Aussie-led solar breakthrough slashes costs
An international team of researchers, including experts from Monash University, has developed a world-first, commercially sized tandem solar cell that eliminates the need for a scarce and expensive metal.
The breakthrough, published in the prestigious journal Science, replaces costly indium-based oxide with abundant tin oxide. The new material costs just one per cent of the price of indium, achieving this dramatic cost reduction without sacrificing the solar cell’s performance.
This advance brings next-generation tandem solar cells a major step closer to commercial production, offering the potential for cheaper solar panels that can generate significantly more electricity from the same amount of sunlight.
Professor Yuan Cheng, from Monash Suzhou and the Department of Materials Science and Engineering at Monash University, said the milestone marks the first realisation of a large-area, highly efficient indium-free perovskite tandem solar cell. The success demonstrates that the technology can be scaled effectively beyond small, laboratory-sized devices.
“Considering the cost of tin is a mere one per cent of that of indium, this breakthrough unveils a new material paradigm and a highly viable engineering route for low-cost, sustainable, and scalable tandem photovoltaics,” Professor Cheng said.
“Ultimately, this work is of paramount strategic importance for propelling the industrialisation and terawatt-scale deployment of next-generation ultra-high-efficiency photovoltaic technologies.”
As global demand for solar energy continues to grow, reducing the industry’s reliance on scarce materials has become increasingly critical. Indium is currently used across a wide range of modern electronics, and its limited global supply presents significant challenges for large-scale manufacturing.
By replacing indium with tin oxide using a low-damage reactive plasma deposition process, the researchers created solar cells that achieved a certified efficiency of 31 per cent in a commercially sized mini-module. The new design also significantly improved the device’s overall durability.
During rigorous testing, the new solar devices successfully withstood heat, humidity, and more than three months of continuous outdoor operation while maintaining strong performance levels.
Professor Cheng said achieving more than 30 per cent efficiency in a commercially sized tandem module is a major technical milestone, proving that high performance can be maintained without relying on scarce, high-cost materials.
“The research team developed a reactive plasma deposition (RPD) process for tin oxide (SnOx) films to serve as the recombination layer, achieving a remarkable certified efficiency of 33.6 per cent on 1 cm2,” Professor Cheng said.
“By further extending the application of RPD-SnOx to both the front and rear transparent electrodes, we successfully fabricated indium-free tandem solar cells. Remarkably, we scaled this technology up to a 207.9 cm2 mini-module, obtaining an outstanding certified efficiency of 31.0 per cent.”
The breakthrough was achieved by a collaborative international team led by Professor Yuan Cheng of Monash University, alongside Professor Xiaohong Zhang and Professor Xinbo Yang from Soochow University, and Dr Zijia Li from Chint New Energy Technology Co. Ltd. The project also involved multiple renowned universities and leading enterprises across the photovoltaic industry.