Triphenylamine-based π-conjugated dendrimers: Convenient synthesis, easy solution processability, and good hole-transporting properties

Two, third-generation triphenylamine-based dendrimers (DT1 and DT2) were prepared through a simple convergent approach by using a combination of versatile carbon-carbon formation reactions. It is found that the π-linkages connecting the periphery into the core have a pronounced effect on the properties of the material. The introduction of CC bonds in the periphery improves the photophysical behavior and optical qualities of the films in comparison with their introduction in the core of the dendrimer. Both dendrimers exhibit high T_gs (above 240 °C) and high-lying HOMO energy levels of ∼5.2 eV. As the hole-transporting layer fabricated through a facile solution process, DT2 can endow an Alq₃ based multi-layer OLED device with a maximum brightness of 5020 cd m^-2, and a maximum current efficiency of 2.36 cd A^-1.