Jan 18 2011
Researchers at the Purdue University are trying to create a new type of solar cell, which would be able to self-repair similar to natural plant systems by using DNA and nanotubes. This would not only increase service life but also reduce its cost.
According to Jong Hyun Choi, who is an assistant Professor of Mechanical Engineering at the Purdue University, artificial photosystems that utilize optical nanomaterials for harvesting solar energy, which would then be converted into electricity have been created. The design takes advantage of the remarkable electrical properties of structures termed as single-wall carbon nanotubes and uses them as molecular wires inside the light harvesting cells. His research group was based at Purdue’s Discovery Park’s Birck Nanotechnology and Bindley Bioscience Centers. He felt that this could be commercialized but currently it was still in the research stage.
Photoelectrochemical cells transform sunlight into electricity using an electrolyte for conducting the electricity so that electrons could be transported and current could be created. The cells include dyes, which are capable of light absorption called chromophores. These chromophores are chlorophyll like molecules, which degrade when exposed to sunlight and this degradation is the main disadvantage for the conventional photoelectrochemical cells. The new technology has conquered this problem by replacing continuously the photo damaged dyes with new dyes just as nature does. In plants this self regeneration takes place every hour. Hence this device could probably be the answer to the conventional photoelectrochemical cell and would operate at full capacity for ever as long as new chromophores are added. The research findings were revealed in a presentation during the International Mechanical Engineering Congress and Exhibition in Vancouver in November 2010. It was also made public in an online article, which was uploaded on the SPIE website. Both the article and talk were authored by Choi and undergraduate students Yujun Wu and M. Dane Sauffer and doctoral students Tae-Gon Cha and Benjamin A Baker.
Choi further mentions that the carbon nanotubes act as a platform anchoring the DNA strands. The DNA is designed to include specific sequences of nucleotides, which are the building blocks. This would help them in recognizing and attaching to the chromophores. After recognizing the dye molecules the DNA spontaneously self assembles. When the chromophores have degraded and are ready to be replaced they could be removed by employing chemical processes, or even new DNA strands could be added with entirely different nucleotide sequences and the damaged dye molecules could be eliminated. After which new chromophores would be added. Molecular recognition and thermodynamic metastability are two vital elements of this technology.
This research was actually an extension to the collaboration work done by Choi and other researchers at the University of Illinois and the Massachusetts Institute of Technology. Prior to this they had used biological chromophores from a bacteria and this research had been published earlier in the Nature Chemistry, a journal. Choi stated that using natural chromophores were very difficult as harvesting and isolating it from the bacteria was an expensive and difficult process and not commercially viable. Hence he used synthetic ones made from dyes called porphyrins instead of biological chromophores.