Posted: February 17, 2010

Scientists boost solar cell efficiency with quantum dots

(Nanowerk News) A German team of scientists has developed a technique to treat nanoparticle surfaces. This treatment boosts the efficiency of organic solar cells. Presented in the journal Applied Physics Letters, the work shows how 2% efficiency was obtained by using so-called quantum dots made up of cadmium selenide.
The researchers from the Institute of Microsystem Technology (IMTEK) and the Freiburg Materials Research Center (FMF), both at the University of Freiburg in Germany, succeeded in breaking the previously held efficiency ratings of between 1% to 1.8%. The method is protected by patent.
The 'Dye and Organic Solar Cells' research group at Fraunhofer Institute for Solar Energy Systems in Germany confirmed the measurements made by the Freiberg scientists.
According to the team, hybrid solar cells are protected by a layer containing a mixture of inorganic nanoparticles and an organic polymer. From a theoretical perspective, the new technique can be used on many nanoparticles, and could further fuel the efficiency of this type of solar cell.
Still in the developmental phase, organic solar cells are part of the third generation of solar cells, the scientists said. Latest data show that the world record for purely organic solar cells stands at 7% for layers created through wet chemical methods. The photoactive layer of these organic solar cells is made up of organic materials.
The energy market would benefit immensely from organic solar cell use. Energy producers commonly use conventional silicon cells, but solar cells are significantly thinner, more flexible, cheaper and quicker to produce.
The scientists said organic solar cells can be used to strengthen everyday devices and systems that are not used consistently including electrical appliances. Ultimately, organic solar cells could be used to significantly decrease people's dependence on batteries and cables.
'The interdisciplinary orientation of the group is a clear advantage and has led to rapid progress on the project,' explained IMTEK's Dr Michael Kr├╝ger, who led the group. 'We were able to carry out all of the steps on our own: from the synthesis of the nanoparticles to the modification of their surface and integration into composite materials.'
The research group comprises physicists, chemists and engineers. They are currently applying the technique to other materials with a lot of potential so as to refine them further and get them ready for a technology market launch. Commercialisation of the technique is dependent on better efficiency, improved durability of the materials, and cheaper production costs.
Source: Cordis