A new arrangement of familiar chemical materials could improve the efficiency of cheap solar panels, thanks to a significant increase in the ability of these materials to absorb the sun's energy and release it as electricity.
[Translation by Dr. Nachmani Moshe]
![Scientists have succeeded in developing a new and particularly efficient arrangement of components in a solar cell, where the charge donors are bundles of polymer (in green) and the charge acceptors are spherical carbon molecules, fullerenes (in purple and brown). [Courtesy of UCLA]](https://www.hayadan.org.il/images/content3/2015/07/Figure_4E_green_polymer1-500x460.jpg)
A new arrangement of familiar chemical materials could improve the efficiency of cheap solar panels, thanks to a significant increase in the ability of these materials to absorb the sun's energy and release it as electricity.
A team of scientists from the University of California, Los Angeles, discovered that by arranging the components of the solar panels in a manner more similar to the arrangement existing in natural systems that utilize sunlight, it is possible to separate the positive and negative charges stably for a long time of up to several weeks, compared to a time of a millionth of a second - the rate that exists today in many of the modern solar panels.
"In the process of photosynthesis, plants exposed to sunlight utilize specially arranged nanostructures found inside their cells to quickly separate charges - while pulling the electrons out of the molecule to obtain a positive charge and maintaining their separation over time," said Sarah Tolbert, professor of chemistry at UCLA and one of the principal researchers . "This separation is the key to making this process efficient." X-ray crystallography studies carried out by the researchers allowed them to see, at the microscopic level, what is the optimal arrangement of the nanostructures that encourages the separation of the charges over time. The research findings were recently published in the prestigious scientific journal Science.
In order to capture energy from the sun's rays, ordinary solar cells located on the roofs of buildings are based on the material silicon, which is an expensive material. Normal solar cells can also be made from cheaper materials, such as plastic, but these are less efficient - largely due to the fact that the separated charges in the material quickly re-fuse before they are converted into electrical energy. "Modern plastic solar cells do not include highly organized structures, such as those found in plants, because until today we did not know how to build them," said the lead researcher. "However, our new system separates the opposing charges and leaves them in this state for several days, and even for several weeks. Once you have developed the appropriate structure, you can significantly improve energy conservation."
The researchers developed a system consisting of coils of polymer, which are the building blocks of plastic, that absorb the sun's rays and transfer electrons to the fullerene (Wikipedia), A spherical carbon molecule also known as a "bucky ball". The materials that make up these types of solar cells are usually organized in a way similar to that of a cooked pasta dish - a disordered mass of thin and long polymer coils ("spaghetti") together with spherical fullerene molecules that are randomly organized ("meatballs") above them. However, such an arrangement is problematic in terms of receiving a current from the cell since the electrons, sometimes, jump back to the polymers and cause the loss of the electric current.
The researchers were able to organize the system components in a more orderly manner - small packages of spaghetti next to which are meatballs in precise positions. The system was designed so that some of the fullerenes are integrated inside the polymer packages and others are forced to remain outside them. The fullerenes inside the structure extract electrons from the polymers and transfer them to the outer fullerenes, which enables efficient preservation of the electrons separated from the polymer for weeks. Many experiments have proven that this arrangement is the most effective. "When the charges never fuse back, it becomes easier to get them out of the solar cell in the form of electricity," says one of the researchers. "This is the first time that such long durations of charge separation using such types of materials have been demonstrated."
The researchers found that the materials organize themselves into this arrangement when they are brought close to each other. The new arrangement is also more environmentally friendly compared to existing technologies, this is in light of the fact that the materials are organized in water, instead of in toxic organic solutions that are widely used today. "Once you have prepared the materials, you can simply throw them into water and they will organize themselves to obtain the appropriate structure thanks to their design," said one of the researchers.
One response
There is no doubt that solar energy storage is effective
There will be a breakthrough for the reduction of energy on earth.