Researchers at the University of Queensland (UQ) are harnessing the properties of quantum dots (QDs) to make solar cells that capture a wider range of light for energy, are more stable in their energy production, and can be applied to curved surfaces. According to the team led by professor Lianzhou Wang, UQ has achieved a new world record for QD solar cell efficiency — going from 13.5% to 16.6%, a nearly 25% gain in efficiency. The researchers developed a surface engineering strategy to overcome roughness and instability on the surface of QDs, which can interfere with efficiency. An oleic acid ligand-assisted cation-exchange strategy allowed controllable synthesis of a mixed cesium and formamidinium lead triiodide perovskite system in the form of QDs. The oleic acid-rich environment facilitates the cross-exchange of cations, enabling rapid formation of perovskite QDs with reduced defect density. In addition to achieving a certified record power conversion efficiency of 16.6%, the new QD devices exhibit enhanced photostability compared with their thin-film counterparts because of suppressed phase segregation. From left: Professor Lianzhou Wang and researchers Shanshan Ding, Mengmeng Hao, and Yang Bai. Courtesy of the University of Queensland. The quantum dots developed by Wang’s team are flexible and can be printed on flexible skins to cover a range of surfaces, in contrast to the rigid, expensive materials used in conventional solar technologies. “This new generation of quantum dots is compatible with more affordable and large-scale printable technologies,” Wang said. “This opens up a huge range of potential applications, including the possibility to use it as a transparent skin to power cars, planes, homes, and wearable technology.” Wang believes that the near 25% improvement in efficiency over the previous world record could be a milestone. “It is effectively the difference between quantum dot solar cell technology being an exciting prospect and being commercially viable,” he said. The research was published in Nature Energy (www.doi.org/10.1038/s41560-019-0535-7). New research shows quantum dot solar technology that can be printed on flexible skins to cover a range of surfaces. The researchers have set what to their knowledge is a world record for the conversion of solar energy to electricity via the use of quantum dots. Courtesy of the University of Queensland.