solar energy becomes more prevalent in the electrical industry, Dimi Kyriakou discovers that Australian researchers have begun developing an alternative solar cell that is thin, flexible and uses a tiny fraction of the materials in conventional silicon cells.

If you walk into any ‘clean energy’-themed expo these days, you’re bound to face an endless array of solar panels that, quite honestly, all seem to look the same after a while.

Yet one research team in Australia has started to think outside the square and target the heart of the solar system itself: the solar cell. And it’s a development that could bode well for electricians completing solar installations in the future.

Nanocrystal solar cells are printable, lightweight cells that could dramatically decrease the cost of renewable energy. This patented technology is based on inks containing tiny, semiconducting nanocrystals, which can be printed directly onto a variety of surfaces including glass, certain plastics and metal foils.

The project was 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.

“Nanocrystal solar cells convert light to electricity the same way as conventional silicon solar cells. The difference between these two technologies lies in how the solar cells are produced,” he explains.

Although conventional solar cells have existed for nearly 60 years, they sport a higher cost than conventional energy sources such as gas and coal. These nanocrystal cells aim to decrease the cost of solar energy to a point where it is a cheaper energy option.

“Silicon cells require a complex fabrication process which includes extremely high temperatures and long processing times. In contrast, nanocrystal solar cells are manufactured using what can be described as ‘solar inks’.

“These inks can be deposited by methods such as printing or spray-coating, making it possible to produce efficient solar cells using very little material, cost or energy.”

Nanocrystals, 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 material and dried to form a film. Brandon and his colleagues discovered that by depositing multiple layers of nanocrystals, they can fill in any defects formed during the drying process and produce a densely packed, uniform film.

“By depositing the cells on a surface such as stainless steel, it will be possible to have the cells integrated directly into building materials rather than as an add-on after building construction has finished,” he says.

“A typical nanocrystal cell requires only 1% as much material as a standard silicon cell and the material used in these cells, cadmium telluride (CdTe), is a much stronger light absorber than silicon.”

With this in mind, how does it compare to a conventional solar cell? Brandon says its performance is dependent on three things: the amount of sunlight; the efficiency of the solar cell; and its total area.

“Under standard conditions, a nanocrystal solar cell operating at 10% efficiency can produce 100W of power per square meter. This is approximately half the output of a high-quality silicon cell,” he says.

“With further research it is expected that the performance of nanocrystal cells will continue to increase and match the performance of conventional cells. We also need to do more lifetime studies to make sure that these cells will last many years without a drop in performance.”

This project has been underway for just over three years, but with sufficient funding, it is likely that this technology could enter the market in the next five years.

“Currently I am working on better understanding the electrical properties of these solar cells. This should provide clues on how we can further improve device performance,” Brandon explains.

“I am also working on how these cells can be increased from the small scales used in lab research to the much larger sizes needed for commercial applications.”

Nevertheless, nanocrystal technology is certainly the way of the future for solar cells and electricians would do well to keep an eye out for it in the coming years.

“It is likely that the installation process will be quite different from the way solar is installed now. Once this technology enters the market in a few years’ time, it will be those who are best prepared for this change that stand to benefit the most.”