As seen in zeonex, the TADF behavior of both AZB-Ph-TRZ and AZB-TRZ varies considerably when dispersed in small-molecule hosts mCP and DPEPO. The emission decays of each emitter:host combination is strikingly different, both when comparing the two emitters in the same host, and comparing a single emitter in each of the three different environments. For both materials, the DF intensity is lower and the DF emission is longer-lived in DPEPO than in mCP. There is also a notable long-lived secondary DF component for AZB-TRZ in mCP, distinct from the initial rapidly decaying DF. We have recently demonstrated how the flexibility of some D-A bridging bonds can lead to large conformational distributions of molecular geometries in solid films, with subsets of molecules possessing different TADF properties (especially decay times). Similar to the different contributions to the steady-state emission in zeonex, we suggest that this secondary DF component arises from a subset of AZB-TRZ molecules in an unfavorable conformation in the film, with corresponding long-lived emission. To reveal the nature of the triplet states in these two derivatives, time-dependent emission measurements were performed at 80 K to measure the phosphorescence emission (PH) and determine the energy of the T1 state. We observed a substantial red-shift in the delayed emission spectra of AZB-Ph-TRZ at long delay times (~80 ms) in 1 wt% doped zeonex films, which we interpret as the emergence of the PH spectrum (Figure ). Significantly reduced delayed emission intensity was observed for AZB-TRZ along with PH emission at very long delay times at 80 K (Figure ). The PH spectrum of AZB-TRZ is only subtly different from the emission of the PF or DF, but the emergence of the differently structured emission allows us to attribute it as belonging to an 3 LE state nonetheless.