Kittiya Wongkhan

Tuning Color of Charged Iridium (III) Complexes with a Spiro N,N'-Bidentate Ligand

Organic light emitting diodes (OLEDs), charged iridium(III) complexes, spiro ligand Abstract. We report the synthesis, characterization and photophysical properties of a cationic cyclometalated Ir(III) complexes of general formula [Ir(ppy)2(spbpy)]+Cl, [Ir(diFppy)2(spbpy)]+Cl and [Ir(thiopy)2(spbpy)]+Cl where ppy, spbpy, diFppy and thiopy are 2-phenylpyridine, 4,5-diaza-9,9′-spirobifluorene, 2-(2′,4′-difluorophenyl)-pyridine and 2-(thiophen-2′-yl)-pyridine, respectively. The complexes exhibit strong absorption bands in the UV region in solution spectra, due to spin-allowed ligand-centred (LC) and weaker absorption bands at longer wavelengths from metal-to-ligand charge transfer (MLCT). The photoluminescence spectra of all the complexes were characterised by a combination of 3MLCT and 3π→π* states. The emission color of a cationic cyclometalated Ir(III) complexes in solution have successfully tuned from green to orange (501-582 nm).

A Novel Charged Iridium (III) Complex for Amine Sensor Application

A new phosphorescent iridium metal with cyclometalated and dimethyl carboxylate bipyridine ligands complex 1 was synthesized and characterized. The ester functional were designed and connected as amine recognition group. The UVVis absorption and luminescence properties of complex 1 were investigated with amine. The result show that complex 1 exhibited high selectivity and efficient signaling behavior n-butylamine in acid catalyst.

Suzuki-Miyaura Reaction; Novel Synthesis of C-N and N-N Ligands for Organic Light-Emitting Devices

The Pd(II)-catalyzed cross-coupling Suzuki-Miyaura reaction of aryl boronic acid and aryl halide was investigated. We found that 1% PdCl2(PPh3)2,10% PPh3 and 1 M Na2CO3 (aq.) in refluxing 1,4-dioxane for 4 hours is the optimize condition. The desired products e.g. 2-phenyl pyridine and bipyridine derivatives were obtained in moderate to excellent yields.

A Varied Alkyl Chains of Ruthenium(II) Complexes for Dye Sensitized Solar Cells (DSSCs)

Ruthenium(II) complexes were synthesized and characterized for dye-sensitized solar cells (DSSCs) with varied alkyl chains specifically methyl (PC01), hexyl (PC02) and octyl (PC03). The photophysical property was studied by UV-Visible absorption. The results showed that the main absorption peaks were asigned to the metal to ligand charge transfer (MLCT) transition (350-600 nm). The incident photon to current conversion efficiency (IPCE) covered the entire visible spectrum reaching to 18-20% at 520 nm. The DSSC performances were investigated with liquid iodide/tri-iodide electrolyte under standard AM 1.5. PC01-PC03 showed that the power conversion efficiency (h) were obtained at 3.08%, 3.18% and 3.14%, respectively, compared with N719 (7.80%). Interestingly, PC02 and PC03 showed the long term stability with %hloss better than the standard up to 1000 h.

Charged Iridium(III) Complexes with Varied Side Chain Length in Organic Light Emitting Diodes

The four varied side chains of charged iridium(III) complexes were synthesized and characterized for organic light emitting diodes. The core materials were designed with 9,9-bis(4-methoxyphenyl)-4,5-diazafluorene as the bulky N^N ligand which prevent the π-π stacking interaction in the solid state. Their photophysical and electrochemical properties were investigated. OLEDs were fabricated with the structure ITO/PEDOT:PSS/ PVK:complex (10:7 by weight)/ TPBi/LiF/Al. The similar colors were obtained with varied OLEDs performances. We concluded that the long alkyl chains affected to the excellent film-forming property of emitting layer. Therefore, the device based on the n-octyl chain namely [(9,9-bis(4-octyloxyphenyl)-9H-cyclopentadipyridine-N-N′)-bis-(2-phenylpyridine-C2′,N)-iridium(III)] haxafluorophosphate (C8) showed the maximum current efficiency and brightness of 11.37 cd/A and 3,926 cd/m2, respectively.

Photoresponsive Nano-Coumarin with Indole Auxin Hormone

In this work, we designed and synthesized two photoresponsive materials with 3-indoleacetic acid (IAA) plant hormone which can be monitored from the photoreposive properties of coumarin. The varied position of the long alkoxy side chain (-OC16H33) was purposely introduced to adhesive on the plant leaves. Two coumarin-caged nanomaterials showed average particle diameter about 400 nm and gave the maximum emission wavelength at 425 and 450 nm. The formulated nanoemulsion showed good wettability (θ=48o) with Cassia fistula leave surface. Interestingly, CM2 gave the short photoresponse of photolysis within one day.

Synthesis and characterization of poly(fluorene) with charged iridium(III) complex

A phosphorescent iridium in the poly (fluorene) was synthesized and characterized by UV-Vis absorption and luminescence properties. The highly thermal stable was investigated by TGA. The result shows that the polymer could be a good candidate in PLED device.

Two Ruthenium Complexes with Phenanthroline Ligand for Dye-Sensitized Solar Cells

We report the synthetic route of two ruthenium dye-sensitizers; namely, Ru(4,4-dicarboxylic-2,2-bipyridine)(1,10-phenanthroline)(NCS)2 (6) and Ru(4,4-dicarboxylic-2,2-bipyridine)(1,10-phenanthroline-5-carboxylic acid)(NCS)2 (7), which both complexes were characterized by 1H NMR, 13C NMR and UV-Vis spectroscopic techniques.

Design and Synthesis of Ruthenium (II) Complexes and their Applications in Dye Sensitized Solar Cells (DSSCs)

Three thiocyanate-free ruthenium (II) sensitizers, [RuII(dcppy)(L1-L3)](PF6)] where dcppy = 4, 4-dicarboxylic acid-2, 2-bipyridine, L1 = 2-(2,4-difluorophenyl)-5-(trifluoromethyl) pyridine, L2 = 2-(2,4-difluorophenyl) pyridine and L3 = 2-phenyl-5-(trifluoromethyl) pyridine were synthesized and applied for dye-sensitized solar cells (DSSCs). The structures of ruthenium complexes were characterized by 1H, 13C NMR and IR spectra. The absorption was studied by UV-Vis spectroscopy and the electrochemical property was determined by cyclic voltammetry. The surface morphology of ruthenium complexes on mica was examined by atomic force microscopy. The performance of this complexes as photosensitizer in TiO2 based dye sensitized solar cells is studied under standard AM 1.5 sunlight and by using an electrolyte.