Selective F or Br Functionalization of Dibenzofuran for Application as Host Materials of Phosphorescent Organic Light‐Emitting Diodes

Abstract Four dibenzofuran‐type host materials substituted with a carbazolylcarbazole moiety were synthesized to investigate the effect of substitution position on the material parameters and device performances of host materials. The carbazolylcarbazole moiety was substituted at the 1‐, 2‐, 3‐, and 4‐positions of dibenzofuran by F or Br for a comprehensive study of the positional effect of dibenzofuran‐derived host materials. Systematic synthesis and comparison of the four host materials revealed that 1‐, 2‐, and 4‐position modification was better than 3‐position modification for high triplet energy and high external quantum efficiency.