Rukkiat Jitchati

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).

Preparation and characterization of modified telechelic natural rubber-based pressure-sensitive adhesive

Abstract Telechelic natural rubber (TNR) was prepared by the use of potassium persulfate and propanal at 70 °C and various degradation times from 0 to 30 h. These samples were then grafted by maleic anhydride (MA) in toluene solution before modification with 3-amino-1,2,4-triazole (ATA) to produce modified TNRs (AMTNRs). Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used to identify the chemical compositions. Carboxyl and hydroxyl groups of TNRs were clearly observed, due to chain scission, oxidation, and modified chain ends. The viscosities of TNRs were dropped greatly after 5 h and then decreased slowly as a function of degradation time. ATR-FTIR spectra of AMTNRs showed amide bonds between ATA and MA groups, and then the multiple hydrogen bonding arrays were formed. The glass transition temperatures (Tg) of AMTNRs were determined by differential scanning calorimetry. The Tg of AMTNR_0 moved to a higher temperature of –55 °C after modification by ATA, confirming the formation of multiple hydrogen bonding arrays. However, the Tg of AMTNR_5 to AMTNR_30 decreased slightly due to chain scission in the degradation process. The adhesive properties of AMTNR-based pressure-sensitive adhesive were evaluated by a Lloyd adhesion tester. The tack of AMTNRs depended on wettability whereas peel and shear strengths were responded by a combination between wettability and multiple hydrogen bonding arrays.

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.

Atomic force microscopy investigation of phase morphology correlated with adhesive properties for modified telechelic natural rubber based-pressure sensitive adhesive

Abstract Atomic force microscopy (AFM) is a powerful technique to determine phase morphology and surface mechanical properties of materials. In this research natural rubber was degraded and grafted by malelic anhydride before modification with 3-amino-1,2,4-triazole to obtain modified telechelic natural rubber or modified TNR. It was then blended with cumarone-indene resin at 10, 30, and 50 phr, acting as tackifier. Phase morphology and surface topography were investigated by intermitted AFM. The results showed that tackifier enriched domains were clearly observed in modified TNR matrix after added 30 and 50 phr and the domain sizes were approximately to be the order of micrometer (5–10 µm) which it increased with increasing tackifier content. The intermolecular hydrogen bonding interaction between tackifier and modified TNR was observed by attenuated total reflectance Fourier transform infrared spectroscopy. The adhesive properties (loop tack, peel, and shear strength) were governed by the size of tackifier enriched domains, surface mean roughness and compatibility or interaction between modified TNR rubber and cumarone-indene tackifier resin.

Thiocyanate Free Ruthenium(II) Complexes for Dye Sensitized Solar Cells (DSSCs)

The four thiocyanate free ruthenium(II) complexes; [Ru(N^N)2(C^N)]PF6 were synthesized and characterized for dye sensitized solar cells (DSSCs). The results showed that the broad absorptions covered the visible region from metal to ligand charge transfer (MLCT) were obtained with the main peaks at 560, 490 and 400 nm. The materials were studied DSSC performance under standard AM 1.5. Compound PP1 showed the power conversion efficiency (PCE) at 3.10%, with a short-circuit photocurrent density (Jsc) of 7.99 mA cm-2, an open-circuit photovoltage (Voc) of 563 mV and a high fill factor (ff) of 0.690.

A Novel Charged Iridium Polymer for Polymer Light Emitting Diode

The charged iridium(III) complex polymers based on 1,10-phenanthroline in the polyfluorene backbones were synthesized by Suzuki-polycondensation. PFIr01, PFIr03, PFIr05, PFIr07 and PFIr10 were obtained by varying the content of iridium(III) unit in the polymer from 0.01, 0.03, 0.05, 0.07 and 0.10 mol%, respectively. The molecular structures of polymers were characterized by 1H NMR, 13C NMR and gel permeation chromatography. Their thermal, photophysical and electrochemical properties were investigated by thermal gravimetric analysis, UV-Visible spectroscopy, fluorescence spectroscopy and cyclic voltammetry. The polymer light-emitting diodes were fabricated with ITO/PEDOT:PSS/polymer/TPBi/BPhen/LiF/Al.

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.

A Novel Benzo[d,e]Chromene for Organic Light Emitting Diodes (OLEDs)

Organic light emitting diodes (OLEDs) have been known for the next generation of display technology. In this work, we synthesized four benzo[d,e]chromene derivatives (BS01-BS04) varying the position of fluorine atom for OLED application. The compounds were characterized by 1H and 13C NMR, FTIR and mass spectroscopy. Their photoluminescence properties were studied which showed the thermally activated delayed fluorescence (TADF) character from intramolecular charged transfer (ICT) transition. The compounds were used as a dopant for OLEDs in the structure of ITO/NPB/BS01-BS04/Bphen/LiF/Al. The BS02 device exhibited green colour with the current efficiency at 1.28 cd/A and the power efficiency at 0.47 Im/W.

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.