Nickel <b>-</b> Catalyzed Synthesis of Defined Cyclic Polyene Oligomers: An Architecture for Amorphous Charge Transport Materials

We introduce a structural strategy to develop amorphous hole-transporting materials for organic electronics. Utilizing a highly selective nickel-catalyzed cycloaddition oligomerization of 1,6-diyne monomers containing triphenylamine (TPA) or N,N-diphenylnaphthalen-1-amine (DPNA) moieties afforded cyclic polyene oligomers (2a and 2b) in high yields. These medium-sized oligomers are structurally defined, possessing narrow molecular weight polydispersities and adopting an unusual rigid, shrunken cyclic conformation. This feature enables dense accumulation of conductive TPA/DPNA moieties. The resulting materials exhibit excellent thermal stability and successfully maintain a desired amorphous-like morphology in the solid state. Hole-only devices constructed with these oligomers show effective electrical conductivity, achieving a high number of hole mobilities.