We use MRSF-TDDFT and NEVPT2 methods to design singlet fission chromophores with
the building blocks of cyclic (alkyl)(amino) carbenes (CAACs). CAAC dimers with C 2, C 4,
and p-phenylene spacers are considered. The substitutions with trifluoromethyls and
fluorine atoms at the α C position are investigated. The electronegative substituents
enhance the π accepting capability of the α C while maintaining it as a quaternary C atom.
The phenylene-connected dimers with the two substitutions are identified as promising …