A team of researchers from Huazhong University of Science and Technology in China has developed an all-perovskite tandem solar cell with a record-breaking power conversion efficiency of 28.49%. This achievement, detailed in the paper Surface chemical polishing and passivation minimise non-radiative recombination for all-perovskite tandem solar cells, was published in ‘Nature Communications’. The tandem solar cells utilise two perovskite materials to capture a broader spectrum of sunlight, enhancing efficiency. Beyond high performance, the cells also demonstrated durability, maintaining optimal functionality after 550 hours of continuous operation. Perovskite is gaining attention as a potential replacement for silicon in solar cells, being more cost-effective and flexible for various configurations, including bendable applications. While commercial use remains limited, the researchers were able to minimise defects in the material, contributing to the efficiency milestone. The team successfully developed a Sn–Pb mixed perovskite film, which significantly boosted the cell’s performance. The report noted that Sn–Pb mixed perovskite solar cells with bandgaps of 1.32 and 1.25?eV achieved power conversion efficiencies of 22.65% and 23.32%, respectively, with the two-junction tandem cell reaching the certified efficiency of 28.49%. A key challenge in improving the efficiency of these cells has been overcoming surface defects that lead to non-radiative recombination loss in Sn–Pb mixed narrow bandgap perovskite films. To address this, the researchers employed a surface reconstruction strategy using a polishing agent, 1,4-butane diamine, and a passivator, ethylenediammonium diiodide, to eliminate Sn-related defects and passivate vacancy defects. Earlier this year, researchers from the National University of Singapore achieved a 27.1% efficiency with a novel triple-junction solar cell, while efforts by MIT and other institutions are exploring ways to improve perovskite solar panels through nanoscale engineering. (Mercom)