Researchers at the University of Missouri-Kansas City (UMKC) and the University of Florida (UF) have pioneered a method to tease out promising molecular structures for capturing energy, a step that could speed the development of more efficient, cheaper solar cells.
“This gives us a new way of studying light-matter interactions,” said Valeria Kleiman, a UF associate professor of chemistry and lead author of a paper featured in a recent issue of the journal Science. “It enables us to study not just how the molecule reacts, but actually to change how it reacts, so we can test different energy transfer pathways and find the most efficient one.”
Co-investigators include Zhonghua Peng, UMKC professor of chemistry, and Daniel Kuroda and C.P. Singh at the University of Florida.
The research team’s work focuses on molecules known as dendrimers, which have many branching units that make them good energy absorbers.
“A number of such dendrimers have been reported, but our dendrimers are unique in that there are different branches, some short and some long, just like a tree with a trunk and branches of various lengths,” Peng said. “Such a structure offers the absorbed energy various pathways.”
The amount of energy the synthetic molecules can amass and transfer depends on which path the energy takes as it moves through the molecule. The UMKC and UF researchers are the first to gain control of this process in real time. The team demonstrated that it could use phased tailored laser pulses — light whose constituent colors travel at different speeds — to prompt the energy to travel down different paths.
“What we see is that we control where the energy goes by encoding different information in the excitation pulses,” Kleiman said.
Researchers who now test every new molecular structure for its energy storage and transfer efficiency may be able to use what Kleiman called a new spectroscopic tool to quickly identify the most promising structures for photovoltaic devices.
“We are continuing to design new dendrimers with more efficient light-harvesting properties. Such dendrimers have promising potential as ultrasensitive molecular sensors and solar cells,” Peng said.
This research was supported by UF and the National Science Foundation (NSF). Peng’s research on dendrimers has been supported through the years by the Defense Advanced Research Project Agency (DARPA), the Office of Naval Research (ONR) and NSF.
The University of Missouri-Kansas City (UMKC), one of four University of Missouri campuses, is a public university serving more than 14,000 undergraduate, graduate and professional students. UMKC engages with the community and economy based on a four-part mission: life and health sciences; visual and performing arts; urban issues and education; and a vibrant learning and campus life experience.