We develop new energy materials in order to reduce costs and increase the efficiency. Photo: F.Steinmann

Solar cells electrical power from Sunlight

Solar cells convert sunlight to electrical energy. The solar power generated in Germany on sunny days meets almost half of the total power demand in the country. Solar panels made of crystalline silicon cells are widely available in the market. They offer high levels of efficiency, but the manufacturing costs cannot be easily reduced any further. To expand the use of solar energy further, new technologies are therefore needed. For this reason, researchers at the HZB are developing combinations of materials that offer the prospect of being less expensive.

SEM image that shows different layers of a perovskit silicon tandem solar cell.

Thin-film solar cells

We are concentrating on thin-film solar cells made of various systems of materials. The extremely thin layers require less material and energy for their fabrication. We are conducting advanced development on silicon thin-film cells, while investigating cells made of combinations of materials such as copper, indium, gallium, sulphur, and selenium (CIGS cells), those of copper, zinc, tin, and sulphur (kesterite), and solar cells made of perovskites, a new organic material. The combination of various materials is especially promising. Tandem
solar cells of silicon and perovskites can utilise a wider portion of the solar spectrum than silicon solar cells alone, for example.

Vacuum chamber: Scientists investigate thin film samples with the soft X-ray radiation from BESSY II. Photo: T. Friedrich

Improve solar cells

However, thin-film solar cells have not yet achieved the efficiency levels that are theoretically possible. The cause: many electrons are lost through various layers of material or at boundary layers. Using the soft X-rays of BESSY II, researchers can analyse exactly why these losses occur. This helps to further improve the solar cells.