Design of Singlet Fission Chromophores through the Introduction of N-Oxyl Fragments.

Singlet fission is a highly desired phenomenon in photovoltaics. In the fission process, one short-lived singlet exciton splits to two long-lived triplet excitons. Generating a larger number of longer-lived excitons, singlet fission has the potential to enhance the photoelectric conversion efficiency. The exploitation of this phenomenon in the photovoltaic industry is however impacted by the small pool of existing singlet fission chromophores. Here, we report on the design of novel singlet fission chromophores through the substitution of N-oxyl fragments within the anthracene framework. The substantial diradical character brought on by the N-oxyl fragments located at specific positions on the anthracene pristine structure together with structural reorganization induced by excitation allows for a handful of chromophores to satisfy the thermodynamic requirements of singlet fission.