A research collaboration between the University of Sydney, Australia, and Xiamen University, China, has achieved a certified 27.06% power conversion efficiency in a 1 cm² perovskite–perovskite–silicon triple-junction solar cell, verified by an independent laboratory. Published in Nature Nanotechnology, the study introduced nanoscale interface engineering that replaced lithium fluoride with piperazine-1,4-diium chloride (PDCl) and incorporated rubidium to enhance charge extraction and device stability. The optimized design produced an open-circuit voltage of 3.16 V and maintained 95% of its performance after 407 hours of illumination. A larger 16 cm² device achieved a certified steady-state efficiency of 23.3%, one of the highest reported for scaled modules. The inclusion of ultrathin gold nanoparticles improved electrical contact and minimized optical losses, while rubidium doping reduced phase segregation. Researchers stated that these advances bring perovskite–silicon tandems closer to the 30% efficiency threshold with enhanced long-term durability and scalability.