A porous van der Waals single-crystal of aromatic dendrimer exhibiting enhanced thermally activated delayed fluorescence

Abstract

Here we report the single crystal structure and enhanced thermally activated delayed fluorescence (TADF) properties of a porous van der Waals crystals of G3TAZ, a 3rd-generation aromatic dendrimer composed of a triazine core (TAZ) and carbazole (Cz) dendrons. Single-crystal structural analysis by electron diffraction reveals that the crystal forms solely via multiple van der Waals forces and possesses micropores with a pore limiting diameter of 6.40 Å and a maximum pore diameter of 8.85 Å. G3TAZ is the largest molecule (3,778 Da) ever reported that can build up a van der Waals crystal with extrinsic porosity. The crystal exhibits a hydrogen uptake of 0.73 wt% at 298 K under 11.5 MPa. The orthogonal conformation of the Cz dendrons to TAZ core in the crystalline state facilitates TADF efficiency, which accounts for 72% of the total emission at 150 K. This value is significantly higher than those in the amorphous state, such as microspherical particles and cast films.