However, the ESAs of T1 are more important due to the longer-lived nature of the triplet states. After ISC is completed by 100 ns, all materials possess a weak T1 ESA band that overlaps with the GSB edge at 460 nm with a second lower energy band located towards the edge of the probe region at 800 nm. Whilst there is also some overlap of the higher energy T1 ESA with the SE band of the emitters, we note that this ESA band begins to decrease in intensity around 500 nm. This suggests that efficient lasing with minimal parasitic T1 ESA losses may be achieved towards the lower energy edge of the SE band, especially for 4tCzPz which possesses the reddest emission of the three studied compounds.