3.4 ns, indicating a different species as compared to the 660 nm ESA. In DCM (Figure , Supplementary Fig. ), ESA at 670 nm emerges within 700 fs, followed by ESA at 870 nm ΔT/T ( For p-ICz-PI, the hole is primarily localized over the single phenyl ring of the tert-Cz unit, with some contribution existing in the PI unit (Figure , Supplementary Fig. -26 and Supplementary Table ). The electron is delocalized over the remaining fragment of the molecule that consists of both the tert-Cz and PI units. This configuration results in a very weak "donor" unit, contributing little CT character to the excited state, thus the emission is blue and exhibits predominantly locally-excited (LE) character. In contrast, o-ICz-PI exhibits a hole that is primarily localized over the whole ICz unit, while the electron is concentrated over the PI unit. This arrangement resembles that of Cz-PI, which itself shows even stronger CT character because of the 90 twist between D and A at the N-C bridging bond.