The new deep-blue iridium(III) complexes, (TF)2Ir(pic), (TF)2Ir(fptz), (HF)2Ir(pic), and (HF)2Ir(fptz), consisting of 2',4″-difluororphenyl-3-methylpyridine with trifluoromethyl carbonyl or heptafluoropropyl carbonyl at the 3' position as the main ligand and a picolinate or a trifluoromethylated-triazole as the ancillary ligand, were synthesized and characterized for applications in organic light-emitting diodes (OLEDs). Density function theory (DFT) calculations showed that these iridium complexes had a wide band gap, owing to the introduction of the strong electron withdrawing perfluoro carbonyl group. Time-dependent DFT (TD-DFT) calculations suggested that their lowest triplet excited state was dominated by a HOMO → LUMO transition and that the contribution of the metal-to-ligand charge transfer (MLCT) was higher than 34% for all four complexes, indicating that strong spin-orbit coupling exists in the complexes. The 10 wt % (TF)2Ir(pic) doped 9-(3-(9H-carbazole-9-yl)phenyl)-3-(dibromophenylphosphoryl)-9H-carbazole (mCPPO1) film exhibited the highest photoluminescence quantum yield of 74 ± 3% among the films based on the four complexes. Phosphorescent OLEDs based on (TF)2Ir(pic) and (TF)2Ir(fptz) exhibited maximum external quantum efficiencies of 17.1% and 8.4% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.141, 0.158) and (0.147, 0.116), respectively. These CIE coordinates represent some of the deepest blue emissions ever achieved from phosphorescent OLEDs with considerably high EQEs.

Poly(5′,5′′-bithiophene-alt-2,6-[(1,5-didecyloxy)naphthalene]) (PBDN) was synthesized from 2,6-dibromo-l,5-didecyloxynaphthalene and 1,1′-[2,2′-bithiophene]-5,5′-diylbis[1,1,1-trimethylstannane] and was used as the active layer in organic thin-film transistors (OTFTs) and organic photovoltaic cells (OPVs). The obtained PBDN was soluble in organic solvents such as chloroform, chlorobenzene, and toluene and had a weight-averaged molecular weight of 9100, with a polydispersity index of 1.31. The photoluminescence (PL) maximum of the polymer was found at 500 and 530 nm in solution and at 567 nm in the film state, respectively. The highest occupied molecular orbital (HOMO) level of PBDN was low (−5.38 eV, ultraviolet photoemission spectroscopy and cyclic voltammetry), and the solution-processed thin-film transistors (TFTs) prepared using this polymer only showed a minimal change in their performance (<15%) after air exposure for three months, thereby retaining a field-effect-transistor (FET) mobility of 0.02 cm2/(V s). This excellent air stability is superior to those of other solution-processed polymer-based OTFTs. Analysis of the thin-film structure by in situ grazing-incidence X-ray diffraction, near-edge X-ray absorption fine structure spectroscopy, and atomic force microscopy showed that not only the low HOMO level of PBDN but also the presence of close-packed frustrated structures in the polymer film were responsible for the superior stability of the devices. Photovoltaic performances of PBDN were also presented with a high open circuit voltage of 0.83 V and power conversion efficiency of 1.3% when blended with [6,6]-phenyl-C61-butyric acid methyl ester.

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A series of three thiophene–naphthalene‐based asymmetric oligomers—5‐decyl‐2,2′:5′,2′′:5′′,2′′′‐quaterthiophene (DtT), 5‐decyl‐5′′‐(naphthalen‐2‐yl)‐2,2′:5′,2′′‐terthiophene (D3TN), and 5‐(4‐decylphenyl)‐5′‐(naphthalen‐2‐yl)‐2,2′‐bithiophene (DP2TN)—was synthesized by Suzuki cross‐coupling reactions. The long alkyl side chains improved both the solubility of the oligomers in solvents and their tendency to self‐assemble. UV/Vis absorption measurements suggested that DtT, D3TN, and DP2TN form H‐type aggregates with a face‐to‐face packing structure. In addition, the three oligomers were found to adopt vertically aligned crystalline structures in films deposited on substrates, as revealed by grazing‐incidence wide‐angle X‐ray scattering. These oligomers were used as the active layers of p‐type organic field‐effect transistors, and the resulting devices showed field‐effect mobilities of 3.3×10−3 cm2 V−1 s−1 for DtT, 1.6×10−2 cm2 V−1 s−1 for D3TN, and 3.7×10−2 cm2 V−1 s−1 for DP2TN. The differences in transistor performances were attributed to the degree of π overlap and the morphological differences determined by the molecular structures.

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We report the synthesis and device characterization of a novel iridium complex using a phenylpyridine derivative containing an imide functional group as a bis-cyclometallized ligand ((impy) 2 Ir(acac)) for orange organic light-emitting diodes (OLEDs). The photoluminescence of the dopant emits orange light with the main peak of 560 nm and a shoulder of 595 nm. The OLEDs made with the synthesized dopant also produce intense orange electroluminescence at 568-572 nm wavelengths depending on the device geometry. Very high peak external quantum efficiencies of 13.8-14.4%, peak power efficiencies of 29.2-32.7 lm/W, and low operation voltages of 5.3-5.4 V at 1000 cd/m 2 have been demonstrated for the orange OLEDs.Scheme 1 Synthesis of iridium(III) bis(2-isopropyl-5-(pyridin-2-yl)isoindoline-1,3-dione-N,C 2 0 )(acetyl acetonate).

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