Kaleigh Harrison
A research team at the University of Sydney has developed the world’s largest and most efficient triple-junction perovskite-perovskite-silicon tandem
solar cell, a step that could bring next-gen solar closer to large-scale deployment. Spearheaded by Professor Anita Ho-Baillie from the University's
Nano Institute, the study demonstrates not only high performance at scale but also strong durability under real-world testing conditions.
The larger 16 cm² device achieved a power conversion efficiency of 23.3%, verified independently through steady-state testing—a new benchmark for large-area tandem cells. A smaller, lab-scale 1 cm² version reached 27.06% efficiency and passed rigorous thermal testing, including the International Electrotechnical Commission’s (IEC) Thermal Cycling test, which puts solar cells through 200 cycles of extreme temperatures between -40°C and 85°C. After 400 hours under continuous illumination, the smaller device retained 95% of its initial efficiency.
These results, published in Nature Nanotechnology, address two of the most persistent challenges facing perovskite solar tech: scalability and stability.
Perovskite materials have long promised high-efficiency, low-cost production, but durability and real-world performance have often fallen short of expectations. This work suggests that may be changing.
Advanced Materials Engineering Drives Performance Gains
Key to the project’s success was the team’s reengineering of perovskite composition and interlayer materials. Methylammonium, a commonly used but unstable compound in perovskite cells, was replaced with rubidium to strengthen the crystal lattice and reduce degradation over time. To improve surface stability, the researchers also swapped lithium fluoride for piperazinium dichloride.
A major technical development came in the form of rethinking the interconnection layer between the two perovskite junctions. Using high-resolution transmission electron microscopy, the team observed that gold formed discrete nanoparticles rather than a continuous layer. This insight allowed them to fine-tune nanoparticle coverage, optimizing both light absorption and charge transport through the cell.
The tandem structure's design allows each layer to capture different parts of the solar spectrum, increasing total energy conversion efficiency beyond what traditional silicon cells can offer. With single-junction silicon cells approaching their theoretical limits, multi-junction alternatives like this present a viable path to continued performance improvements.
