New perovskite battery generates electricity for more than a thousand hours

The National Institute for Materials Science in Japan has developed a durable perovskite solar cell with an area of ​​only 1 square centimeter that can continuously generate electricity for more than 1,000 hours under sunlight with a photoelectric conversion efficiency (i.e., power generation efficiency) of more than 20%. Since this solar cell can be manufactured on the surface of plastic materials at a temperature of about 100°C, this technology will be used to develop lightweight and multifunctional solar cells.

Perovskite solar cells are considered to be the next generation of solar cells with broad application prospects because they are easier and cheaper to produce than traditional solar cells. However, perovskite solar cells also have disadvantages: they are easily degraded when they react with water molecules. It turns out that they are difficult to achieve both durability and high efficiency.

Most perovskite solar cells have a similar electricity generation mechanism. When the perovskite layer absorbs sunlight, electrons and holes are generated. These electrons and holes then migrate to the adjacent electron transport layer and hole transport layer, respectively, where they flow to generate an electric current. To improve both the efficiency and durability of perovskite solar cells, these layers and the interfaces between them need to enable electrons and holes to pass more freely, while making the interfaces impermeable to water molecules.

The research team added a hydrazine derivative containing hydrophobic fluorine atoms (5F-phz) to the interface between the electron transport layer and the perovskite layer. This interface successfully prevented water molecules that penetrated the electron transport layer from contacting the perovskite layer, thereby improving the durability of the solar cell. The use of this interface also reduced the number of crystal defects formed on the surface of the perovskite layer, which is a cause of decreased power generation efficiency. In addition, the team added a phosphonic acid derivative (MeO-2PACz) to the interface between the hole transport layer and the perovskite layer, minimizing the formation of defects in the hole transport layer, thereby improving the power generation efficiency of the solar cell.

This research was recently published in Advanced Energy Materials. In the future, the team also plans to create a database of molecules that can be integrated into interfaces, conduct data-driven research, design molecules that can improve interface properties, and develop more efficient and durable perovskite solar cells.