An international research team led in part by Monash University says it has developed a commercially sized tandem solar cell that replaces the scarce metal indium with abundant tin oxide, a manufacturing advance that could support lower-cost production of high-efficiency solar panels.
According to Monash University, the findings, published in Science, demonstrate the first high-performance, commercially sized indium-free perovskite tandem solar cell. The researchers said the technology replaces indium-based oxide with tin oxide, a material that costs around one per cent as much, while maintaining strong performance.
Professor Yuan Cheng, from Monash Suzhou and the Department of Materials Science and Engineering at Monash University, said the achievement showed the technology could move beyond laboratory-scale 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.”
Monash University said reducing reliance on indium is becoming increasingly important as demand for solar energy grows, noting the metal is also used across a range of electronic products and its limited supply presents challenges for large-scale manufacturing.
The researchers said they replaced indium with tin oxide using a low-damage reactive plasma deposition process, producing tandem solar cells that achieved a certified efficiency of 31 per cent in a commercially sized 207.9 cm² mini-module while also improving durability. According to the team, the devices withstood heat, humidity and more than three months of outdoor operation while maintaining strong performance.
Professor Cheng said exceeding 30 per cent efficiency in a commercially sized tandem module represented a significant technical milestone.
“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,” he 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 research was led by a collaborative team including Professor Yuan Cheng of Monash University, Professors Xiaohong Zhang and Xinbo Yang of Soochow University, and Dr Zijia Li of Chint New Energy Technology Co. Ltd, together with researchers from multiple universities and photovoltaic industry partners. The findings were published in the journal Science.
