Fluorescence and Phosphorescence Anisotropy from Oriented Films of Thermally Activated Delayed Fluorescence Emitters.

Anisotropy within three TADF materials has been observed using steady-state fluorescence polarization. This technique has allowed for the observation of differences in polarization within dilute solution, and both unstretched and stretched films; the latter producing highly aligned molecules within the sample. Using these aligned films differences in anisotropy can be observed between the emission from the 1LE and 1CT states and upon exciting different absorption bands. Furthermore, polarization observed from time-resolved measurements highlights the strong vibronic coupling between charge-transfer and local triplet states.