A statement from the ANU said the materials are joined together to form what is known as a tandem solar cell - essentially one solar on top of another, a configuration that the ANU researchers say is the simplest yet developed.
The co-author of the study in question, Dr Heping Shen from the ANU School of Engineering, said the solar market was dominated by silicon-based technology which was 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 said.
Dr Shen said the team had constructed a tandem structure that was 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," she added.
Dr Daniel Jacobs, co-author of the study, said the presence of an interlayer was like making a club sandwich with extra bread in the middle – it played 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.
The new design made the structure simpler and minimised energy waste, which would make it cheaper and easier to produce.
“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,” Dr Jacobs said.
“Our structure involves one less fabrication step, and has benefits for performance too.”
He said that while it was difficult to combine two materials in a tandem arrangement, the efficiency would increase fast once one got the process right, much beyond what was possible with silicon alone.
“We’ve already reached 24% improvement in efficiency with this new structure, and there’s plenty of room left to grow that figure,” Dr Jacobs added.
The study was funded by an Australian Renewable Energy Agency grant in collaboration with UNSW and Monash University.