• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.667-670
• /
• 2007

A new series of highly bright and efficient poly(pphenylenevinylene) s (PPV)s based on polyhedral oligomeric silsesquioxanes (POSSs) was synthesized via the Gilch polymerization method. The three POSScontaining PPVs are as follows: POSS05- PPV(containing 5 mol % POSS-appended PPV units), POSS25-PPV(containing 25 mol % POSS-appended PPV units), and POSS100-PPV(containing 100 mol % POSS-appended PPV units; this is the first ${\pi}-conjugated$ polymer composed of 100 mol % POSSsappended repeating units). The POSS-containing PPVs exhibit higher glass transition temperatures $(64-77^{\circ}C)$ than that of MEH-PPV $(58^{\circ}C)$, indicating that electroluminescence (EL) devices fabricated with these polymers should have good thermal stabilities. Light-emitting diodes (LEDs) with the configuration of ITO/PEDOT:PSS/polymer/Ca/Al were fabricated using the novel POSS-containing PPVs. Surprisingly, the luminescence efficiency (0.48 cd/A at $10540\;cd/m^2$) of the binary blend consisting 5 wt % of POSS25-PPV and 95 wt % of MEH-PPV was found to be enhanced by a factor of 6.4 with a maximum brightness of $11010cd/m^2$ (at 14.3 V).

• Journal of the Korean Vacuum Society
• /
• v.22 no.4
• /
• pp.211-217
• /
• 2013

Two types of organic thin film solar cell devices with bulk hetero-junction (BHJ) structure were fabricated on plastic substrates using conjugated polymers of $PCDTBT:PC_{71}BM$ and $PTB7:PC_{71}BM$ blended as active channel layer. Time-variant characteristics of the organic thin film solar cell devices were investigated: short circuit current density ($J_{SC}$); open circuit voltage ($V_{OC}$); ; fill factor (FF); power conversion efficiency (PCE, ŋ). All the performance parameters were degraded by progress of the measurement time, while $V_{OC}$ showed the most drastic decrease with time. Possible factors to cause the time-variant alteration of performance parameters were discussed to be clarified.

• Polymer(Korea)
• /
• v.35 no.6
• /
• pp.558-564
• /
• 2011

The biocompatibility and biodegradability of poly(amino acid) make them ideal candidates for many bio-related applications. Poly(aspartic acid), PASP, is one of synthetic water-soluble polymers with proteinlike structure, and has been extensively explored for the potential industrial and biomedical applications due to its biodegradable, biocompatible and pH-responsive properties. In this work, amino acid-conjugated PASPs were prepared by aminolysis reaction onto polysuccinimide (PSI) using ${\gamma}$-aminobutylic acid(GABA) and ${\beta}$-alanine methyl ester and a subsequent hydrolysis process. Their chemical gels were prepared by crosslinking reaction with ethylene glycol diglycidyl ether (EGDE). The hydrogels were investigated for their basic swelling behavior, hydrolytic degradation and morphology. The crosslinked gels showed a responsive swelling behavior, which was dependent on pH and salt concentration in aqueous solution, and relatively fast hydrolytic degradation.

• Applied Chemistry for Engineering
• /
• v.24 no.4
• /
• pp.396-401
• /
• 2013

Alternating copolymers, poly[9-(2-octyl-dodecyl)-9H-carbazole-alt-4,7-di-thiophen-2-yl-benzo[1,2,5]thiadiazole] (PCD20TBT) and poly[9,10-bis-(2-octyl-dodecyloxy)-phenanthrene-alt-4,7-di-thiophen-2-yl-benzo[1,2,5]thiadiazole] (PN40TBT), were synthesized by the Suzuki coupling reaction. The copolymers were soluble in common organic solvents such as chloroform, chlorobenzene, 1,2-dichlorobenzene, tetrahydrofuran and toluene. The maximum absorption wavelength and the band gap of PCD20TBT were 535 nm and 1.75 eV, respectively. The maximum absorption wavelength and the band gap of PN40TBT were 560 nm and 1.97 eV, respectively. The HOMO and the LUMO energy level of PCD20TBT were -5.11 eV and -3.36 eV, respectively. As for PN40TBT, the HOMO and the LUMO energy level of PCD20TBT were -5.31 eV and -3.34 eV, respectively. The polymer solar cells (PSCs) based on the blend of copolymer and PCBM (1 : 2 by weight ratio) were fabricated. The power conversion efficiencies of PSCs based on PCD20TBT and PN40TBT were 0.52% and 0.60%, respectively. The short circuit current density ($J_{SC}$), fill factor (FF) and open circuit voltage ($V_{OC}$) of the device with PCD20TBT were $-1.97mA/cm^2$, 38.2% and 0.69 V. For PN40TBT, the $J_{SC}$, FF, and $V_{OC}$ were $-1.77mA/cm^2$, 42.9%, and 0.79 V, respectively.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.2
• /
• pp.505-512
• /
• 2014

A new donor-accepter-donor-accepter-donor (D-A-D-A-D) type 2,1,3-benzothiadiazole-thiophene-based acceptor unit 2,5-di(4-(5-bromo-4-octylthiophen-2-yl)-2,1,3-benzothiadiazol-7-yl)thiophene ($DTBTTBr_2$) was synthesized. Copolymerized with fluorene and indeno[1,2-b]fluorene electron-rich moieties, two alternating narrow band gap (NBG) copolymers PF-DTBTT and PIF-DTBTT were prepared. And two copolymers exhibit broad and strong absorption in the range of 300-700 nm with optical band gap of about 1.75 eV. The highest occupied molecular orbital (HOMO) energy levels vary between -5.43 and -5.52 eV and the lowest unoccupied molecular orbital (LUMO) energy levels range from -3.64 to -3.77 eV. Potential applications of the copolymers as electron donor material and $PC_{71}BM$ ([6,6]-phenyl-$C_{71}$ butyric acid methyl ester) as electron acceptors were investigated for photovoltaic solar cells (PSCs). Photovoltaic performances based on the blend of PF-DTBTT/$PC_{71}BM$ (w:w; 1:2) and PIF-DTBTT/$PC_{71}BM$ (w:w; 1:2) with devices configuration as ITO/PEDOT: PSS/blend/Ca/Al, show an incident photon-to-current conversion efficiency (IPCE) of 2.34% and 2.56% with the open circuit voltage ($V_{oc}$) of 0.87 V and 0.90 V, short circuit current density ($J_{sc}$) of $6.02mA/cm^2$ and $6.12mA/cm^2$ under an AM1.5 simulator ($100mA/cm^2$). The photocurrent responses exhibit the onset wavelength extending up to 720 nm. These results indicate that the resulted narrow band gap copolymers are viable electron donor materials for polymer solar cells.

• Clean Technology
• /
• v.20 no.4
• /
• pp.415-424
• /
• 2014

In this study, two kinds of polymer (PPQX-2hdPTZ (P1), POPQX-2hdPTZ (P2)) were synthesised by Suzuki coupling reaction based on phenothiazine derivative as electron-donor and quinoxaline derivative as electron-acceptor. Microwave synthesis workstation was used to shorten the polymerization time and increase the degree of polymerization. The physical, thermal stability, optical and electrochemical properties of the synthesized polymer were confirmed. The thermal stability of two polymers was outstanding as the initial decomposition temperature was $323-328^{\circ}C$. And additional substituted alkoxy chain on P2 showed higher degree of polymerization. An analysis of electrochemical properties, all polymer had similar HOMO energy level values. Device was fabricated by ITO/PEDOT:PSS/active layer/$BaF_2$/Al structure and photovoltaic properties were confirmed. Each device has a different film thickness and the resulting change in PCE was confirmed. As a result the thinner thickness of the film showed a high efficiency ($PCE_{max}:P1=1.0%$, P2 = 1.1%).

• Journal of Adhesion and Interface
• /
• v.24 no.2
• /
• pp.64-68
• /
• 2023

Organic field-effect transistors (OFETs) are attracting attention in the field of next-generation electronic devices, and they can be fabricated on a flexible substrate using an organic semiconductor as a channel layer. In particular, DPP-based semiconducting conjugated polymers are actively used because they have higher charge carrier mobility than other organic semiconductors, but they are still lower than inorganic semiconductors, so various studies are being conducted to improve the charge carrier mobility. In this study, the charge carrier mobility is improved by controlling the surface energy of the substrate by forming self-assembled monolayers (SAMs). As the surface energy of the substrate is controlled by the SAMs, the crystallinity increases, thereby improving the charge carrier mobility by 14 times from 3.57×10^-3 cm²V^-1s^-1 to 5.12×10^-2 cm²V^-1s^-1

• Applied Chemistry for Engineering
• /
• v.22 no.1
• /
• pp.15-20
• /
• 2011

Poly[2,3-dimethyl-5,8-dithiophene-2-yl-quinoxaline-alt-9,9-dihexyl-9H-fluorene] (PFTQT) and poly[2,3-dimethyl-5,8-dithiophen-2-yl-quinoxaline-alt-10-hexyl-10H-phenothiazine (PPTTQT) based on 2,3-dimethyl-5,8-dithiophen-2-yl-quinoxaline weresynthesized by Suzuki coupling reaction. All polymers were soluble in common organic solvents such as chloroform, chlorobenzene, o-dichlorobenzene, tetrahydrofuran (THF) and toluene. The maximum absorption wavelength and band gap of PFTQT were 440 nm and 2.30 eV, and PPTTQT were 445 nm and 2.23 eV, respectively. The HOMO and LUMO energy level of PFTQT were -6.05 and -3.75 eV, and PPTTQT were -5,89 and -3.66 eV, respectively. The organic photovoltaic devices based on the blend of polymer and PCBM (1 : 2 by weight ratio) were fabricated. Efficiencies of devices were 0.24% (PFTQT) and 0.16% (PPTTQT), respectively. The short circuit current density ($J_{sc}$), fill factor (FF), and open circuit voltage ($V_{oc}$) of the device with PFTQT were $0.97mA/cm^2$, 29% and 0.86 V, and the device based on PPTTQT were $0.80mA/cm^2$, 28% and 0.71 V, 31% and 0.71 V, respectively, under air mass (AM) 1.5 G and 1 sun condition ($100mA/cm^2$).