EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

А successful tactic for contravention of the theoretical limit on the solar cells efficiency is the implementation of photoactive materials prone to singlet fission (SF)[1]. The first documented singlet fission material – anthracene, was accredited in 1963 but it turned relatively inefficient due to the small size of its conjugated system. About half a century later, it was shown that efficient singlet fission chromophores are the larger acenes: tetracene and pentacene. Lately, the molecular design in the SF field outspreads beyond acenes and new classes of SF chromophores, based on conjugated polymers/oligomers, carotenoids, and carbenes, were suggested [2]. Notwithstanding, the amount of molecules capable of singlet fission is unassuming and the structure-property correlation in such materials is underinvestigated.
This theoretical study addresses N-containing heterocyclic carbene dimers as potential SF materials. The treatment utilizes the newly developed simplified spin-flip formalism of the time dependent density functional theory [3]. All compounds are modelled for the first time in our laboratory; they are synthetically attainable and have potential for application in solar cells. The study gives insight into the effect of different factors, such as topology, conformation, conjugation size, and substituent position, on the singlet fission propensity. Several new prospective singlet fission materials are suggested.
The study is supported by the National Research Program E+, grant D-01-214/2018, and Project ML4SF, grant КП-06-Н39/2/2019.
References:
[1]. M. B. Smith and J. Michl, Chem. Rev. 2010, 110, 6891–6936.
[2]. D. Casanova, Chem. Rev. 2018, 118, 7164–7207.
[3]. M. de Wergifosse, C. Bannwarth and S. Grimme, J. Phys. Chem. A 2019, 123, 5815−5825; https://github.com/grimme-lab/stda.