Researchers in Singapore have developed ultrathin perovskite solar cells with absorber layers as thin as 10 nm, achieving high transparency and stable efficiencies up to 12%. These cells offer scalable, design-flexible photovoltaics suitable for seamless integration into buildings, balancing optical transparency with electrical performance without sacrificing scalability or manufacturability. The study showed that the cells achieved power conversion efficiencies of 7%, 11%, and 12% with absorbers of 10 nm, 30 nm, and 60 nm respectively, maintaining their performance even in low-illumination conditions. Perovskite materials in buildings can generate electricity without changing their appearance, aiding in the growth of distributed renewables, with tunable optical properties and the ability to be manufactured on a large scale, potentially leading to further improvements in light-utilization efficiency in the built environment.