Highly Efficient Blue‐Emitting Iridium(III) Carbene Complexes and Phosphorescent OLEDs

Abstract

Bright & blue: A strategy for reducing metal‐chelate internal strain enables the preparation of blue emitting iridium(III) carbene complexes (see picture; Ir red, N light blue, F green). The phosphorescent OLED fabricated from one of these complexes shows remarkable CIE coordinates of (0.16, 0.13) and peak efficiencies of 6.0 % photons per electron, 6.3 cd A−1, and 4.0 lm W−1.

An Enantiopure Cyclometallated Iridium Complex Displaying Long‐Lived Phosphorescence both in Solution and in the Solid State

“…These metric data are similar to corresponding values for other reported carbenic cycloiridiated complexes. [20][21][22][23][24][25][26][27][28][29] The [4]helicenic part displays a helicity (dihedral angle between terminal rings) of 29.07°in the solid state, but it is not configurationally stable in solution (only one pair of enantiomers, vide infra). It may be noted that upon coordination to iridium, the π-system has been further elongated to seven fused aromatic rings, including the carbenic ring.…”

“…Since NHCs are strong-field ligands, NHC-based cycloiridiated complexes may attract interest as deep blue phosphors, a particularly challenging target in the OLED area. [20][21][22][23][24][25][26][27] Moreover, if a single enantiomer of such chiral com-plexes can be isolated, then the possibility of exploiting chiroptical properties such as circular polarization is opened up. In this context, we have recently shown for the first time that helicene-based NHCs can be synthesized, giving access to enantiopure iridium complexes that display strong chiroptical properties, especially intense electronic circular dichroism (ECD) [28] and longlived circularly polarized luminescence (CPL).…”

Luminescent Platinum(IV) Complexes Bearing Cyclometalated 1,2,3‐Triazolylidene and Bi‐ or Terdentate 2,6‐Diarylpyridine Ligands

“…[42,43] We anticipated that the donor properties of the triazolylidene moiety would benefit the emission efficiencies of cyclometalatedP t IV complexes by increasing the energy of deactivating excited states of LMCT character to ag reater extent than in the case of 2-arylpyridines. Cyclometalating aryl-NHC ligands have previously been employed for the synthesis of luminescentc omplexes of Ir III , [44][45][46][47][48][49][50][51][52] Pt II , [53][54][55][56] and Au III [57] with enhanced emission properties, often as non-chromophorics upporting ligands. However, most of them are normal 2-imidazolylidene-typea ryl-NHCs, whereas mesoionic aryl-NHCs have only been employed to prepare a limited number of luminescent Pt II complexeso ft he type [Pt(C^C*)(O^O)] (O^O = b-diketonate).…”

Toward High‐Performance Vacuum‐Deposited OLEDs: Sublimable Cationic Iridium(III) Complexes with Yellow and Orange Electroluminescence

“…[3] In fluorescent OLEDs, radiative decay of the 75 %t riplet excitons is spin-forbidden and only the 25 %s inglet excitonsl uminesce,w hereas phosphorescent OLEDs can facilitate the singlet-triplet mixingb ye ffective spin-orbit coupling, harvest both singleta nd triplet excitons, thus achieve near-unity internalq uantum efficiency (IQE). [6][7][8][9][10][11][12][13] Neutral complexes of ruthenium(II), [14][15][16] osmium(II), [17][18][19][20] iridium(III), [21][22][23][24][25][26][27] and platinum(II) [4,[28][29][30][31][32][33][34] have been rapidlyd eveloped and widely employed as phosphorescent dopants for polychromic OLEDs. [6][7][8][9][10][11][12][13] Neutral complexes of ruthenium(II), [14][15][16] osmium(II), [17][18][19][20] iridium(III), …”