Edward A. Plummer

Blue emitting iridium complexes : synthesis, photophysics and phosphorescent devices

Homoleptic Ir(Fnppy)3 and heteroleptic (Fnppy)2Ir(acac) complexes (n = 3: F3ppy = 2-(3′,4′,6′-trifluorophenyl)pyridine; n = 4: F4ppy = 2-(3′,4′,5′,6′-tetrafluorophenyl)pyridine; acac = acetylacetonate) have been synthesized and their spectroscopic properties investigated. The homoleptic complexes exist as two stereoisomers, facial (fac) and meridional (mer), that have been isolated and fully characterized. Their electrochemical and photophysical properties have been studied both in solution and in the solid state and electroluminescent devices have been fabricated. The emissive layers in devices have been obtained mixing the iridium complexes with a PVK [poly(9-vinylcarbazole)] host matrix, in the presence of the electron carrier Bu-PBD [2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole]. The application of a voltage (5.0–6.5 V) between the electrodes of devices leads to electro-generated blue luminescence which has similar energy to the solution emissions. Interestingly, the stability of the devices made with the homoleptic fluorinated iridium complexes strongly depends on the stereochemistry of these phosphors and high (up to 5.5%) external quantum efficiencies for the fac complexes are measured.

Mono- and di-nuclear iridium(III) complexes. Synthesis and photophysics

This paper reports the synthesis and photophysical characterization of heteroleptic mono- and di-nuclear iridium(III) complexes. The complexes contain two ortho-metalating ligands, 2-phenylpyridine, with a bipyridine derivative as the third chelating unit. In the case of the dinuclear complexes the two iridium moieties are connected by a conjugated bridging ligand containing three or four phenyl units. All the complexes emit at room temperature and steady state and time resolved spectroscopy demonstrates that the lowest excited state is a metal-to-ligand charge transfer involving the bipyridine ligand.

Tuning iridium(iii) phenylpyridine complexes in the ?almost blue? regionElectronic Supplementary Information (ESI) available: experimental procedures, characterisation of the complexes and UV?visible absorption spectra. See http://www.rsc.org/suppdata/cc/b4/b406851c/

We report on the synthesis and photophysical properties of blue emitting iridium(iii) complexes. The use of a negatively charged ligand, such as a triazolyl pyridine, allows a facile preparation, maintaining the high energy emission (blue region) of heteroleptic complexes. We discuss the role played by electron withdrawing substituents of a different nature and also how the substitution position of the same group influences the spectroscopical behaviour.