Researchers from Japan have developed a "fiber-type TCO-less dye-sensitized solar cell." This solar cell is composed of dye-sensitized solar cell layers wrapped around a glass fiber measuring 3.5 cm in length and 9 mm in diameter.  
The research team was led by Professor Shuji Hayase from the Institute of Life Science and Systems Engineering at Kyushu Institute of Technology (KIT). The researchers used a layer of titanium oxide, a layer of sensitizing pigment, and a layer of porous titanium (porous Ti) as the electrode (anode). They also employed a porous layer containing electrolytes such as iodine, along with a layer of platinum (Pt) and titanium as the other electrode (cathode). These two electrodes were sequentially wrapped around the glass fiber. Except for the two ends of the glass fiber, the entire solar cell was covered with titanium.  
When light is introduced from one end of the glass fiber, it is absorbed by the dye in the solar cell and converted into electricity. If the fiber is slightly tilted, total internal reflection does not occur in the glass beneath the surface before the light exits from the other end. Currently, the conversion efficiency demonstrated by this solar cell is just over 1% when using a specific dye. This figure is somewhat low, and since the glass fiber used in the cell has a diameter of 9 mm but a length of only about 1.5 cm, approximately 90% of the light entering from one end and exiting from the other is not converted.  
In the future, the net conversion efficiency of this solar cell is expected to reach 10%. The issue of wasted light can be addressed by increasing the length of the optical fiber or reducing its diameter. One of the key differences between this new solar cell and standard dye-sensitized cells is that the new cell does not use a transparent electrode (transparent conductive oxide film, TCO). The researchers plan to utilize near-infrared energy, which is not currently used by existing dye-sensitized solar cells, to generate electricity.