Relationship between molecular structure and dipole orientation of thermally activated delayed fluorescent emitters

Abstract The relationship between the chemical structure and the dipole orientation of thermally activated delayed fluorescent (TADF) emitters was examined by synthesizing three TADF emitters with donor and acceptor moieties at ortho-, meta-, and para-positions of a phenyl linker. Two carbazolylcarbazole donor moieties and two CN acceptor moieties were attached to the phenyl linker. The degree of dipole orientation of the three TADF emitters was in the order of para- (0.84)>meta- (0.76)>ortho- (0.72) substitution, demonstrating that extended molecular geometry by para-substitution is a key parameter to induce the dipole orientation of the TADF emitters.