Design of singlet fission chromophores by the introduction of N-oxyl fragments.

Singlet fission is a highly desired process in organic photovoltaic devices. It splits one singlet exciton into two triplet excitons and enhances the power-conversion efficiency. However, the exploitation of this process in photovoltaic devices is plagued by the small number of singlet fission chromophores. In this work, we designed a series of singlet fission chromophores by introducing N-oxyl fragments into anthracene. The diradical character brought by the N-oxyl fragments and the structural reorganizations in response to excitation to the lowest triplet state allow some of the investigated molecules to satisfy the thermodynamic energy criteria for singlet fission chromophores.