New solar cells boost efficiency to record high
An international research team co-led by City University of Hong Kong is accelerating the commercialisation of perovskite photovoltaic technology with a new approach that boosts the efficiency of perovskite solar cells to a record high of 25%.
Traditional solar cells are made from silicon, which has good efficiency and stability, but is relatively expensive to make and can only be manufactured in stiff panels.
Perovskite solar cells offer an intriguing alternative; they can be printed from inks, making them low cost, high efficiency, thin, lightweight and flexible. However, they have trailed behind silicon solar cells in efficiency and, importantly, stability, breaking down under normal environmental conditions.
New metal-containing materials called ferrocenes could help with these problems. In this collaborative research, published in Science, researchers from City University of Hong Kong added ferrocenes made by Imperial College London into perovskite solar cells, vastly improving their efficiency and stability.
Ferrocenes are compounds with iron at their centre, surrounded by sandwiching rings of carbon. Their structure gives them excellent electron richness, which in this case allows electrons to move more easily from the perovskite layer to subsequent layers, improving the efficiency of converting solar energy to electricity.
The collaborators tried attaching different chemical groups to the carbon rings of ferrocene and discovered a combination that significantly improves the attachment of the perovskite layers to the rest of the device. This improved the stability of the device which maintained more than 98% of its initial efficiency after continuously operating at maximum power for 1,500 hours. The efficiency and stability gained through the addition of a ferrocene layer brings these perovskite devices close to current international standards for traditional silicon cells.