Transitioning to solid hosts, the PL spectra (Figure ) and decays (Figure ) of AZB-Ph-TRZ and AZB-TRZ were investigated in zeonex and two high triplet energy OLED-compatible hosts: mCP and DPEPO. In 1 wt% doped zeonex films, AZB-Ph-TRZ at 300 K shows very longlived and weak delayed fluorescence (DF), having two main components with the same spectrum across all of the DF in addition to the short-lived prompt fluorescence (PF, individual spectra shown in Figure ). The emission is itself very narrow, indicative of 1 LE excitons as was observed in toluene. In comparison, AZB-TRZ shows much stronger DF with considerably shorter DF lifetimes, along with a longer-lived PF (individual spectra shown in Figure and fitted exponential lifetimes and rate constants in Table ). The steady-state PL spectrum is broad but slightly structured, while being gaussian-shaped in the time-resolved spectra, which we interpret as a mixture of molecules in the film contributing to the steady-state emission; some with predominantly 1 CT DF alongside others emitting with 1 LE character PF. This mixture of LE character emission in both materials reflects the weakness of the AZB donor as well as the nonpolar zeonex host being unable to strongly stabilize CT states. To account for this mixture, experimental singlet energies are taken from the onsets of the relaxed PF emission spectra (Figures ), allowing us to avoid the LE emission component in determining these values (Table ).