Solar power: new generation cells are a ground-breaking development In 2010 Professor Michael Graetzel won the Millenium Technology Prize for developing a low cost solar power cell using cheap materials such as dye from berries. The Parliamentary Information Office of the Parliamentary Yearbook reports on the development of new technology by Professor Graetzel that has increased the efficiency of these solar power cells by 15%. Award winning inventor of the low-cost solar cell, Professor Micheal Graetzel, believes that an energy crisis can be avoided by harnessing the power of the sun. To this end, he is famous for inventing translucent solar cells that use titanium dioxide and organic dyes (from berries) to convert sunlight into electricity. The use of dyes in the production of these cells is reflected in their name: dye-sensitised solar cells (DSSCs). These cells provide a cheaper and more environmentally friendly source of energy than traditional silicon solar cells. Professor Graetzel has recently announced a new technological development in the production of DSSCs which has increased their power conversion efficiency by 15%. DSSCs work differently from traditional solar cells. Silicon cells absorb sunlight and generate electric charges but the silicon has to transport the charges and separate positively charged carriers from negatively charged carriers. To achieve this requires solar grade silicon which is 99.9999% pure. DSSCs differ from this. They create energy from sunlight mimicking a natural process found in nature - called photosynthesis - that green leaves use to generate energy from the sun. Organic dye molecules generate the charges. DSSCs have very distinct properties. They have the tremendous advantage of working in low light, which means that they work well in cloudy weather, and can absorb diffused sunlight. They are produced at low temperatures, transparent and can be painted on to flexible surfaces. In addition to this, they are relatively inexpensive and environmentally friendly to produce; their production does not involve any energy-intensive high-vacuum methods or produce toxic waste. Professor Graetzel, Director of the Laboratory of Phototonics and Interfaces at the Ecole Polytechnique Federale de Lausanne in Switzerland, has recently described a further breakthrough in DSSC technology. At the heart of this development is a new two-step process for DSSC production which establishes a world record efficiency. Unlike most DSSCs the new cell comes in a solid state and involves a 2-stage process to produce a perovskite layer; the dye material layer used for energy-harvesting. In the first stage of the process one component of perovskite is deposited directly onto a metal oxide film base. This is exposed to a solution containing another component of perovskite. When the two components come together they immediately react and convert into the complete light sensitive material. The new methodology has resulted in an unprecedented 15% efficiency in light to electricity conversion for the DSSC, exceeding that of conventional silicon based solar cells. This technological achievement is important because it could significantly lower the price per watt of power produced by solar cells. Commenting on the work, Dr James Ball, a researcher at the Department of Physics, University of Oxford, said: “The achievement of 15% efficiency is an important landmark and this technology provides the most efficient solution-processed solar cells by a long way. This development makes them competitive in efficiency with silicon solar cells, but at a much lower cost.” parliamentaryyearbook.co.uk Email: [email protected]
Posted on: Thu, 08 Aug 2013 10:15:19 +0000
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