Capturing the Interplay Between TADF and RTP Through Mechanically Flexible Polymorphic Optical Waveguides.

Polymorphism plays a pivotal role in generating a range of crystalline materials with diverse photophysical and mechanical attributes, all originating from the same molecule. Here, we showcase two distinct polymorphs: green (GY) emissive and orange (OR) emissive crystals of 5'-(4-(diphenylamino)phenyl)-[2,2'-bithiophene]-5-carbaldehyde (TPA-CHO). These polymorphs display differing optical characteristics, with GY exhibiting thermally activated delayed fluorescence (TADF) and OR showing room temperature phosphorescence (RTP).