Sunday, September 5, 2010

Plasmonic solar cell

Plasmonic Solar Cells (PSC) are known as photovoltaic devices. They have great potential in driving the cost of solar power down. In order for the solar cell (SC) technology to be a viable energy source to compete with fossil fuels, the price needs to be reduced 2-5x. Approximately 90% of the market for solar cells use silicon wafers. These wafers are typically around 200-300μm and
constitute about 40% of the cost.

PSCs are a type of thin-film SC which are typically 1-2μm thick. They also use substrates which are cheaper than silicon, such as glass, plastic or steel. The biggest problem for thin film SCs is that they don’t absorb as much light as the current SCs. Methods for trapping light on the surface, or in the SC are crucial in order to make thin film SCs viable.

Current SCs have ways of trapping light. However, their method is to create pyramids on the surface which have dimensions bigger than most thin film SCs. Making the surface of the substrate rough (typically by growing SnO2 or ZnO on surface) with dimensions on the order of the incoming wavelengths and depositing the SC on top has been explored. This method increases the photocurrent, but the thin film SC would then have poor material quality.

Other methods have been explored for increasing the absorption of light in thin film SCs. One method which has been explored over the past few years is to scatter light using metal nanoparticles excited at their surface plasmon resonance.Different approaches using these metal nanoparticles and the basic principles which govern how the scattering/absorption is increased will be the focus of the following information.

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