Joe Shapter is developing a new kind of solar cell.
Nanotube coatings on windows could deliver green energy to homes and offices in a few years.
Silicon, which is used extensively in solar cells, can conduct electricity and, after some processing, can convert light energy directly into electrical energy. However, this processing is very energy intensive and it currently takes solar photovoltaics about ten years of service to produce the energy required to make the device.
So Prof. Joe Shapter and his team at Flinders University, South Australia, looked to nature. They have designed a system based on a molecule that acts like the chlorophyll in plants.
They have attached a porphyrin compound, incorporating the metal ruthenium, to carbon nanotubes on a silicon wafer base, making an array of microscopic antennas just hundreds of nanometres high. Each antenna holds porphyrin molecules up to the sun and channels electrons from the porphyrin into the silicon substrate.
The ruthenium porphyrin is like molecules in the green pigment chlorophyll, used by plants to convert light, carbon dioxide and water to food through photosynthesis. It is much more efficient in its energy conversion (at 80 per cent) than even the best laboratory prototype solar cells (40 per cent). The silicon need not be of high purity, so it is less energy-intensive to produce than conventional solar cells.
A prototype, used as a coating on the sheet glass of a window, should be available within two years.
Contributed by the National Enabling Technologies Program of the Department of Innovation.
For more information: Flinders University, Joe Shapter, Tel: +61 (8) 8201 2005, Joe.Shapter@flinders.edu.au
