In all the above molecules the intruding triplet state is much lower energy (in most cases ∼ 1 eV) than the triplet state with the same electron configuration as S 1 . In s-indacene the HOMO-1 and HOMO are near-degenerate which allows for fine-tuning of the excited state ordering with substituents. Still, in most cases the substituents we have used here do not change the frontier MO eigenvalues sufficiently to affect the state ordering.