Researchers at Louisiana Tech University have come up with a so-called energy cell that scavenges light and thermal energy from sources such as integrated circuits. The device consists of a carbon nanotube film integrated with a lead zirconate titanate cantilever. Illumination by light and thermal radiation generates an electric potential of 10 V, researchers say. Experiments thus far show that the device can generate 2.1 microwatts of power at a light intensity of 0.13 W/sq-cm, which is enough to operate some low-power sensors and ICs.
The lead zirconate titanate is piezoelectric material – material capable of converting distortions to itself into electrical energy. The cantilever made with the PZT is coated with a carbon nanotube film on one side. When the film absorbs light and/or thermal energy, it makes the cantilever bend back and forth repeatedly, which causes the piezoelectric material to generate power.
Researchers say their cantilever technology can also harvest different types of energies such as vibrational and wind energies. In operation, each carbon nanotube absorbs and converts photon energy into thermal and electrostatic energy. Temperature rise of the carbon nanotube coupled with its high thermal conductance raises the temperature of the carbon nanotube film so that it expands and bends the cantilever.Specifically, light hitting the film produces a nonuniform charge distribution in the flm because of electon-hole pair generation in the carbon nanotubes. This results in the formation of an electrostatic field which makes the film expand and thus bend the cantilever.
The paper titled, “Light and thermal energy cell based on carbon nanotube films” and co-authored by Dr. Long Que, assistant professor of electrical engineering, and students Pushparaj Pathak, Tianhua Zhang, Yuan He, and Shashi Yadav, was published in the September edition of Applied Physics Letters.