Tissa Sajoto

Saturated deep blue organic electrophosphorescence using a fluorine-free emitter

We demonstrate saturated, deep blue organic electrophosphorescence using the facial- and meridianal- isomers of the fluorine-free emitter tris(phenyl-methyl-benzimidazolyl)iridium(III)(f-Ir(pmb)3 and m-Ir(pmb)3, respectively) doped into the wide energy gap host, p-bis(triphenylsilyly)benzene (UGH2). The highest energy electrophosphorescent transition occurs at a wavelength of λ=389nm for the fac- isomer and λ=395nm for the mer- isomer. The emission chromaticity is characterized by Commission Internationale de l’Eclairage coordinates of (x=0.17,y=0.06) for both isomers. Peak quantum and power efficiencies of (2.6±0.3)% and (0.5±0.1)lm∕W and (5.8±0.6)% and (1.7±0.2)lm∕W are obtained using f-Ir(pmb)3 andm-Ir(pmb)3 respectively. This work represents a departure from previously explored, fluorinated blue phosphors, and demonstrates an efficient deep blue/near ultraviolet electrophosphorescent device.

22.1: Invited Paper: Color Tuning Dopants for Electrophosphorescent Devices: Toward Efficient Blue Phosphorescence from Metal Complexes

In this paper, we describe different strategies for achieving efficient blue electrophosphorescence. The first approach involves the use of ancillary ligand tuning of emission. The emissive unit is an organometallic Ir fragment, whose triplet energy is tuned by the choice of ancillary ligand. This approach is useful for making blue emitters, but luminance efficiency drops when the energy is shifted to saturated blue. The second approach described here is to shift the cyclometallated ligand from phenyl-pyridine to either a phenyl-pyrrazole or phenyl-imidazole. Both complexes emit strongly in the near UV, however, only the imidazole complex (carbene ligand) emits strongly at room temperature.

Color Tuning Dopants for Electrophosphorescent Devices: Efficient Blue Phosphorescence Pyrrazole and Carbene Complexes

In this paper, we describe several new Ir complexes for achieving efficient blue electrophosphorescence. The approach described here for achieving blue phosphorescence is to shift the cyclometallated ligand from phenyl-pyridine to either a phenyl pyrrazole or phenyl-imidazole. Both complexes emit strongly in the near UV, however, only the imidazole complex (carbene ligand) emits strongly at room temperature.