Conversion of Solar energy into Electrical and Mechanical Energy using Carbon Nanotubes
University of Louisville, US
Keywords: nanotube, solar energy, strain
Abstract:Conversion of solar energy into one or more forms of energy is an important priority today. The earth receives 170 petwatts of solar radiation. 30% is reflected into space and the rest is absorbed by the earth. Most of the solar radiation falls in the visible to near infra-red region of electromagnetic spectrum with a small amount in the ultra-violet region. Today most nanomaterials based energy conversion focuses on converting solar energy into electrical energy. However, one could envision smart structures if we could convert solar energy into many other types of energy. In this paper we show the direct conversion of solar energy into electrical and mechanical energy using carbon nanotubes. The high optical absorbance of carbon nanotubes in the 700-1100 nm of the electromagnetic spectrum lends itself for solar cell applications. Further, the mechanical actuation of nanotubes in this same region of the spectrum brings us to important cross roads of converting solar energy into mechanical and electrical energy. This is possible only in nanomaterials such as carbon nanotubes due to the multiple physics at the nanoscale. Preliminary investigations show that nanotubes could undergo mechanical actuation with strains 0.1-0.3% comparable to piezoelectric materials using solar energy. Further, investigations into the photoconductivity of carbon nanotubes showed electron-hole pairs that show that mechanical actuation is coupled with electronic transitions in carbon nanotubes.