Highly efficient blue phosphorescent and electroluminescent Ir(iii) compoundsElectronic supplementary information (ESI) available: 1H NMR, 13C NMR and 19F NMR spectra of 1–3. Absorption and emission spectra of 1–3. Molecular calculation details. Cyclic voltammetry of 1–3. See DOI: 10.1039/c2tc00270a

Three new Ir(iii) compounds with deep-blue phosphorescence have been synthesized. These molecules have the general formula of Ir(C∧N)2(L∧X), where C∧N = 2′,6′-difluoro-2,3′-bipyridine (dfpypy) and L∧X = ancillary ligand such as 2-picolinate, pic (1), acetylacetonate, acac (2), or dipivaloylmethanoate, dpm (3). The ancillary ligands have been found to significantly destabilize both HOMO and LUMO levels of the Ir(iii) complexes, compared to Ir(dfpypy)3, without significantly changing the phosphorescence energy. Compounds 1–3emit bright blue phosphorescence with λmax= 440–460 nm and quantum efficiencies of 0.60–0.95 in solution and the solid state. Double-layer electroluminescent devices using compounds 1–3as the dopant, CDBP (4,4′-bis(9-carbazolyl)-2,2′-dimethylbiphenyl) as the host/hole transporting layer, and TPBi (1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene) as the electron transport layer have been fabricated. These EL devices show pure blue colour with high efficiency. The EL device of compound 3at the doping level of 20 wt% shows the best performance with EQE of 10–15% at the brightness of 10–1000 cd m−2and the maximum current efficiency of 22 cd A−1.