Solar energy storage taken to next level
30 Jul 2015 by qwbdchbctt.d qwbdchbctt.d
Chemists at UCLA have developed technology that can store solar energy for up to several weeks rather than for a few microseconds.
Inspired by the way plants generate energy, the scientists used uniquely designed polymers and fullerene molecules that can convert photon energy from sunlight into positive and negative electric charges and store them for weeks.
“In photosynthesis, plants that are exposed to sunlight use carefully organised nanoscale structures within their cells to rapidly separate charges – pulling electrons away from the positively charged molecule that is left behind, and keeping positive and negative charges separated. That separation is the key to making the process so efficient,” said Professor Sarah Tolbert at UCLA.
In the study, published in Science, the researchers used polymers that donate electrons when photon energy is absorbed and fullerene molecules that accepted the electrons. They arranged the polymers and fullerene molecules in a way that some fullerenes sat inside a polymer structure, and others were forced to sit outside that structure. When the polymers absorbed photon energy, the fullerene molecules inside the structure accepted the donated electrons and transferred them to the outside fullerenes.
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Credit: UCLA[/caption]
“Modern plastic solar cells don’t have well-defined structures like plants do because we never knew how to make them before. But this new system pulls charges apart and keeps them separated for days, or even weeks. Once you make the right structure, you can vastly improve the retention of energy,” said Professor Tolbert.
At this stage the researchers have only developed the technology on a test tube level. They are planning to incorporate the technology into actual solar cells.
Professor Yves Rubin who led the study said: “We don’t have these materials in a real device yet; this is all in solution. When we can put them together and make a closed circuit, then we will really be somewhere.”
