The synthesis and characterization of a series of new cyclometalated iridium(III) complexes [Ir(ppy)(NN)][PF] in which Hppy = 2-phenylpyridine and NN is (pyridin-2-yl)benzo[d]thiazole (L1), 2-(4-(tert-butyl)pyridin-2-yl)benzo[d]thiazole (L2), 2-(6-phenylpyridin-2-yl)benzo[d]thiazole (L3), 2-(4-(tert-butyl)-6-phenylpyridin-2-yl)benzo[d]thiazole (L4), 2,6-bis(benzo[d]thiazol-2-yl)pyridine (L5), 2-(pyridin-2-yl)benzo[d]oxazole (L6), or 2,2'-dibenzo[d]thiazole (L7) are reported. The single crystal structures of [Ir(ppy)(L1)][PF]·1.5CHCl, [Ir(ppy)(L6)][PF]·CHCl, and [Ir(ppy)(L7)][PF] have been determined. The new complexes are efficient red emitters and have been used in the active layers in light-emitting electrochemical cells (LECs). The effects of modifications of the 2-(pyridin-2-yl)benzo[d]thiazole ligand on the photoluminescence and LEC performance have been examined. Extremely stable red-emitting LECs are obtained, and when [Ir(ppy)(L1)][PF], [Ir(ppy)(L2)][PF], or [Ir(ppy)(L3)][PF] are used in the active layer, device lifetimes greater than 1000, 6000, and 4000 h, respectively, are observed.

Small quantities of Cl(-) ions result in dramatic reductions in the performance of ionic transition metal complexes in light-emitting electrochemical cells. Strong ion-pairing between aromatic protons and chloride has been established in both the solid state and solution. X-ray structural determination of 2{[Ir(ppy)2(bpy)][Cl]}·2CH2Cl2·[H3O]·Cl reveals the unusual nature of an impurity encountered in the preparation of [Ir(ppy)2(bpy)][PF6].

A series of [Ir(C^N)2(bpy)][PF6] complexes in which the cyclometallating ligands contain fluoro, sulfane or sulfone groups is reported. The conjugate acids of the C^N ligands in the complexes are 2-(4-fluorophenyl)pyridine (H1), 2-(4-methylsulfonylphenyl)pyridine (H3), 2-(4-(t)butylsulfanylphenyl)pyridine (H4), 2-(4-(t)butylsulfonylphenyl)pyridine (H5), 2-(4-(n)dodecylsulfanylphenyl)pyridine (H6), 2-(4-(n)dodecylsulfonylphenyl)pyridine (H7). The single crystal structures of H3 and H5 are described. [Ir(C^N)2(bpy)][PF6] with C^N = 1, 3, 4, 5 and 7 were prepared from the appropriate [Ir2(C^N)4Cl2] dimer and bpy; the structure of [Ir2(3)4Cl2]·2CH2Cl2 was determined. [Ir(6)2(bpy)][PF6] was prepared by nucleophilic substitution starting from [Ir(1)2(bpy)][PF6]. The [Ir(C^N)2(bpy)][PF6] complexes have been characterized by NMR, IR, absorption and emission spectroscopic and mass spectrometric methods. The single crystal structures of enantiomerically pure Δ-[Ir(1)2(bpy)][PF6] and of rac-4{[Ir(1)2(bpy)][PF6]}·Et2O·2CH2Cl2 are described, and the differences in inter-cation packing in the structures compared. [Ir(1)2(bpy)][PF6], [Ir(4)2(bpy)][PF6] and [Ir(6)2(bpy)][PF6] (fluoro and sulfane substituents) are yellow emitters (λ(em)(max) between 557 and 577 nm), and the room temperature solution emission spectra are broad. The sulfone derivatives [Ir(3)2(bpy)][PF6], [Ir(5)2(bpy)][PF6] and [Ir(7)2(bpy)][PF6] are green emitters and the emission spectra are structured (λ(em)(max) = 493 and 523 to 525 nm). High photoluminescence quantum yields (PLQYs) of 64-74% are observed for the sulfone complexes in degassed solutions. The emission lifetimes for the three complexes containing sulfone substituents are an order of magnitude longer (2.33 to 3.36 μs) than the remaining complexes (0.224 to 0.528 μs). Emission spectra of powdered solid samples have also been recorded; the broad emission bands have values of λ(em)(max) in the range 532 to 558 nm, and PLQYs for the powdered compounds are substantially lower (≤23%) than in solution. Trends in the redox potentials for the [Ir(C^N)2(bpy)][PF6] complexes are in accord with the observed emission behaviour.

ARTICLE This journal is © The Royal Society of Chemistry 2013J. Name., 2013, 00, 1-3 | 1 to a semiconductor surface; this complex also exhibits the most favourable absorption properties among the complexes studied.

An adaptable strategy to introduce different anchors to [Ru(N⁁N)2(C⁁N)]+ dyes is described; use of a phosphonic acid anchor on NiO leads to p-type DSCs with JSC = 3.38 mA cm−2 and PEC of 0.116%.