University of Wisconsin-Madison researchers have developed a cost- and energy-efficient photovoltaic cell that uses carbon nanotubes as the photoconducting material. Unlike semiconductor materials, carbon nanotubes absorb different spectra of light depending on the diameter and chirality of each tube. A variety of nanotube sizes and chiralities can be used within a photovoltaic array to significantly increase the efficiency over current technologies.
The carbon nanotube Schottky barrier photovoltaic cell earned the Wisconsin Alumni Research Foundation (Madison, WI) United States Patent 7,645,933 (January 12, 2010).
Inventors UW-Madison Materials Science and Engineering Professor Max Lagally, Professor Mark Eriksson, Todd Narkis, and Matt Marcus developed the patented carbon nanotube Schottky barrier photovoltaic cells and methods and apparatus for making the cells. The photovoltaic cells include contacts made from a first contact material which contact through photoconducting carbon nanotubes bridges to a second contact material.
A Schottky barrier is formed at the interface between the first contact material and the carbon nanotubes while at the interface between the second contact material and the carbon nanotubes, a Schottky barrier for the opposite carrier is formed, or a small, or no Schottky barrier is formed. It is the Schottky barrier asymmetry that allows the photo-excited electron-hole pairs to escape from the carbon nanotube device.
The invention also includes a novel method of manufacturing the nanotube array. Normally, nanotubes are grown with a catalyst and preserved in a fluid, which the end user must go through several steps to remove. The nanotubes described here can be grown and then directly attached to the array surface.
Because large numbers of nanotubes are needed to generate current efficiently, they are attached in a dense, but random arrangement. After the nanotubes are deposited on the surface, the metallic contacts from which the current is gathered are applied in a uniform grid over the nanotubes.
The invention also includes a novel method of manufacturing the nanotube array. Normally, nanotubes are grown with a catalyst and preserved in a fluid, which the end user must go through several steps to remove. The nanotubes described here can be grown and then directly attached to the array surface.
Because large numbers of nanotubes are needed to generate current efficiently, they are attached in a dense, but random arrangement. After the nanotubes are deposited on the surface, the metallic contacts from which the current is gathered are applied in a uniform grid over the nanotubes.
KEY BENEFITS
- Significantly higher efficiency than current technologies
- Relatively inexpensive to manufacture
- Potentially able to compete with commercial sources for generating power
- Carbon nanotubes are flexible and may be placed on a polymer support to reduce production costs
- Avoids the need for expensive silicon processing environments
- Useful to power a variety of devices, including computers, mobile phones, calculators, and watches
- Useful to generate power in a power grid
For current licensing status, please contact Wisconsin Alumni Research Foundation team at licensing@warf.org or phone 608.262.4924.
