Soup Up Solar Cells with Nanotechnology
For solar cells to generate much of the electricity needed in the future, the cost must be reduced and efficiency increased. Nanotechnology may be able to do that. Solar cells are costly to produce and install, and the energy used to create solar cells is currently more than their typical energy savings over several years.
Several intriguing examples of how nano is improving solar cells may help you understand the types of advances in the field of energy that could be possible.
International Solar Electric Technology and Nanosolar are involved in making lower-cost solar cells using semiconductor nanoparticles. By 2012, Nanosolar intends to be capable of making enough solar panels to generate more than 100 megawatts. The company says their solar cells will replace the energy used to manufacture them in a few months, rather than the years it takes to recover the energy used in making a conventional solar cell.
Konarka Technologies, Global Photonic Energy Corporation, Solarmer Energy, and others are working on developing organic solar cells, which have a more efficient interface between the negative (n) and positive (p) layers. Their products could improve the efficiency of organic solar cells from 1 percent to about 6 to 8 percent.
Although this is only about half the efficiency of conventional solar cells, organic solar cells have greater flexibility. Konarka Technologies is currently supplying solar cells using this technology to manufacturers of backpacks that charge cell phones.
Researchers at the New Jersey Institute of Technology have demonstrated that combining carbon nanotubes and buckyballs in an organic solar cell can increase the chance that electrons will escape the solar cell before being absorbed by a molecule in the organic layer.
In this process, the buckyballs and nanotubes combine in a snake-like structure. When sunlight hits the organic molecules, it generates an electron. With luck, the electron will encounter a buckyball. The electron is then absorbed by the buckyball and travels down the carbon nanotube to the electrode on the outside of the solar cell and then to the wires connecting the solar cell to the device to be powered.
The nano brain trust at Stanford University has also found a way to trap light in organic solar cells for a longer period of time. By using a nanoscale organic layer, which is much thinner than the wavelength of light, the light stays in the solar cell longer and excites more electrons, producing more electricity.