title: Green Phosphorescence and Electroluminescence of Sulfur Pentafluoride-Functionalized Cationic Iridium(III) Complexes.
abstract: We report on four cationic iridium(III) complexes [Ir(C^N)2(dtBubpy)](PF6) that have sulfur pentafluoride-modified 1-phenylpyrazole and 2-phenylpyridine cyclometalating (C^N) ligands (dtBubpy = 4,4'-di-tert-butyl-2,2'-bipyridyl). Three of the complexes were characterized by single-crystal X-ray structure analysis. In cyclic voltammetry, the complexes undergo reversible oxidation of iridium(III) and irreversible reduction of the SF5 group. They emit bright green phosphorescence in acetonitrile solution and in thin films at room temperature, with emission maxima in the range of 482-519 nm and photoluminescence quantum yields of up to 79%. The electron-withdrawing sulfur pentafluoride group on the cyclometalating ligands increases the oxidation potential and the redox gap and blue-shifts the phosphorescence of the iridium complexes more so than the commonly employed fluoro and trifluoromethyl groups. The irreversible reduction of the SF5 group may be a problem in organic electronics; for example, the complexes do not exhibit electroluminescence in light-emitting electrochemical cells (LEECs). Nevertheless, the complexes exhibit green to yellow-green electroluminescence in doped multilayer organic light-emitting diodes (OLEDs) with emission maxima ranging from 501 nm to 520 nm and with an external quantum efficiency (EQE) of up to 1.7% in solution-processed devices.
authors.affiliation: †Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife, KY16 9ST, United Kingdom.
authors.forename: Nail M
authors.initials: NM
authors.lastname: Shavaleev
authors.affiliation: ‡Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife, KY16 9SS, United Kingdom.
authors.forename: Guohua
authors.initials: G
authors.lastname: Xie
authors.affiliation: ‡Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife, KY16 9SS, United Kingdom.
authors.forename: Shinto
authors.initials: S
authors.lastname: Varghese
authors.affiliation: §EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife, KY16 9ST, United Kingdom.
authors.forename: David B
authors.initials: DB
authors.lastname: Cordes
authors.affiliation: §EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife, KY16 9ST, United Kingdom.
authors.forename: Alexandra M Z
authors.initials: AM
authors.lastname: Slawin
authors.affiliation: ∥Instituto de Ciencia Molecular, Universidad de Valencia, C/J. Beltran 2, 46980 Paterna, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Momblona
authors.affiliation: ∥Instituto de Ciencia Molecular, Universidad de Valencia, C/J. Beltran 2, 46980 Paterna, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Ortí
authors.affiliation: ∥Instituto de Ciencia Molecular, Universidad de Valencia, C/J. Beltran 2, 46980 Paterna, Spain.
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Bolink
authors.affiliation: ‡Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife, KY16 9SS, United Kingdom.
authors.forename: Ifor D W
authors.initials: ID
authors.lastname: Samuel
authors.affiliation: †Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife, KY16 9ST, United Kingdom.
authors.forename: Eli
authors.initials: E
authors.lastname: Zysman-Colman
mesh_terms: D060326:Chemistry Techniques, Synthetic; D018360:Crystallography, X-Ray; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004867:Equipment Design; D005459:Fluorides / Q000737:chemistry; D007495:Iridium / Q000737:chemistry*; D008024:Ligands; D008163:Luminescent Measurements; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D013457:Sulfur Compounds / Q000737:chemistry
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D013457:Sulfur Compounds; C115613:sulfur pentafluoride cation; D007495:Iridium; D005459:Fluorides