Synthesis and Properties of 2,3,6,7-Tetraarylbenzo[1,2-b:4,5-b']difurans as Hole-Transporting Material

摘要

Arylamine derivatives have been used as the hole-transporting material (HTM) in multilayer organic light-emitting diodes (OLEDs) for 20 years. α-NPD, which is a diarylamino-substituted biphe-nyl, is the current standard, giving us the impression that the arylamino group is indispensable for high-performance HTMs. Indeed, there have been scarcely any attempts to find new HTMs that do not contain any arylamino groups. We describe herein a new method for the synthesis of a series of 2,3,6,7-tetraarylbenzo-[l,2-b:4,5-b′]difurans (BDFs), and report that they function as HTMs in layered OLEDs. The BDF skeleton by itself serves as an excellent HTM, and improvement of the physical properties can be achieved by suitable functionalization.