Winchester, UK - A Japanese research group, which is led by Shuji Hayase, professor at the Graduate School of Life Science and Systems Engineering of the Kyushu Institute of Technology (KIT), has developed a 'fiber-type TCO-less dye sensitized solar cell'.
The prototype was unveiled it at the 56th Spring Meeting, 2009 of the Japan Society of Applied Physics, which took place from March 30 to April 2, 2009, at the University of Tsukuba.
The solar cell is composed of dye sensitized solar cell layers concentrically formed around a glass rod with a length of 3.5 cm and a diameter of 9 mm. A layer of titanium oxide and a sensitizing pigment, a porous titanium (Ti) layer serving as an electrode (anode), a porous layer containing an iodine solution and other electrolytes, and a layer of platinum (Pt) and Ti serving as another electrode (cathode) are formed in order around the rod. The solar cell is covered with Ti except for both ends of the glass rod.
Light entering from one end of the glass rod is absorbed by the pigment in the solar cell and converted into electricity if it is at an angle that does not result in total reflection on the glass inner surface before exiting the other end of the rod.
The solar cell currently exhibits a conversion efficiency of slightly higher than one percent when using one type of pigment. Although the efficiency value seems low, the device made has a large diameter of 9 mm, and the length of the portion serving as a solar cell is only about 1.5 cm. As a result, about 90 percent of light incident from one end goes out from the other end without being converted.
The net conversion efficiency of the solar cell itself is likely to reach about 10 percent. The wasted light problem can be overcome by increasing the fiber length or by reducing the fiber diameter.
A key difference between the new solar cell and standard dye sensitized solar cells is that the new cell does not use a transparent electrode (TCO). KIT plans to utilize near-infrared energy, which has not been used for existing dye sensitized solar cells, to generate electricity.
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