• 반도체디스플레이기술학회지
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• 제22권1호
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• pp.33-38
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• 2023

As the demand for large flexible displays such as tablet computers continues to rise, there is an increasing need for cost-efficient colorless and optically transparent polyimide film that can meet the desired performance, particularly optical transmittance. In this study, we investigated a detailed procedure for achieving optimal optical transmittance using two different combinations of monomers: 6FDA+BAPB and 6FDA+BPA+TFDB. We employed a design of experiment method to systematically synthesize polymers, allowing for the optimization of optical transmittance. In addition, we were able to achieve uniform thickness in the films by using a doctor blade. By comparing the price and optical transmittance of four different monomer combinations, we obtained fundamental data on the production of polyimide films that can be customized to meet the specific price and performance requirements of manufacturers. This approach enables users to select the most suitable polyimide film based on their desired price and performance parameters while achieving optimal optical transmittance.

• 반도체디스플레이기술학회지
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• 제9권2호
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• pp.117-121
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• 2010

The composite films were fabricated by air-spray method under the 2 kgf/$cm^2$ pressure using the multi-walled CNTs solution and the nitrocellulose on a 10 ${\mu}m$ polyimide film substrates. We obtained the composite films which were sprayed with the MWCNT dispersion by varying the spray time from 20, 40 and 60sec. The electrical and the optical properties of the sandwiched-structure-composite thin films were investigated by an UV/VIS spectrometer and a Hall Effect equipment. As a result, the optical transmittance of all thin films in the visible range, as well as the electrical conductance shows an available value for the transparent electrode. The carrier concentration and the light transmittance rate for the fabricated sample are between $3.733{\times}10^{10}$ and $6.551{\times}10^{14}cm^{-3}$, around 35 to 95%, respectively.

• Elastomers and Composites
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• 제58권1호
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• pp.26-31
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• 2023

Aromatic diamine containing ortho catenation and methyl group was synthesized from 4-methyl catechol and 4-nitrobenzoyl chloride. Subsequently, a poly(amic acid) was prepared by reacting 4-methyl-1,2-phenylene bis(4-aminobenzoate) with 4,4'-hexafluoroisopropylidenediphthalic anhydride (6FDA). The resulting poly(amic acid) was transformed into a polyimide through chemical imidization. The polyimide formed was soluble in N-methyl-2-pyrrolidone (NMP) and could be cast into a flexible, transparent film. Furthermore, the polyimide exhibited a 5% weight loss at 380 ℃ in the nitrogen atmosphere.

• 한국전기전자재료학회논문지
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• 제19권12호
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• pp.1144-1148
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• 2006

We have investigated liquid crystal (LC) aligning capabilities and electro-optical (EO) characteristics of transparent electrodes as Al-doped ZnO (AZO) substituting indium tin oxide (ITO). The experiment results show that a uniform vertical LC alignment on AZO electrodes based on a rubbed polyimide (PI) surface were achieved. A high pretilt angle of about $88^{\circ}$ was obtained. EO performances of the VA cell on rubbed PI surfaces with AZO electrodes are almost the same as that of the VA cell with ITO electrodes. These results appeared that AZO electrodes as transparent electrodes of LCDs could substitute ITO electrodes.

• 공업화학
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• 제23권3호
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• pp.266-270
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• 2012

무수물인 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)에 2,2'-bis(trifluoromethyl)benzidine (TFB), 2,2'-bis(3-aminophenyl)hexafluoropropane (BAFP), 2,2'-bis(3-amino-4-methylphenyl)hexafluoropropane (BAMF), bis(3-aminophenyl) sulfone (APS), p-xylyenediamine (p-XDA), 및 m-xylyenediamine (m-XDA) 등 6종류의 각각 다른 아민 단량체를 이용하여 폴리이미드(PI) 필름을 제조하였다. 얻어진 무색 투명한 PI필름은 무수물과 아민을 반응시켜 폴리아믹산(PAA)을 합성한 후, 용액 캐스팅에 의한 열처리 과정을 통해 얻었다. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermo-mechanical analysis (TMA)를 이용하여 열적 성질을 측정하였고, universal tensile machine (UTM)을 이용하여 기계적 성질을 조사하였으며, 자외선/가시광선 분광광도계(UV-vis.)와 색차계를 이용하여 광학적 성질을 각각 확인하였다. 제조된 모든 필름들은 무색 투명하여 0.98~2.76 사이의 노란색 지수를 보였으며, 25.73~55.23 $ppm/^{\circ}C$사이의 열 팽창 계수를 나타냈다.

• 한국전기전자재료학회논문지
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• 제35권1호
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• pp.80-85
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• 2022

ZnO-based transparent conductive films have been widely studied to achieve high performance optoelectronic devices such as next generation flexible and transparent display systems. In order to achieve a transparent flexible ZnO-based device, a low temperature growth technique using a flexible polymer substrate is required. In this work, high quality flexible ZnO films were grown on colorless polyimide substrate using atomic layer deposition (ALD). Transparent ZnO films grown from 80 to 200℃ were fabricated with a metal-semiconductor-metal structure photodetectors (PDs). As the growth temperature of ZnO film increases, the photocurrent of UV PDs increases, while the sensitivity of that decreases. In addition, it is found that the response times of the PDs become shorter as the growth temperature increases. Based on these results, we suggest that high-quality ZnO film can be grown below 200℃ in an atomic layer deposition system, and can be applied to transparent and flexible UV PDs with very fast response time and high photocurrent.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.633-636
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• 2008

A series novel films of polyimide (PI) and co-polyimide (Co-PI) containing fluorine with colorless, flexible properties was prepared by a two-step process from various commercial aromatic monomers such as 4,4'-(Hexafluoro iso propylidene) diphthalic anhydride (6FDA), 2,2'-Bis(Trifluoromethyl) benzidine (TFDB), 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (AH6FP) and Bis(4-(3-aminophenoxy)phenyl)sulfone (BAS). Furthermore, these obtained transparent and flexible Co-PI films exhibited excellent thermal stability with the decomposition temperature (at 5% weight loss) around of $500^{\circ}C$ and the glass transition temperature ($T_g$) in the range of $275-350^{\circ}C$.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.393-395
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• 2009

We fabricated oxide and oxide/organic hybrid TFTs on a glass substrate using the photolithography process under $200^{\circ}C$. We adopt the solution processed organic ferroelectric materials of P(VDF-TrFE) and polyimide (KSPI) insulator for 1-T structure memory and flexible device, respectively. All devices have successfully operated and showed the possibility of hybrid TFTs for the application to the flexible electronic devices.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.857-860
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• 2002

The material that is both conductive in electricity and transparent to the visible-ray is called transparent conducting thin film. It has many field of application such as solar cell, liquid crystal display, transparent electrical heater, selective optical filter, and a optical electric device. In this study, indium tin oxide (ITO ; Sn-doped $In_2O_3$) thin films were deposited on $SiO_2$/soda-lime glass plates by a dc magnetron sputtering technique. The crystallinity and electrical properties of the films were investigated by X-ray diffraction(XRD), atomic force microscopy (AFM) scanning and 4-point probe. The optical transmittance of ITO films in the range of 300-1000nm were measured with a spectrophotometer. As a result, we obtained polycrystalline structured ITO films with (222), (400), and (440) peak. Transmittance of all the films were higher than 90% in the visible range.

• 반도체디스플레이기술학회지
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• 제21권1호
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• pp.79-84
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• 2022

As various flexible display products are released, the demand for high-performance colorless and transparent polyimide (CPI) film is continuously increasing. The primary purpose of this study is to establish a systematic procedure for optimizing the optical performance of CPI films by applying the response surface method. After selecting three key factors (monomer type, stirring time for varnish synthesis, and maximum temperature of vacuum furnace for film production) affecting optical performance based on experiences and references, CPI films were manufactured according to the experimental sequence designed by the central composite design, and then the yellowness index (YI) and optical transmittance (Tr) of the films were measured. When producing a CPI film by pouring varnish into a petri dish, the change in optical properties according to thickness should be considered, and there was a meaningful linear relationship between YI and Tr. The species of monomer and the maximum temperature were the critical factors that had an influence on YI and Tr, respectively. It is expected that the procedure proposed in this study can serve as a starting point for CPI film optimization studies considering the other factors that were not considered and responses such as thermal properties.