A new study led by The Australian National University (ANU) could be the next step toward highly efficient and affordable solar technology.
Study co-author Dr Heping Shen from the ANU School of Engineering said the current solar cell market is dominated by silicon-based technology – which is nearing its efficiency limit.
“In order to continue the transition to a renewable energy-based economy, we need to keep reducing the cost of solar energy, and the best way to do that is to increase the efficiency of solar cells,” Dr Shen explained.
“If we can have a cheap source of energy that is also clean – who wouldn’t want to use it?,” she added.
In collaboration with researchers from the California Institute of Technology, the ANU engineers have developed a way to combine silicone with perovskite (a calcium titanium oxide mineral), to more efficiently convert sunlight into electricity.
The key is the way the materials are joined together to form a ‘tandem solar cell’ (essentially one solar cell on top of another) and this model may be the simplest ever developed.
“We have constructed a tandem structure that is unconventional. When engineers combine two cells they usually need to have an interlayer to allow electrical charge to be transferred easily between the two cells, so they can work together,” Dr Shen shares.
Co-author Dr Daniel Jacobs explains that it’s like making a club sandwich with extra bread in the middle – it plays a structural role, but the sandwich would taste better without it.
“We’ve found a new way to simply stack the two cells together, so they’ll work efficiently with each other – we don’t need the interlayer, or extra bread, anymore,” he said.
This minimises energy waste and simplifies the structure, with the intention of making solar cheaper and easier to produce.
Dr Jacobs further states that with tandems it’s crucial to demonstrate a fabrication process that is as simple as possible, otherwise the additional complexity is not worthwhile from a cost perspective.
“Our structure involves one less fabrication step and has benefits for performance too,” he says.
Lastly, Dr Jacobs mentions that while it can be difficult to combine two materials in a tandem arrangement, once you get it right the efficiency goes up very quickly, well beyond what is possible with silicone by itself.
“We’ve already reached 24 per cent improvement in efficiency with this new structure, and there’s plenty of room left to grow that figure,” Dr Jacobs comments.
The study was funded by an Australian Renewable Energy Agency grant, as part of a project in collaboration with UNSW and Monash University.
A published online research paper on the study can be found here.