A team at MIT has discovered a way to enhance the power-conversion efficiency of solar cells by using nano-viruses to carry out assembly at the microscopic level.
When sunlight reaches a material that harvests light, electrons are emitted that could be harnessed to create an electric current. The research paper has appeared online in the journal Nature Nanotechnology, and says that carbon nanotubes can improve the capability of electrons gathered from a solar cell’s surface.
Graduate students Xiangnan Dang and Hyunjung Yi in collaboration with Angela Belcher, the W. M. Keck Professor of Energy, and other researchers discovered that a genetically designed virus called M13 infecting bacteria can control the nanotubes’ structure on a surface, separating them to prevent short circuits and clumps.
The researchers used a solar cell type called dye-sensitized solar cells, a light and cheap variety, in which the active layer consists of titanium dioxide. The virus-built structures improved the power conversion ability. This enhanced occurs even when the viruses and nanotubes weigh 0.1% of the cell.
In a solar cell, the light energy dislodges electrons from the solar-cell. The electrons should be channeled toward a receptor from where a current flows to fuel a battery or device. Then they return to their earlier material, and the whole cycle restarts. The system is designed to improve the second step, to enable the electrons to find their way.
The viruses contain peptides that bind tightly to carbon nanotubes separating and holding them down in place. A single virus can contain 5 to 10 nanotubes. The virus can also generate a coating of titanium dioxide (TiO2) over each nanotube, keeping the titanium dioxide close to the nanotubes holding the electrons. The viruses dissolve the nanotubes in water, enabling them to integrate the nanotubes into the solar cell through a water-based technique at room temperature.
The research program was supported by a grant from Eni, an Italian company, through the MIT Energy Initiative’s Solar Futures Program.
Source: http://www.mit.edu