Lightweight as a window cling and replicable as a newspaper, organic solar cells are emerging as a viable solution for the nation’s growing energy demand.
Researchers at the University of Illinois Urbana-Champaign are the first to observe a biological property called chirality emerging in achiral conjugated polymers, which are used to design flexible solar cells. Their discovery could help enhance the
cells’ charge capacity and increase access to affordable renewable energy.
DNA’s coiled architecture is recognizable to many as a helix. Structurally speaking, DNA and other helical molecules are classified as chiral: asymmetrical such that superimposition onto a mirror image is impossible. The term originates with the Greek word for hand, which is also an example. Picture a left handprint on a sheet of paper, followed by a right handprint directly on top. The two prints do not neatly align; your hand, like its DNA, is chiral.
From hands and feet to carbohydrates and proteins, chirality is twisted into humans’ genetic makeup. It’s also abundant in nature and even enhances the chemical reaction that drives photosynthesis.
“Chirality is a fascinating biological property,” said Ying Diao, an associate professor of chemical and biomolecular engineering and the study’s principal investigator. “The function of many biomolecules is directly linked to their chirality. Take the protein complexes involved in photosynthesis. When electrons move through the proteins’ spiraled structures,
an effective magnetic field is generated that helps separate bound charges created by light. This means that light can be converted into biochemicals more efficiently.”
For the most part, scientists have observed that molecules of like structures tend to keep to themselves: chiral molecules assemble into chiral structures (like nucleic acids forming DNA), and achiral molecules assemble into achiral structures.
Diao and her colleagues observed something different. Under the right conditions, achiral conjugated polymers can depart from the norm and assemble into chiral structures.
Their paper appears in Nature Communications and introduces new opportunities for research at the convergence of biology and electronics. For the
first time, scientists can apply chiral structure to the myriad materials that require achiral conjugated polymers to function.
In particular, solar cells: paper-thin solar panels scaled down to the size of a computer screen. Composed entirely of organic materials, the flexible cells are transparent and lightweight enough to cling …….