Scientists have invented a new method of arranging the components of solar cells. The green bars in the picture are polymer donors, and the purple and brown ones are fullerene acceptors.

Currently, solar panels on residential roofs can only store a few microseconds of solar energy at a time. A new technology invented by chemists at the University of California, Los Angeles can store solar energy for several weeks-a major development that can change the design of solar cells. The results of this study were published in the journal Science.

The new design is inspired by the photosynthetic use of plants. "The way organisms use sunlight to generate energy is great." One of the authors of the article, UCLA Professor of Chemistry Sarah Tolbert explained, "Plants use very high efficiency for photosynthetic purposes to convert solar energy." "In photosynthetic purposes, receive Sunlit plants use finely organized nano-scale organelles to separate charges-pull electrons from positively charged molecules and separate positive and negative charges." Tolbert said, "This separation process is highly efficient photosynthesis. The key to its use. "General rooftop solar cells use silicon, a relatively expensive material, to obtain energy from sunlight.

At present, plastic is used to make the driving force of cheap batteries. However, since the separated positive and negative charges are recombined before outputting electric energy, the current plastic solar cells are not efficient. "Current plastic solar cells do not have the fine structure of plants, because we have no relevant manufacturing experience before." Tolbert said, "but we designed this new system to separate positive and negative charges within days or even weeks. Once you get the structure right, you can greatly extend the energy storage time." The new system made by UCLA plays an important role in a polymer donor and a nano-level fullerene receptor. body.

The polymer donor can absorb sunlight and transfer electrons to fullerenes, and electrical energy appears in this process. The structure of plastic materials called organic photovoltaics is usually as disordered as a plate of cooked pasta. The elongated polymer donor is like "spaghetti" and fullerene is like "meatball". This structure makes it difficult for current to flow out of the battery, because sometimes electrons will bounce back to the polymer "pasta" and then disappear. The new technology arranges these ingredients in an orderly manner—just like a handful of business faces and meatballs that are precisely interspersed in it. Some fullerene "meatballs" are surrounded by the polymer donor, while others are on the outside. The surrounding fullerene separates the electrons from the polymer and then "throws" to the outer fullerene.

In this way, electrons can leave the polymer for several weeks. "When the charge does not return, the system works well." Another author of the article, Benjamin Schwartz, a professor of chemistry at the University of California, Los Angeles, explained, "This is the first time this is done with synthetic organic photovoltaic materials." In the system, as long as the materials are put together, they can complete self-assembly. "We really worked hard to design this new system so that we don't have to work hard in the future." Tolbert said that the new design is more environmentally friendly than the current general design because the material can be carried out in water instead of the toxic organic solvents currently used. Assembly. "Once you can make this material, you can pour them into the water, and they will assemble themselves into a suitable structure because they are designed this way," Schwartz said, "so no additional work is required." People have begun to study how to apply this new technology to current solar cells.

Another author of the article, Yves Rubin, a professor of chemistry at the University of California, Los Angeles, commented: "We have not tested this material in real solar equipment. But the solution is all here. If we can assemble them into one When we close the circuit, we are really successful." But for now, these scientists have shown that cheap photovoltaic materials can be organized in some way to greatly improve the ability to store solar energy.