• Korea-Australia Rheology Journal
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• 제13권4호
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• pp.197-203
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• 2001

We reported on the eletrorheological (ER) properties of several semiconducting polymers including poly (p-phenylene) (PPP), poly (acene quinone) radicals (PAQRs), microencapsulated polyaniline (MPANI) and polyaniline (PANI) those we synthesized. The yield stress dependence on electric field strength for the ER fluids using these semiconducting polymers was mainly examined. The yield stress, which is an important design parameter for ER fluids, was observed to satisfy a universal scaling function, allowing that yield stress data for all the ER fluids examined in this study collapse onto a single curve for a broad range of electric field strengths. The proposed scaling function incorporates both the polarization and conductivity models.

• 한국광과학회:학술대회논문집
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• 한국광과학회 1996년도 학술대회지
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• pp.40-40
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• 1996

• 한국재료학회:학술대회논문집
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• 한국재료학회 1998년도 IUMRS-ICEM ABSTRACT BOOK
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• pp.38.1-38
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• 1998

• 한국진공학회:학술대회논문집
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• 한국진공학회 2008년도 제34회 동계학술대회 초록집
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• pp.251-251
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• 2008

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.3.1-3.1
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• 2011

Nanoengineered materials with advanced architectures are critical building blocks to modulate conventional material properties or amplify interface behavior for enhanced device performance. While several techniques exist for creating one dimensional heterostructures, electrospinning has emerged as a versatile, scalable, and cost-effective method to synthesize ultra-long nanofibers with controlled diameter (a few nanometres to several micrometres) and composition. In addition, different morphologies (e.g., nano-webs, beaded or smooth cylindrical fibers, and nanoribbons) and structures (e.g., core-.shell, hollow, branched, helical and porous structures) can be readily obtained by controlling different processing parameters. Although various nanofibers including polymers, carbon, ceramics and metals have been synthesized using direct electrospinning or through post-spinning processes, limited works were reported on the compound semiconducting nanofibers because of incompatibility of precursors. In this work, we combined electrospinning and galvanic displacement reaction to demonstrate cost-effective high throughput fabrication of ultra-long hollow semiconducting chalcogen and chalcogenide nanofibers. This procedure exploits electrospinning to fabricate ultra-long sacrificial nanofibers with controlled dimensions, morphology, and crystal structures, providing a large material database to tune electrode potentials, thereby imparting control over the composition and shape of the nanostructures that evolved during galvanic displacement reaction.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.318-318
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• 2010

We present the effect of interlayers of polymer tandem solar cells on their photovoltaic performance. P-type and n-type interlayers are essential for the series-connection of the subcells and enable to form the tandem cell architecture by the solution processing. In this study, we use PEDOT:PSS, nanocrystalline $TiO_2$, and blends of semiconducting polymers and fullerene derivatives as a hole transporting layer, electron transporting layer, and photoactive layers, respectively. We show that photovoltaic performances of polymer tandem solar cells depending on various PEDOT:PSS layers with the different electric conductivity and the various $TiO_2$ layer thickness.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.112-112
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• 2006

Detailed surface characteristics of polymer films have been investigated by atomistic molecular dynamics simulations and NEXAFS spectroscopy experiments. The geometric confinement of the surfaces and the necessity to minimize the surface energy lead to the significant molecular organization and orientation in polymer surfaces, with their properties strongly depending upon the atomistic monomer structures. As compared with polymers, oligomeric electronic materials are much more readily aligned by employing various surface anchoring forces, rendering them highly attractive as polarized-light emitting materials and active semiconducting materials in thin film transistors.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.1047-1052
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• 2003

Controlling carrier transport in light emitting polymers is extremely important for their efficient use in organic opto-electronic devices [1]. Here we show that the interactions between single wall carbon nanotubes (SWNTs) and conjugated polymers can be used to modify the overall mobility of charge carriers within nanotube-polymer nanocomposites. By using a unique, double emitting-organic light emitting diodes (DE-OLEDs) structure. we have characterized the hole transport within electroluminescent nanocomposites (nanotubes in poly (m-phenylene vinylene-co-2,5-dioctoxy-p-phenylene) or PmPV). We have shown using this idea that single devices with color tunability can be fabricated. It is seen that SWNTs in PmPV are responsible for hole trapping, leading to shifts in the emission wavelengths. Our results could lead to improved organic optical amplifiers, semiconducting devices, and displays.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2371-2376
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• 2009

Three phenoxazine-based conjugated polymers, namely, the aryl substituted phenoxazine homopolymer (P1) as well as the dimeric phenoxazine-fluorene (P2) and phenoxazine-bithiophene (P3) copolymers, were synthesized via the Ni(0) mediated Yamamoto reaction and the palladium-catalyzed Suzuki coupling reaction. The weight-averaged molecular weights ($M_w$) of P1, P2, and P3 were found to be 27,000, 22,000, and 15,000, respectively, and their polydispersity indices were 3.6, 1.8, and 2.1. All the polymers were soluble in common organic solvents such as chloroform, toluene, and so on. The UV-visible absorption maxima for P1, P2, and P3 in the film state were located at 421, 415 and 426 nm, respectively, and the ionization potentials of the polymers ranged between 4.90 and 5.12 eV. All the studied phenoxazine-based polymers exhibited amorphous behavior, as confirmed by X-ray diffraction (XRD) and atomic force microscopy (AFM) studies. Thin film transistors were fabricated using the top-contact geometry. P1 showed much better thin-film-transistor performance than P2 or P3: A thin film of P1 gave a saturation mobility of 0.81 ${\times}\;10^{-3}\;cm^2V^{-1}s^{-1}$ and an on/off ratio of about $10^2$.

• 한국광학회지
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• 제13권2호
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• pp.128-133
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• 2002

최근 주목을 받고 있는 고분자 발광다이오드의 개발에 있어서, 발광고분자의 Photoluminescence(PL)와 Electroluminescence (EL) 양자효율 측정은 소자의 성능개선 연구 등에 있어서 가장 핵심적인 요소 중 하나로 여겨진다. 이러한 이유에서 본 연구에서는 잘 알려진 발광고분자인 Poly(2-methoxy-5(-(2-ethyl-hexyloxy)- 1,4-phenylenevinylene) (MEH- PPV)를 이용하여 시편을 제작하고, 적분구 측정법을 이용하여 이의 P교라 EL 양자효율을 구하였다. 그 결과 본 연구진이 개발한 MEH-PPV의 PL 양자효율은 8$\pm$2%로 측정되었는데, 이는 세계적으로 알려져 있는 ～9%의 결과에 거의 접근함을 보였다. 한편, 이 물질을 이용하여 고분자 발광다이오드를 제작한 결과, 이의 EL양자효율은 0.02 1m/W로 측정되었다. 본 연구를 통하여 확립된 발광고분자의 양자효율 측정법은 국내의 유기발광소자 연구에 큰 기여를 하리라 기대된다.