Jan 9 2008
People who follow nanotechnology news have become accustomed to hearing how scientists are making super-small devices even smaller. But here’s a headline from Prof. Arie Zaban, Head of Bar-Ilan University’s Nanotechnology Institute: using nano-based methods, he’s managed to create a solar cell that’s 100 times bigger than his previous design.
Prof. Zaban is a leading expert in photovoltaics, a technology that uses the sun’s rays to produce electricity. In a recently patented technique, Prof. Zaban demonstrated how metallic wires mounted on conductive glass can form the basis of solar cells that produce electricity with efficiency similar to that of conventional, silicon-based cells, but are much cheaper to produce. Now, this line of research has taken a “giant” step forward: while Prof. Zaban’s earlier efforts produced photovoltaic cells just one square centimeter in size, he has now achieved a cell measuring ten by ten – something that Prof. Zaban says will significantly boost its usefulness in technologies that seek to produce commercial amounts of solar power.
“Initially, we created linked arrays of very small cells, which led to a loss of efficiency because the sunlight hitting the space between the cells was not converted to electricity,” Prof. Zaban explains. “Our new design offers ten times more surface area, which means that more of the array is actively capturing the sun’s energy. This makes our new cell a practical choice for solar energy production.”
Practical solar energy, says Prof. Zaban, depends on both efficiency and cost. Another of his recent discoveries brings costs down by economizing on platinum – an expensive metal embedded on the glass cell’s surface. “We’ve found a way to produce platinum nanodots – tiny crystals measuring only a few nanometers in diameter,” Prof. Zaban explains, adding that this highly reactive metal is an important part of his solar cell’s operation. “Thanks to this technique – now under consideration for a patent – we reduce the amount of platinum needed by a factor of 40.”
In his previous research, Prof. Zaban pioneered a low-cost solar technology in which nano-sized particles of an inexpensive semiconductor material are arranged in a sponge-like array on top of flexible plastic sheets. Key to his system is the use of an organic dye that allows the semiconductor – transparent in its natural form – to absorb light.
“Cost is an important factor in the success of any solar technology,” Prof. Zaban says. “To become widely adopted, solar cells must generate electricity at lower cost than what we now spend on fossil fuels. At the same time, we have to make the basic infrastructure extremely affordable – because the third-world countries that stand to reap the most benefit from solar power usually lack the money to invest in it. By making cells more efficient and keeping material costs down, nano-based techniques are moving us closer to that goal.”
Currently, Prof. Zaban serves as an advisor to Orionsolar, a Jerusalem-based company that has entered into partnership with Bar-Ilan and is developing commercial applications for inexpensive, dye-based photovoltaics based on his work. And according to Prof. Zaban, lowering costs are leading to rising expectations in the alternative energy community.
“Given the state of the technology, I believe that the new solar cells will be available commercially within the next five years,” he says. “This will mark the beginning of a whole new path that combines independence from fossil fuels with a greener, more sustainable future.”