The new study, conducted by Christopher Bielawski and Jonathan Sessler, tries to improve the way electrons move back and forth between two molecules, since this event creates electricity. Moreover, it might be a necessary step toward creating artificial photosynthesis, where fuel could be generated directly from the sun, much as plants do.
According to previous studies, the exchange of electrons between molecules often form new compounds. In some cases, the electron transfer process creates one molecule with a positive charge and one molecule with a negative charge. Molecules with opposite charges are attracted to each other and can combine to form something new.
In this latest study, published in Science, the chemists produced two molecules that could meet and exchange electrons – but not unite to form a new compound. “These molecules were effectively spring-loaded to push apart after interacting with each other,” explained Bielawski. “After electron transfer occurs, two positively charged molecules are formed which are repelled by each other, much like magnets held in a certain way will repel each other. We also installed a chemical switch that allowed the electron transfer process to proceed in the opposite direction.”
The new system gives the ability to create efficient organic battery. By understanding the electron transfer processes in these molecules, the team could design organic materials for storing electrical energy that could then be retrieved for later use. While similar plans were made in the past, other researchers lacked the ability to manipulate electron flow. “This is the first time that the forward and backward switching of electron flow has been accomplished via a switching process at the molecular scale,” said Sessler.
The paper defines organic batteries by likening it to regular batteries; however, instead of heavy metals, organic materials are used. They are lightweight, can be molded into any shape, have the potential to store more energy than conventional batteries, and are safer and cheaper to produce. Thanks to the development of the molecular switch, the team can ensure the electron movement will create electricity. “I am excited about the prospect of coupling this kind of electron transfer ‘molecular switch’ with light harvesting to go after what might be an improved artificial photosynthetic device,” says Sessler. “Realizing this dream would represent a big step forward for science.”
Aside from improving battery technology, the research might help develop technology that mimics plants’ ability to harvest light and convert it to energy. With such a technology, fuel could be produced directly from the sun, rather than through a plant mediator, such as corn.
The most exciting application of the new development, however, is creating smaller, lighter, and more efficient batteries. “I would love it if my iPhone was thinner and lighter, and the battery lasted a month or even a week instead of a day,” says Bielawski. “With an organic battery, it may be possible. We are now starting to get a handle on the fundamental chemistry needed to make this dream a commercial reality.”
The team collaborated with several scientists from multiple institutions, but they wish to specially credit graduate student Jung Su Park, for his detailed work growing crystals of the two molecules. Their next step is to demonstrate these processes can occur in a condensed phase, like in a film, rather than in solution.
TFOT also covered the production of solar energy using an ”artificial leaf,” and an air-fueled battery, studied at the University of St. Andrews.
For more information about these new high-powered organic batteries, see the official press release, published by University of Texas.