All-Solution-Processed Red and Orange-Red Organic Light-Emitting Diodes with High-Efficiencies: The Effect of Mixed-Host Emissive Layers and Thermal Annealing Treatment.

The instability of the organic light-emitting diodes (OLEDs) during operation can be attributed to the existence of point defects on the organic layers. In this work, the effect of mixed-host emissive layer and the thermal annealing treatment were investigated to eliminate defects and to boost the device performance. The mixed-host system includes 4,4',4''-tri (9-carbazoyl) triphenylamine (TCTA) and 2,7-bis(diphenylphosphoryl)-9, 9'-spirobi[fluorene] (SPPO13).

Pt(II) Phosphors Featuring Both Dicarbene and Functional Biazolate Chelates: Synthesis, Luminescent Properties, and Applications in Organic Light-Emitting Diodes.

Pt(II) metal complexes [Pt(C^C)(X^X)] comprising three functional dianionic azolate chelates (X^XH2: bipzH2 = 5,5'-di(trifluoromethyl)-3,3'-bipyrazole, bitzH2 = 5,5'-di(trifluoromethyl)-3,3'-bi-1,2,4-triazole, and phpzH2 = 3-(trifluoromethyl)-5-(4-(trifluoromethyl)phenyl)-1H-pyrazole), together with three different charge-neutral dicarbene chelates (i.e., C^C = 1,1'-methylene bis(3-methyl-imidazol-2-ylidene), 1,1'-methylene bis(3-isopropyl-imidazol-2-ylidene), and 1,1'-(propane-1,3-diyl) bis(3-isopropyl-imidazol-2-ylidene), were synthesized and found to show bright solid-state emission depending on the associated X^X and C^C chelates.

Ir(III)-Based Phosphors with Bipyrazolate Ancillaries; Rational Design, Photophysics, and Applications in Organic Light-Emitting Diodes.

A series of three charge-neutral Ir(III) complexes bearing both neutral chelating ligands 4,4'-di-t-butyl-2,2'-bipyridine (dtbbpy) and monoanionic cyclometalated ligands derived from 2-phenylpyridine (ppyH), together with either two monoanionic ligands (i.e., chloride and monodentate pyrazolate) or a single dianionic chelate derived from 5,5'-di(trifluoromethyl)-3,3'-bipyrazole (bipzH2) or 5,5'-(1-methylethylidene)-bis-(3-trifluoromethyl-1H-pyrazole) (mepzH2), was successfully synthesized.

Os(II) phosphors with near-infrared emission induced by ligand-to-ligand charge transfer transition.

Heating of Os3(CO)12 with 6 equiv of 2-(3-(trifluoromethyl)-1H-1,2,4-triazol-5-yl) pyridine (fptzH) in refluxing diethylene glycol monomethyl ether, followed by sequential treatment with stoichiometric Me3NO and addition of PPhMe2, afforded two isomeric mixtures of red-emitting [Os(fptz)2(PPhMe2)2] (1T and 1C), for which the notations T and C stand for the trans and cis-oriented fptz chelates, respectively. Alternatively, preparation of Os(II) complex using a 1:1 mixture of 5,5'-di(trifluoromethyl)-3,3'-di-1,2,4-triazole (dttzH2) and 2,2'-bipyridine (bpy), instead of fptzH, gave isolation of a mononuclear Os(II) complex [Os(bpy)(dttz)(CO)2] (2) in moderate yield. Replacement of CO with PPhMe2 on 2 afforded near-infrared (NIR)-emitting Os(II) complex [Os(bpy)(dttz)(PPhMe2)2] (3).

A new class of sky-blue-emitting Ir(III) phosphors assembled using fluorine-free pyridyl pyrimidine cyclometalates: application toward high-performance sky-blue- and white-emitting OLEDs.

Two pyrimidine chelates with the pyridin-2-yl group residing at either the 5- or 4-positions are synthesized. These chelates are then utilized in synthesizing of a new class of heteroleptic Ir(III) metal complexes, namely [Ir(b5ppm)2(fppz)] (1), [Ir(b5bpm)2(fppz)] (2), [Ir(b4bpm)2(fppz)] (3), and [Ir(b5bpm)(fppz)2] (4), for which the abbreviations b5ppm, b5bpm, b4bpm, and fppz represent chelates derived from 2-t-butyl-5-(pyridin-2-yl)pyrimidine, 2-t-butyl-5-(4-t-butylpyridin-2-yl)pyrimidine, 2-t-butyl-4-(4-t-butylpyridin-2-yl)pyrimidine, and 3-trifluoromethyl-5-(pyridin-2-yl) pyrazole, respectively. The single crystal X-ray structural analyses were executed on 1 to reveal their coordination arrangement around the Ir(III) metal element.