With
the great success of organic light-emitting diodes (OLEDs) based on
thermal evaporation techniques, the development of printable materials
for inkjet-printing high-performance OLEDs is particularly attractive
yet challenging. In this paper, a set of printable Ir(III)-complexed
polydendrimers, poly[bis[2-(2,4-difluorophenyl)-4-(4-((2-ethylhexyl)oxy)phenyl)pyridine][1-ethyl-5-phenyl-3-propyl-1H-1,2,4-triazole] iridium(III)] (PIr-D1) and
poly[bis[2-(2,4-difluorophenyl)-4-(4-((2-ethylhexyl)oxy)-2,6-dimethylphenyl)pyridine][1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole] iridium(III)] (PIr-D2), were
designed and synthesized via ring-opening metathesis polymerization
(ROMP). As a comparison, the iridium precursor complexes bis[2-(2,4-difluorophenyl)-4-(4-((2-ethylhexyl)oxy)phenyl)pyridine][1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole]iridium(III) (Ir-D1) and bis[2-(2,4-difluorophenyl)-4-(4-((2-ethylhexyl)oxy)-2,6-dimethylphenyl)pyridine][1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole] iridium(III) (Ir-D2) and
the core structure bis[2-(2,4-difluorophenyl)pyridine] [1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole] iridium(III) (Ir-D0) were
also synthesized and the corresponding OLEDs were fabricated. Compared
with the dendritic iridium complexes Ir-D1 and Ir-D2, the resulting polydendrimers PIr-D2 and PIr-D2 showed enhanced film-forming properties, good thermal
stability, and attractive ink rheological characteristics with a suitable
viscosity for inkjet-printing. Promising device performance has been
achieved for the resulting polydendrimers by both spin-coating and
inkjet-printing, showing low driving voltages and relatively high
current efficiencies and brightnesses. The results suggest that the
construction of polydendritic Ir(III) complexes is an attractive design
strategy for exploring efficient printable light-emitting materials
for inkjet-printing high-performance OLEDs.
