Want to improve the efficiency of solar cells? Just play rock! That is exactly what scientists from Queen Mary University of London and Imperial College London have recently reported in their paper titled “Acoustic Enhancement of Polymer/ ZnO Nanorod Photovoltaic Device Performance”.
Essentially these scientists grew nano rods from Zinc Oxide. They covered these tiny rods (billions of them) with a polymer thereby creating a solar cell and then the boom box was brought into action. Music was played and, as a result, cell performance increased. With rock and pop music accompanying the solar-electric tango, the efficiency enhancement soared to 40%! A big jump indeed.
Interestingly sound levels as low as 75 dB (typical roadside noise level) was found to be effective.
The secret of this lies in a phenomenon long known to the scientist called piezoelectric effect. Certain materials have this exciting property to convert stress or pressure applied to them into electricity. The noise, being mechanical waves traveling through air as compressions and rarefactions, exerted small pressure on the material of the solar cell. The material, exhibiting piezoelectric phenomenon, converted them to electrical voltage thereby enhancing the efficiency of the cell. As rock and pop music has big beats, the pressure exerted on the solar cell was large and hence resulted in greater efficiency gains.
Initially the researchers were a bit skeptical thinking that the randomness of the stress due to the randomness in music might result in mutual cancellation of the electric voltages so generated. But experimentation proved the apprehensions wrong and the braves came out victorious squeezing 40% more from the same sun.
This newly discovered process of combining piezoelectric and photovoltaic phenomena could be used in solar cells exposed to ambient noise. Air conditioning units, automobiles, office printers, etc., are good sources for adding a dash of piezoelectric to this solar-piezo mix.