Mei Fang

An introduction of Dye sensitized solar cell Energy resources: As we know there are some ways to get energy so that electrical can be generated, like fossil fuel, solar power, nuclear power, wind power, tidal power, geothermal power etc.1 In all these resources, fossil fuel (including coal, oil and gas) has contributed a lot in the history, and even nowadays, it is the major energy resource for human being. However, this is not a renewable energy resource, and products from the burning of fossil fuel contribute to the pollution of the atmosphere. For the developments of our next generation, renewable and environment protective energy resources need to be developed. Solar power: Among all the clean energy resources, solar power is the most powerful energy resource. It was said if people can harness properly, the energy from solar to the earth in one minutes can be enough to meet human’s demands for one year! This powerful energy supply should not only be used in drying clothes, or heating water! Thanks to Becquerel, the discovery of photovoltaic effect makes it possible to create electrical from sun light.2 The first solar cell was then built by Charles Fritts in 1883 with 1% efficient.3 With the development of solar cell in last century, the efficient can be 42.4% in nowadays.3 However, the cost of the high efficiency cell make it uncompetitive with the traditional energy source. Low-cost solar cell was developed in 1990s as the third generation of solar cell: the dye sensitized solar cell. Dye Sensitized Solar Cell (DSSC): DSSC is a class of low-cost solar cell based on a semiconductor layer between a photo-sensitized anode and an electrolyte, invented by Michael Grätzel and Brian O’ Regan in 1991.4 It is technically attractive because of the low-cost raw materials and the simple manufacture process.5 A DSSC is constructed by a transparent electrode (usually ITO glass), a dye sensitized semiconductor layer (TiO2 particles surrounded by dye), an electrolyte (iodine ionic solution) and a counter electrode. The sunlight goes through the transparent electrode and captured by the dye sensitized semiconductor layer, of which the electrons in the valence band are excited into conduct band. The electrons are then transported to the counter electrode through the electrolyte and therefore photo-voltage and photo-currents are created in the cell. The reported efficiency of DSSC can reach 11%, much lower than the reported efficiency of traditional Si solar cell of 42%, but its cost is about 1/10 of a Si solar cell. Besides, a DSSC can even be used in room with low requirement of light. References: 1 Alternativeenergy, (2010), p. http://www.darvill.clara.net/altenerg/index.htm. 2 Wikipedia, (2011), p. http://en.wikipedia.org/wiki/Photovoltaic_effect. 3 Wikipedia, (2011), p. http://en.wikipedia.org/wiki/Solar_cell. 4 Wikipedia, (2011), p. http://en.wikipedia.org/wiki/Dye-sensitized_solar_cell. 5 Energyer, (2005-2009), p. http://www.energyer.com/Know_How/dye-sensitized-solar-cell.html.