• Korean Chemical Engineering Research
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• 제49권3호
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• pp.352-356
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• 2011

리빙 프리 라디칼 중합법은 ATRP, NMP, RAFT 등의 방법이 있으며, 지난 수 십년간 매우 빠르게 발전해 왔다. 그 중에서 RAFT 중합법은 다른 방법들에 비해 최근에 학문적으로 크게 주목 받고 있다. RAFT 중합법은 다른 리빙 프리 라디칼 중합법에 합성할 수 있는 단량체의 종류나 합성의 제한이 비교적 작아서, 다양한 기능성 고분자를 쉽게 중합할 수 있으며, 합성한 고분자의 분자량 분포 또한 좁게 만들 수 있는 장점이 있다. 따라서 RAFT 중합법을 통해 다양한 형태의 블록 공중합체, 댄드리머 등을 합성하는데 이용되고 있다. 이 논문에서는 위와 같은 RAFT 중합법을 이용해, 친수성 블록을 갖는 새로운 블록 공중합체를 합성한다. Poly(ethylene-b-styrene)와 poly(ethylene-b-metharylate-bstyrene) 같은 블록 공중합체 박막을 이용해 용매 증발법에 의한 높은 수준의 정렬도를 갖는 연구가 진행, 보고되었다. 그리고 위의 2가지 연구에서 습도가 정렬도에 큰 영향을 미치는 것으로 보고되고 있다. 하지만 위의 연구에서 친수성 블록에 의한 영향을 명확하게 규명하지 못했다. 따라서 이 논문에서는 다른 친수성 블록을 갖는 poly(N,Ndimethylacrylamide-b-styrene)를 RAFT 중합법에 의해 합성하고, 이를 이용해 박막 내에서 용매 증발법 중의 습도에 의한 영향을 일반화하고자 한다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.36.2-36.2
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• 2009

In this work, the high power CW Nd:YAG laser has been used for thermal treatment of inkjet printed Ag films-involving eliminating organic additives (dispersant, binder, and organic solvent) of Ag ink and annealing Ag nanoparticles. By optimizing laser parameters, such as laser power and defocusing value, the laser energy can totally be converted to heat energy, which is used to thermal treatment of inkjet printed Ag films. This results in controlling the microstructures and the resistivity of films. We investigated the thermal diffusion mechanisms during laser annealing and the resulting microstructures. The impact of high power laser annealing on microstructures and electrical characteristic of inkjet printed Ag films is compared to those of the films annealed by a conventional furnace annealing. Focused ion beam (FIB) channeling image shows that the laser annealed Ag films have large columnar grains and dense structure (void free), while furnace annealed films have tiny grains and exhibit void formation. Due to these microstructural characteristics of laser annealed films, it has better electrical property (low resistivity) compared to furnace annealed samples.

• Transactions on Electrical and Electronic Materials
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• 제17권3호
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• pp.134-138
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• 2016

The fullerene solar cells are becoming a feasible choice due to the advanced developments in donor materials and improved fabrication techniques of devices. Recently, sufficient optimization and improvements in the processing techniques like incorporation of solvent vapor annealing (SVA) with additives in solvents has become a major cause of prominent improvements in the performance of organic solar cell-based devices . On the other hand, the challenge of reduced open circuit voltage (V_oc) remains. This study presents an approach for significant performance improvement of overall device based on organic small molecular solar cells (SMSCs) by following a two step technique that comprises thermal annealing (TA) and SVA (abbreviated as SVA+TA). In case of exclusive use of SVA, reduction in V_oc can be eliminated in an effective way. The characteristics of charge carriers can be determined by the measurement of transient photo-voltage (TPV) and transient photo-current (TPC) that determines the scope for improvement in the performance of device by two step annealing. The recovery of reduced V_oc is linked with the necessary change in the dynamics of charge that lead to increased overall performance of device. Moreover, SVA and TA complement each other; therefore, two step annealing technique is an appropriate way to simultaneously improve the parameters such as V_oc, fill factor (FF), short circuit current density (J_sc) and PCE of small molecular solar cells.

• Journal of Magnetics
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• 제6권1호
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• pp.1-4
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• 2001

We have used acetic acids ethanol and distilled water as a solvent to synthesize $La_{2/3}Sr_{1/3}Mn_{0.99}{^{57}}Fe_{0.01}O_3$(LSMFO) precursor. Crack-free LSMFO granular polycrystalline thin films have been deposited on thermally oxidized silicon substrates by spin coaling. The dependence of crystallization, surface morphology, magnetic and transport properties on annealing temperature was investigated. With increasing annealing temperature, the metal-semiconductor (insulator) transition temperature and the magnetic moment decrease while the resistivity increases. The lattice constants remain almost unchanged. For LSMFO thin films, spin-dependent interfacial tunneling and/or scattering magnetoresistance were observed. Our results indicate that the annealing temperature is very important in determining the intrinsic and extrinsic magnetotransport properties.

• 공업화학
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• 제23권3호
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• pp.289-292
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• 2012

용액공정이 가능한 저분자 유기반도체, triethylsilylethynyl anthradithiophene (TES ADT)을 기반으로 한 유기박막 트랜지스터에서 금 전극의 일함수를 제어하기 위해 표면을 자기조립 단분자막(self-assembled monolayers, SAMs)으로 개질하였다. Benzothiol (BT)과 pentafluorobenzothiol (PFBT) 자기조립 단분자막을 이용해 금 전극의 일함수를 조절하고 이를 통해 TES ADT의 HOMO 준위에 대한 정공주입장벽을 최소화 하고자 하였다. 또한, solvent annealing 후처리 공정을 통해 TES ADT 박막의 결정성을 향상시켰고, 이를 PFBT로 개질된 금 전극을 기반으로 한 유기박막 트랜지스터에 적용한 경우 $0.05\;cm^2/Vs$의 높은 전계효과 이동도와 $10^6$의 높은 점멸비를 보고하였다.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.1067-1070
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• 2011

We have demonstrated that solution-based fabrication of NiO films as HTL can be used for the construction of IOSCs. Type of solvent of NiO-solution, and annealing procedure of the active layers were optimized for obtaining a PCE of 3% of IOSC. The photovoltaic performance of NiO-based device is comparable to that of the same type of solar cell using PEDT:PSS instead of NiO. These solution-based processes can be a promising method for a mass production OSCs under ambient condition.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.318.1-318.1
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• 2016

Hafnium Oxide (HfOx) has been attracted as a promising gate dielectric for replacing SiO2 in gate stack applications. In this paper, Metal-Oxide-Semiconductor (MOS) capacitor with solution processed HfO2 high-k material as a dielectric were fabricated. The solvent using $HfOCl2{\cdot}8H2O$ dissolve in 2-Methoxy ethanol was prepared at 0.3M. The HfOx layers were deposited on p-type silicon substrate by spin-coating at $250^{\circ}C$ for 5 minutes on a hot plate and repeated the same cycle for 5 times, followed by annealing process at 350, 450 and $550^{\circ}C$ for 2 hours. When the annealing temperature was increased from 350 to $550^{\circ}C$, capacitance value was increased from 337 to 367 pF. That was resulted from the higher temperature of HfOx which have more crystallization phase, therefore dielectric constant (k) was increased from 11 to 12. It leads to the formation of dense HfOx film and improve the ability of the insulator layer. We confirm that HfOx layer have a good performance for dielectric layer in MOS capacitors.

• 한국분말재료학회지
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• 제24권2호
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• pp.102-107
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• 2017

Porous polytetrafluoroethylene (PTFE) thin films are fabricated by spin-coating using a dispersion solution containing PTFE powders, and their crystalline properties are investigated after thermal annealing at various temperatures ranging from 300 to $500^{\circ}C$. Before thermal annealing, the film is densely packed and consists of many granular particles 200-300 nm in diameter. However, after thermal annealing, the film contains many voids and fibrous grains on the surface. In addition, the film thickness decreases after thermal annealing owing to evaporation of the surfactant, binder, and solvent composing the PTFE dispersion solution. The film thickness is systematically controlled from 2 to $6.5{\mu}m$ by decreasing the spin speed from 1,500 to 500 rpm. A triboelectric nanogenerator is fabricated by spin-coating PTFE thin films onto polished Cu foils, where they act as an active layer to convert mechanical energy to electrical energy. A triboelectric nanogenerator consisting of a PTFE layer and Al metal foil pair shows typical output characteristics, exhibiting positive and negative peaks during applied strain and relief cycles due to charging and discharging of electrical charge carriers. Further, the voltage and current outputs increase with increasing strain cycle owing to accumulation of electrical charge carriers during charge-discharge.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.392.2-392.2
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• 2014

Poly (vinylidene fluoride) thin films were deposited by a spray-coating technology. Two organic solvents with different boiling point were used to prepare the mixture solution for spray coating process: N-Methylpyrrolodone ($B.P.=202^{\circ}C$); Tetrahydrofuran ($B.P.=66^{\circ}C$). Post-deposition annealing temperature was varied for the spray-coated Poly(vinylidene fluoride) thin films. Structural characteristics of the thin films were comparatively investigated by FT-IR and XRD in relation with the organic solvent and post-deposition annealing temperature.

• 대한전기학회논문지
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• 제43권6호
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• pp.965-970
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• 1994

ZnO transparent conducting oxide thin films have been prepared by Pyrosol deposition method and the effects of the different experimental variables on the electrical resistivity and optical transmittance of the prepared films have been investigated in details. The best film with a resistivity of about 8 X 10S0-2TΩcm and transmittance about 80% has been obtained at the substrate temperature of 4$25^{\circ}C$ by using HS12T+CHS13TOH(1:3) solvent and NS12T carrier gas after annealing at 20$0^{\circ}C$ for 40 minutes in vacuum. Furthermore, We have also found the effect of substrate temperature on crystallographic orientation and surface morphology. Annealing of the as-deposited film in vacuum leads to a substantial reduction in resistivity without affecting the optical transmittance and crystallographic orientation.