2021 Theses Doctoral

Singlet Fission: A Twisted Tale

Conrad-Burton, Felisa

In the past decade, research in the field of singlet fission, the process in which one high energy singlet fission exciton forms two lower energy triplet excitons, has seen a resurgence as a process that has the potential to improve solar energy conversion efficiency and contribute to a push for renewable energy. While an impressive motivation, there is still much progress in terms of understanding the physics of the process as well as improving molecular design for actual applications that needs to be made before this motivation can be fully realized. Two significant current hurdles in this field are the extraction of the newly formed triplet excitons from their entangled triplet pair state before recombination, and the lack of stable chromophores with viable energetics for singlet fission and high triplet energies for application purposes.

Over the past five years, we have addressed these issues with targeted molecular design. Only a couple of studies have successfully separated the triplet pair state in intramolecular singlet fission systems. We create an intramolecular singlet fission system, a PDI-pentacene-pentacene-PDI tetramer, in which a charge transfer state is utilized to separate an electronically entangled triplet pair. We have also shown that singlet fission can be controlled as well as actually induced in chromophores by employing molecular contortion to tune the energetics. With this work, we have contributed to the motivation of using singlet fission in real-life applications.