Laboratory of Photonics and Interfaces EPFL in Lausanne / Switzerland – 24.9.2019

Lecture by Prof. Michael Grätzel

Michael Grätzel is a professor at the École Polytechnique Fédérale de Lausanne. In 1991, he developed the so-called Grätzel cell, a solar cell, that works on the principle of photosynthesis and could offer a cost-effective alternative to conventional silicon-based photovoltaic systems. Prof. Grätzel sees the dye-sensitized solar cell as a supplement to silicon solar cells for application in products that work in ambient light i.g. products that can work with low power or can be permanently charged. He explains, that all colours can be produced. However, red, blue and green are best in terms of efficiency and have about the same level of performance. Also, there are cells that work in the ultraviolet and infrared range. There are already various products on the market that use the principle of the DSC, such as the hiking backpack made by the company G24 Innovation with an integrated flexible dye-sensitized solar cell. An integrated battery is constantly charged, even in low light conditions and thus can always supply power. In addition, Prof. Grätzel shows a DSC from a Korean manufacturer that was made for direct sunlight. In it, 16 cells are interconnected within one module (about 30cm x 60cm) and generate more than 10 V at full exposure. The company H.Glas has also developed a number of demo products, including a soundproof wall, windows for office buildings and facades, all of which show the potential of dye-sensitized solar cells.

Lecture and experiment by Thomas Paul Baumeler from Laboratory of Photonics and Interfaces

Thomas Paul Baumeler, assistant of Prof. Michael Grätzel, explains, that first of all, renewable energies are the way to the future due to the rising global energy consumption and global warming. Above all, the solar energy technology has not yet reached ist full potential. In theory, we could already supply the entire globe with electricity from solar energy by using an area the size of Spain. Baumele also explains the unique features of the dye-sensitized solar cell: The great advantage of DSC in contrast to silicon solar cells is the fast paced amortization time. Further advantages of the DCS are an uncomplicated and low cost production and in addition to that a production of electricity even in very low light conditions (50% of maximum power on cloudy days), which makes the sky orientation obsolete. Finally, Baumeler shows the structure and the effect of the DSC on the basis of a short video and a small experiment.

Guided tour around the labs and the EPFL Congress Center with DCS-façade by Felix Thomas Eickemeyer, scientist at the Laboratory of Photonics and Interfaces

Felix Thomas Eickemeyer is a scientist at the Laboratory of Photonics and Interfaces. He gave us a tour of the building and showed us the different laboratories. The working group around Prof. Michael Grätzel and Prof. Hackfelder in the LPI in Lausanne has 80 employees and 15 laboratories, in which there are mainly dye-sensitized solar cells and perovskite solar cells produced, researched and tested. For example, the cells are irradiated in solar simulators with a power of up to 1000 watts in order to simulate sunlight and thus be able to determine their efficiency precisely, as well as simulating and examining tests under low-light conditions. In addition, long-term stability tests can be performed, therefor the cells are artificially aged in order to determine their lifespan. At the end, Mr. Eickemeyer showed us the solar-cell façade made by Solaronix, which was installed at the EPFL congress center.

Thanks to Michael Grätzel, Thomas Paul Baumeler and Felix Thomas Eickemeyer for the insights and guided tour


text: Johanna Denecke, Leopold Seiler, Anna Maxwell, Lu Meiying