Design principles for efficient singlet fission in anthracene-based organic semiconductors

Singlet fission (SF) in two or more electronically coupled organic chromophores converts a high-energy singlet exciton into two low-energy triplet excitons, which can be used to increase solar cell efficiency. Many known SF chromophores are unsuitable for device applications due to chemical instability and low triplet state energies. This work summarizes structurally dependent SF dynamics for 9,10-bis(phenylethynyl)anthracene (BPEA) and its derivatives in the solid-state using time-resolved optical spectroscopies, and electronic structure calculations. By modulating the packing structure in thin films, we can effectively tune electronic energy and coupling. The systematic study in BPEA organic semiconductors shows that maximizing the thermodynamic driving force can achieve the highest SF rate and efficiency.