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 1 LE and 1 CT 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.