Nanoparticle with carbon nanotubes based solar cells - more efficient and practical.
Experts have demonstrated a way to significantly improve the efficiency of solar cells made using low-cost, readily available materials, including a chemical commonly used in paints. The researchers added single-walled carbon nanotubes to a film made of titanium-dioxide nanoparticles. This process doubles the efficiency of cell for converting ultraviolet light into electrons when compared with the performance of the nanoparticles alone. Titanium oxide is a main ingredient in white paint.
Such cells are appealing because nanoparticles have a great potential for absorbing light and generating electrons. But so far, the efficiency of actual devices made of such nanoparticles has been considerably lower than that of conventional silicon solar cells. That's largely because it has proved difficult to harness the electrons that are generated to create a current. In fact, when electrons generated by absorbing light by titanium –oxide, absence of carbon nanotubes with the titanium-oxide particles make the electrons jump from particle to particle before reaching an electrode. On the path many electrons do not able to reach the electrode, thus fail to generate an electrical current. The carbon nanotubes "collect" the electrons and provide a more direct route to the electrode, improving the efficiency of the solar cells.
The new carbon-nanotube with titanium –oxide nanoparticle system is not yet a practical solar cell, as titanium oxide only absorbs ultraviolet light; most of the visible spectrum of light is reflected rather than absorbed. Researchers have also demonstrated ways to modify the nanoparticles to absorb the visible spectrum.
Several other groups of researchers are exploring approaches to improve the collection of electrons within a cell, including forming titanium-oxide nanotubes or complex branching structures made of various semiconductors. Using carbon nanotubes as a conduit for electrons from titanium oxide is a novel idea, and once it is successful the cheaper variety of efficient solar cells can be developed.
More research is needed towards development of efficient solar cells, as solar energy is renewable, clean and unlike grain based bio-fuel, solar energy is not agriculture based thus do not utilize farm land and do not hamper food production.