Natural Dye-Sensitized Solar Cells Based on Highly Ordered TiO2 Nanotube Arrays

The dye-sensitized solar cells (DSSCs) have been fabricated using highly ordered TiO2 nanotube arrays as photoelectrode and natural dyes as photosensitizers. The natural dyes were extracted from the abundant plants in the tropical region, such as Tradescantia zebrina, kapok, and pitaya. The dyes could chemically couple with TiO2 nanotubes and effectively convert visible light into electricity in DSSCs. A power conversion efficiency could be achieved up to 0.3% in the solar cell sensitized by the extracts from kapok with a short-circuit current of 0.86 mA/cm2. Furthermore, the influences of the crystal structure of TiO2 nanotube arrays on the performance of the natural DSSCs were discussed.