Publications by authors named "Seokwoo Kang"

We designed and synthesized new indolocarbazole-triazine derivatives, 9-di-tert-butyl-5,7-bis(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5,7-dihydroindolo[2,3-b]carbazole (2TRZ-P-ICz) and 3,9-di-tert-butyl-5,7-bis(5'-(4,6-diphenyl-1,3,5-triazin-2-yl)-[1,1':3',1″-terphenyl]-2'-yl)-5,7-dihydroindolo[2,3-b]carbazole (2TRZ-TP-ICz), as new bipolar host materials for red phosphorescent OLEDs. In the film state, 2TRZ-P-ICz and 2TRZ-TP-ICz exhibited photoluminescence maxima at 480 nm and 488 nm, respectively. The dipole moment characteristics of the new compounds under various solvent conditions were investigated using the Lippert-Mataga equation.

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We report three highly efficient multiresonance thermally activated delayed fluorescence blue-emitter host materials that include 5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracene (DOBNA) and tetraphenylsilyl groups. The host materials doped with the conventional N,N,N,N,5,9,11,15-octaphenyl-5,9,11,15-tetrahydro-5,9,11,15-tetraaza-19b,20b-diboradinaphtho[3,2,1-de:1',2',3'-jk]pentacene-7,13-diamine (ν-DABNA) blue emitter exhibit a high photoluminescence quantum yield greater than 0.82, a high horizontal orientation greater than 88%, and a short photoluminescence decay time of 0.

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Two new deep-blue emitters with bipolar properties based on an organoboron acceptor and carbazole donor were newly synthesized: 2-(9H-carbazol-9-yl)-5-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho [3,2,1-de]anthracen-7-yl)-5H-benzo[b]carbazole (TDBA-BCZ) and 5-(2,12-di-tert-butyl-5,9-dioxa-13b-boranaphtho [3,2,1-de]anthracen-7-yl)-8-phenyl-5,8-dihydroindolo[2,3-c]carbazole (TDBA-PCZ). The two emitters showed deep-blue and real-blue photoluminescence emission in their solution and film states, respectively. The doped spin-coated films were prepared using synthesized materials and showed a root-mean-square roughness of less than 0.

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Novel yellow azo pyridone dye derivatives were synthesized for use in image-sensor color filters. The synthesized compounds have a basic chemical structure composed of azo, hydroxy, amide, and nitrile groups as well as different halide groups. New materials were evaluated on the basis of their optical, thermal, and surface properties under conditions mimicking those of a commercial device fabrication process.

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Three organic blue-light-emitting tetraphenylethylene (TPE) derivatives that exhibit aggregation-induced emission (AIE) were used as additives in the preparation of inorganic perovskite-structured green-light-emitting materials for three-color white-light emission. For these organic-inorganic light-emitting materials, two-color (blue and green) light-emitting films based on the CsPbBr perovskite-structured green-light-emitting inorganic material were prepared. The three TPE derivatives were prepared by varying the number of bromide groups, and a distinct AIE effect was confirmed when the derivatives were dissolved in a water-tetrahydrofuran mixed solvent containing 90 vol% water.

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The development of rigid polyaromatic building blocks for narrowband violet fluorophores has received tremendous attention. Herein, we designed and synthesized two new triangle-shaped rigid building blocks, namely, 2,5-di--butylindolo[3,2,1-]carbazole () and 2,11-di--butylindolo[3,2,1-]carbazole-4-carbonitrile (), and tethered them with different chromophores to yield a series of violet-blue fluorophores, , , and studied their structure-function relationship. The appended chromophores and cyano unit played a vital role in controlling the optical and electrical properties of the compounds.

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Molecular size of OLED emitting materials is nano-metric size and when it is applied to the electric field it emits the light based on the energy conversion result. As new green fluorescent emitters, N,N,N',N'-Tetra--tolyl-anthracene-9,10-diamine (-Me-TAD) and -Tetra--tolyl-anthracene-9,10-diamine (-Me-TAD) were synthesized and the properties were evaluated. In solution state, photoluminescence (PL) maximum wavelength is 517 nm for -Me-TAD and 529 nm for -Me-TAD.

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OLED light emitting materials have a molecular size corresponding to the nano scale and are converted into light energy when given electrical energy. The new green fluorescent dopant material was successfully synthesized by using anthracene as a central core and introducing a methyl group and tert-butyl group at various positions as diphenylamine group. Two compounds are N,N,N,N-tetraphenylanthracene-9,10-diamine (TAD) and N,N-bis(4-(tert-butyl) phenyl)-N,N-di-o-tolylanthracene-9,10-diamine (-Tb-o-Me-TAD).

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In this study, a blue photoresist with the hybrid dye-pigment system was developed by mixing xanthene-based dye (XPDIA) and blue pigment 15:6 (1:1, 5 wt% of total mixture amount) in order to develop high-performance image sensors with high thermal and chemical stability. The colorant used in this study has the nano-sized particle of around 100 nm and the physical property is related with the photonic property in image sensor application such as the cameras of mobile phone, car black box, security, etc. The hybrid dye-pigment system showed a high transmittance of more than 90% at 450 nm, and Δ showed very low color difference of 0.

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New thermal-latent metal catalyst such as tetrakis (lauorate) titanium (LPTi) was designed and synthesized based on a lauroyl peroxide and titanium. The synthetic method is simple with one step reaction. LPTi structure was confirmed by FT-IR analysis, also nano-sized structure of LPTi confirmed using SEM-EDX.

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Two green fluorescent materials, -Tetra--tolyl-anthracene-9,10-diamine (-Me-TAD) and -bis(2,5-dimethylphenyl)-N,N'-di--tolylanthracene-9,10-diamine (DMe--Me-TAD) including anthracene and diphenylamine moiety, were synthesized by Buchwald-Hartwig amination. In solution state, PL maximum wavelength of o-Me-TAD and DMe--Me-TAD is 518 nm and 520 nm. The doped device using o-Me-TAD as green fluorescent dopant exhibited CE of 19.

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In this study, a triarylmethine derivative of DMCEBA-BTSA with the high thermal and chemical stability was newly synthesized in order to develop a high-performance image sensor. It showed a high transmittance of more than 80% at 450 nm and △ showed a very low color difference of 2.32 after thermal treatment.

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New green emitter is designed and synthesized by selecting anthracene having high photoluminescence quantum yield (PLQY) and diphenylamine side group substituted methyl and t-butyl group: ,-bis(5-(tert-butyl)-2-methylphenyl)-,-bis(2,4-dimethylphenyl)anthracene-9,10-diamine (3Me-1Bu-TPADA). Photophysical, electrochemical, and electroluminescent (EL) properties of 3Me-1Bu-TPADA were investigated. The maximum photoluminescence (PL) emission wavelengths of 3Me-1Bu-TPADA in solution and in a film were 528 nm and 531 nm, respectively.

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The aim of this study was to demonstrate the anti-inflammatory effect of PRCC-1301-derived extracellular vesicles (PRCC-1301 EVs) on intestinal inflammation and intestinal barrier function. Human intestinal epithelial cells (IECs) Caco-2 were treated with PRCC-1301 EVs and then stimulated with dextran sulfate sodium (DSS). Real-time RT-PCR revealed that PRCC-1301 EVs inhibited the expression of pro-inflammatory cytokines in Caco-2 cells.

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A new hole-transporting material, poly-2-(9-carbazol-9-yl)-5-(4-vinylphenyl)-5-benzo[]carbazole (PBCZCZ), was developed for perovskite light-emitting diodes (PeLEDs). This polymer, which is based on the benzocarbazole moiety, has good solubility in common solvents and enabled the fabrication of highly efficient multilayer perovskite devices. It has excellent film morphology and a high hole mobility of 3.

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New triazene based metal complexes such as Cu[1-(phenyldiazenyl)piperidine]2Br₂ (BTACHCuBr₂), Cu[1-(phenyldiazenyl)piperidine]2Cl₂ (BTACH-CuCl₂), Ni[1-(phenyldiazenyl)piperidine]2Cl₂ (BTACH-NiCl₂ · 6H₂O), Cu[2,2,6,6-tetramethyl-1-(phenyldiazenyl)piperidine]2Cl₂ (BTACM-SnCl₂), Ti[2,2,6,6-tetramethyl-1-(phenyldiazenyl)piperidine]2Cl₂ (BTACM-TiCl₂) were synthesized. All of the five compounds did not absorb in the visible light wavelength region and it does not have the color change disadvantage when using as an additive in polymerization. All materials also had thermal stability up to 245 °C.

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Background: Genomic data have become major resources to understand complex mechanisms at fine-scale temporal and spatial resolution in functional and evolutionary genetic studies, including human diseases, such as cancers. Recently, a large number of whole genomes of evolving populations of yeast (Saccharomyces cerevisiae W303 strain) were sequenced in a time-dependent manner to identify temporal evolutionary patterns. For this type of study, a chromosome-level sequence assembly of the strain or population at time zero is required to compare with the genomes derived later.

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Pyrene, imidazole and dibenzofuran were used to synthesize new blue emitters of 1-(4-(dibenzo[b,d]furan-4-yl)phenyl)-2-(pyren-1-yl)-1H-phenanthro[9,10-d]imidazole (BFP-PI) and 1-(4-(dibenzo[b,d]furan-4-yl)phenyl)-4,5-diphenyl-2-(pyren-1-yl)-1H-imidazole (BFP-DPI). In the film state, BFP-PI and BFP-DPI show photoluminescence (PL) maximum values of 462 nm and 459 nm. The relative PL quantum efficiency (PLQY) of BFP-PI and BFP-DPI is 89.

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We have synthesized green fluorescent emitters of ,,,-tetraphenylanthracene-9,10-diamine (TAD) and ,,,-tetra-o-tolylanthracene-9,10-diamine (Me-TAD) including anthracene and diphenylamine moiety and evaluated properties of compounds. The methyl groups were introduced to the diphenylamine to prevent molecular aggregation of the dopant and reduce self-quenching through steric hindrance of molecular structure. In solution state, photoluminescence (PL) maximum wavelength is 508 nm for TAD and 519 nm for oMe-TAD.

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White OLED (WOLED) devices were fabricated using blue emitting materials, TP-AA-TP, TP-AA-TPB, and TPB-AA-TPB, and yellow emitting material polyphenylenevinylene derivative (PDY 132). Three devices were fabricated with the following structure: ITO/PEDOT:PSS (50 nm)/PDY-132 (40 nm)/NPB (10 nm)/Blue EML (30 nm)/Alq₃ (20 nm)/LiF (1 nm)/Al (200 nm). PDY-132 was used by spin coating, and then three blue fluorescent materials were used by vapor deposition to form a white light emitting device.

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In this study, four emitters of blue light are synthesized by selecting pyrene with its high photoluminescence quantum yield (PLQY) as the core group and variants of the electron-donating diphenylamine (DPA) as side groups. The four compounds have different numbers, sizes, and substitution positions of alkyl groups on the DPA. Each of the four compounds when doped in OLED devices shows a high current efficiency (CE) of over 7 cd A and a high external quantum efficiency (EQE) of over 7.

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A new deep-blue chromophore containing a three-dimensionally (3D) shaped CS core composed of fused chrysene and spirofluorene units is synthesized. A pair of m-terphenyl (TP) units is also substituted onto the CS core at two different sets of positions to form two additional compounds: CS-TPTP and TP-CS-TP. The TP-CS-TP compound showed the highest efficiency with an external quantum efficiency (EQE) of 3.

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New blue emitting materials based on dual core concept, TP-AF-TP and TP-HAF-TP were synthesized through boronylation and Suzuki coupling reactions. In the thin film state, TP-AF-TP and TP- HAF-TP exhibited maximum PL values at 445 and 440 nm, respectively. A non-doped OLED device based on TP-AF-TP and TP-HAF-TP showed current efficiency of 3.

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New three emitting compounds, AK-1, AK-2 and AK-3 including diazocine moiety were synthesized through Suzuki-coupling reaction. Physical properties such as optical, electroluminescent properties were investigated. UV-visible spectrum of AK-1, AK-2 and AK-3 in film state showed maximum 392, 393 and 401 nm.

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Minimizing ink droplet and self-dispersed pigment mixture are becoming hot issues for high resolution of inkjet printing. New synergist including sulfonic acid group of PY-74 was suggested and synthesized. Pigment itself did not show water solubility but new synergist, SY-11 exhibited good solubility in water and organic solvents such as DMSO and DMF.

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