City University of New York
Faculty Host: Sahar Sharifzadeh
Student Host: Aliya Mukazhanova
Refreshments at 2:45 PM
Multiple exciton generation in isolated organic molecules
Singlet fission is a form of multiple exciton generation (MEG) in which two triplet excitons are produced from the absorption of a single photon. However, practical implementations of organic MEG have been limited by the small number of organic chromophores that undergo efficient singlet fission, largely restricted to molecular crystals of oligoacenes. In these materials, the singlet fission process is highly sensitive to crystal packing and morphology, hindering the design of efficient triplet harvesting interfaces and the development of high throughput device processing strategies. In this talk, I will discuss our recent discovery of efficient intramolecular singlet fission materials, in which two triplets are produced on an isolated molecule and in which geometric order and strong nearest neighbor coupling is no longer a design constraint. These materials, which include both small molecules and polymers, have expanded the quantity and variety of materials that undergo singlet fission and offer significant advantages in terms of their tunable molecular and electronic structure, solution processability, and the ability to form tailored interfaces. In addition, they offer a unique platform in which to study the dynamical evolution of multiexciton states, since the system can be constrained such that exactly two triplets exist on the molecule. I will discuss structure-function relationships that promote the fast formation of triplet pairs followed by dissociation into free triplets and discuss implications for device applications.
Matt Sfeir is an Associate Professor in Physics and the ASRC Photonics Initiative at the City University of New York. He joined CUNY in January from the U.S. Department of Energy’s Brookhaven National Laboratory. As part of the laboratory’s Center for Functional Nanomaterials, his work focused on enabling technologies for next-generation optoelectronic devices. He has received numerous awards for his work in photophysics, and in 2018 was named an “Inventor of the Year” by the global science and technology organization Battelle.