The Energy of Knowledge: Michael Graetzel discussing a profitable alternative to silicon-based solar cells
There is a profitable alternative to silicon-based solar cells, the Global Energy Prize laureate-2017 Michael Graetzel is convinced. He highlighted his own development, the Graetzel cells, on March 27, within the Energy of Knowledge program. The scientist gave a lecture at KIT (Germany) on “Light and Energy – Mesoscopic Photosystems for the Generation of Electricity and Fuels from Sunlight”.
Director of Laboratory of Photonics and Interfaces at École Polytechnique Fédérale in Lausanne Michael Graetzel is one of developers of the so-called Graetzel cell operating on the principles of photosynthesis – the process similar to biochemical one and used by plants for light energy conversion into carbohydrates. The invention developed by the scientist since the 1970ies represents a profitable alternative to expensive and sophisticated technologies of photovoltaic arrays produced on the basis of silicon (in particular, the latter require expensive silicon of high purity). Compared to silicon-based batteries the Graetzel cells are rather simple and manufactured of low cost materials.
Alternative to Expensive Technologies
First Graetzel cells discovered in 1991 were based upon porous layer of nanoparticles of titanium oxide covered with organic dye. Electrons from organic dye, able to efficiently adsorb solar radiation, migrate into conductive electrode made of titan dioxide and generate the electric flux. Commercial manufacturing of such cells was started just in 2009. At the initial stage, they possessed poor efficiency performances of 3-8% and poor stability due to available unstable liquid electrolyte and organic dye inside the cells. By 2012, the efficiency of cells has been increased by 11.9%. The cell’s structure was changed: an organic pigment in the cells was transferred to hybrid organic-inorganic perovskite materials, and in 2012, solid organic semiconductor replaced liquid electrolyte. At that, a new class of devices, the so-called "perovskite solar cells" has emerged. At present, these devices are considered the most intensively studied materials in the world, and their efficiency currently exceeds 22%.
Michael Graetzel is an ultimate leader in the field of materials for solar power industry and continues his works on development of photovoltaics all over the world.
Several companies have already launched mass production of photocells based upon renewed Graetzel cells. Prof. Graetzel is the author of more than 1300 publications and two monographs, he holds more than 50 patents. He is one of the three globally most cited chemistry academicians.
The lecture was transmitted live to numerous universities via youtube livestream and can be found here