A team of Japanese scientists used manganese and inorganic components to boost the stability and efficiency of perovskite solar cells. The Energy Materials and Surface Sciences Unit at the Okinawa Institute of Science and Technology Graduate University (OIST) developed devices using a new perovskite material that they say makes the process relatively cheaper to produce.
The researchers used inorganic instead of organic components, which helps provide stability to the cells in face of heat from the sun. They also doped the new cells with manganese to improve their performance. It changes the crystal structure of the new material, boosting its light harvesting capacity, said the research team.
Their work was recently published in Advanced Energy Materials. The reference CsPbIBr2 cell reaches a power conversion efficiency (PCE) of 6.14%, comparable with the previous reports.
According to the authors, the new material has several key features: 'First, it is completely inorganic – an important shift, because organic components are usually not thermostable and degrade under heat. Since solar cells can get very hot in the sun, heat stability is crucial. By replacing the organic parts with inorganic materials, the researchers said that they made made the perovskite solar cells much more stable. "The solar cells are almost unchanged after exposure to light for 300 hours," says Zonghao Liu, an author of the paper.
"Just like when you add salt to a dish to change its flavor, when we add manganese, it changes the properties of the solar cell," explained Liu.
They also replaced gold with carbon for electrodes to transport current between solar cells and external wires. Carbon electrodes are cheaper and easier to produce, as these can then be printed directly on the cells, compared to gold.
The all-inorganic perovskite solar cells are built in several layers. The bottom layer is glass, which is several millimeters thick; the second layer is a transparent conductive material called FTO. Then comes an electron sensitive layer made from titanium oxide. The fourth layer is the photoactive perovskite, the top layer is carbon (see photos below).
Prof Yabing Qi led the team that also had Dr Jia Liang and Dr Zonghao Liu working on the research. It is an ongoing research project to improve the efficiency and durability of perovskite cells and includes developing a process of fabricating the cells on a commercial scale.
.png?w=50&fm=png){kind=logo}