• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.107-113
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• 2009

In order to improve air stability, we proposed a new active layer of an organic TFT by synthesizing P3HT/POSS conjugated polymer. P3HT/POSS OTFTs with the various P3HT/POSS volume ratios were fabricated and characterized. With the P3HT/POSS volume ratio of 1:1, we achieved the field-effect mobilities of ${\sim}1.19{\times}10^{-3}\;cm^2/v{\cdot}sec$ in the saturation region and the current on/off ratio of ${\sim}2.51{\times}10^2$. The resulting current on-off ratio was much higher than that of the P3HT-based OTFTs and resulted from the dramatic decrease of the off-current. Since the off-current can be reduced by preventing oxygen in atmosphere from doping the P3HT/POSS active layers, this new active layer shows its ability to avoid oxygen doping in atmosphere. Therefore, the improvement of the air stability can be achieved by employing the P3HT/POSS active layers.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.278-278
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• 2010

3.37 eV의 와이드 밴드갭과 60 mV의 높은 엑시톤 결합에너지를 갖는 반도체인 ZnO는 화학 및 열적 안정성, 압전특성 등 다양한 특성을 갖는 물질로써, 수열합성법을 이용하여 길이 $1.5{\mu}m$, 직경 100nm의 n-type ZnO 나노와이어를 성장시켰으며, P3HT는 유기 태양전지에서 가장 많이 사용되는 고분자 도너로써 열처리를 통하여 결정화 됨에 따라, 엑시톤의 확산속도나 전하의 이동도가 증가하여 더 많은 광전류를 생성하는 장점을 가지고 있다. 본 연구에서는 ZnO 필름이 아닌 n-type ZnO 나노와이어와 Poly(3-hexylthiophene) (P3HT)를 사용 하여 ZnO/P3HT 이종접합 태양전지를 제작하였다. 기판으로 글래스, 전극으로 ITO (Indium Tin Oxide), 나노와이어의 씨앗층으로 ZnO:Al를 스퍼터로 100nm 증착 하였다. Znc nitrate hydrate와 hexamethylenetetramine이 혼합된 수용액에서 기판을 담그고 n-type ZnO 나노와이어 성장 시키고, P3HT의 스핀 코팅조건과 열처리 온도를 변화시켜 P3HT의 두께와 결정화도가 ZnO/P3HT 이종접합 태양전지에 미치는 영향을 비교 분석 하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.460-461
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• 2009

We studied the effects of post-annealing treatment on poly(3-hexylthiophene)(P3HT, donor):[6,6]-phenyl $C_{61}$ butyric acid methyl ester(PCBM, acceptor) blend film as an active layer in the organic solar cells(OSCs). For the formation of the active layer, 3 wt.% P3HT:PCBM solution in chlorobenzene were deposited by spin-coating method. In order to optimize the performance of OSCs, the P3HT crystallization and the redistribution of PCBM cluster at P3HT:PCBM composition as a function of post-annealing condition from room temperature to $200^{\circ}C$ were measured by the Hall effect and the UV-vis Spectrophotometer. We thought that the improved efficiency in the OSCs with post-annealing treatment at $150^{\circ}C$ can be explained by the efficient separation or collection of the photogenerated excitons at donor-acceptor interface by P3HT crystallization.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1018-1021
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• 2003

We have synthesized poly(3-hexylthiophene) and studied the optical properties of P3HT for applying to the red emitting materials of organic electroluminescent device. Usually, an organic EL device is composed of single layer like anode/emitting layer/cathode, but additional layer such as hole transport, electron transport and buffer layer is deposited to improve device efficiency. In this study, Multilayer EL devices were fabricated using tris(8-hydroxyquinolinate) aluminum($Alq_3$) as electron transport material, (N,N'-diphenyl-N,,N'(3-methylphenyl)-1,1'-biphenyl-4,4'diamine))(TPD) as hole transport/electron blocking materials and LiF as buffer layer. That is, a device structure of ITO/blending layer(TPD+P3HT)/$Alq_3$/LiF/Al was employed. In the Multilayer device, the luminance of $10{\mu}W/cm^2$ obtained at 10V. And, we present the experimental evidence of the enhancement of the Foster energy transfer interaction in emitting layer.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1647-1653
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• 2014

9,10-Bis(bromomethyl)phenanthrene reacted with fullerenes via a Diels-Alder reaction to give phenanthrene-substituted fullerene mono-adducts (PCMA) and bis-adducts (PCBA) as electron acceptors for organic photovoltaic cells (OPVs). The syntheses of the fullerene derivatives were confirmed by $^1H$ $^{13}C$ NMR spectroscopy and MALDI-TOF mass spectrometry. PCMA and PCBA showed better light absorption in the UV-visible region than $PC_{61}BM$. Their electrochemical properties were measured using cyclic voltammetry. Accordingly, the lowest unoccupied molecular orbital (LUMO) energy levels of PCMA and PCBA were -3.66 and -3.57 eV, respectively. Photovoltaic cells were fabricated with a ITO/PEDOT:PSS/poly(3-hexylthiophene)(P3HT):acceptor/LiF/Al configuration, where P3HT and PCBA are the electron donors and acceptors, respectively. The polymer solar cell fabricated using the P3HT:PCBA active layer showed a maximum power conversion efficiency of 0.71%.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2995-3004
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• 2013

The structural, electronic, and optical properties of poly(3-hexylthiophene) (P3HT) have been comprehensively studied by density functional theory (DFT) to rationalize the experimentally observed properties. Rather, we employed periodic boundary conditions (PBC) method to simulate the polymer block, and calculated effective charge mass from the band structure calculation for describing charge transport properties. The simulated results of P3HT are consistent with the experimental results in band gaps, absorption spectra, and effective charge mass. Based on the same calculated methods as P3HT, a series of polymers have been designed on the basis of the two types of building blocks, furofurans and furofurans substituted with cyano (CN) groups, to investigate suitable polymers toward polymer solar cell (PSC) materials. The calculated results reveal that the polymers substituted with CN groups have good structural stability, low-lying FMO energy levels, wide absorption spectra, and smaller effective masses, which are due to their good rigidity and conjugation in comparison with P3HT. Besides, the insertion of CN groups improves the performance of PSC. Synthetically, the designed polymers PFF1 and PFF2 are the champion candidates toward PSC relative to P3HT.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.88-93
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• 2008

The bulk-heterojunction polymer solar cell based on regioregular P3HT (poly(3-hexylthiophene)) and PCBM (methanofullerene [6,6]-phenyl $C_{61}$-butyric acid methyl ester) was fabricated. Annealing effects on the crystal structure of polymer-fullerene blends as well as the UV-VIS electronic absorption spectroscopy were investigated. The correlation between the crystal organization of bulk-heterojunction film and the power conversion efficiency of solar cell was studied. Resultantly, the polymer solar cell annealed on $150^{\circ}C$ for 30 min, showed both the enhanced molecular interactions and the optimized crystal structure and displayed the power conversion efficiency of 3.2 %.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1128-1134
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• 2012

We investigated a new method for patterning organic field-effect transistors (OFETs) using a photopatternable conducting polymer nanocomposite, consisting of poly(3-hexylthiophene) (P3HT)-coated gold nanoparticles (AuNPs) that had been modified with a photoreactive cinnamate group, to form P3HT-AuNP-CI. We found that the addition of the cinnamate group to the nanoparticle surface assisted the preparation of a solvent-resistive semiconducting film and preserved the P3HT ordering, which was interrupted by Au-P3HT interactions, as well as provided UV-controllable electrical properties. The P3HT-AuNPs-CI films could be microscale-patterned via a UV crosslinking photoreaction, represented as a promising photopatternable semiconductor material for use in advanced applications, with tunable electrical properties for fabrication of sub-micron and microscale electronic devices.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.3
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• pp.252-256
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• 2013

We introduced sensitizing dyes into the bulk-heterojunction (BHJ) photovoltaic (PV) layer of polymer solar cells (PSCs). The sensitizing dyes doped were Bis(tetra butyl ammonium) cis-dithio cyanato bis(2,2'-bipyridine-4-carboxylicacid-4'-carboxylate) ruthenium (II) (N719 dye) and the BHJ PV layer used was made of poly (3-hexylthiophene) (P3HT) and phenyl $C_{61}$-butyric acid methyl ester (PCBM). It was found that the N719 dyes increase the photovoltaic performance, i.e., increasing open-circuit voltage and short-circuit current density with improved fill factor. For the P3HT:PCBM PV cells doped with the N719 dyes (0.24 wt%), an increase in power conversion efficiency of 4.0% was achieved, compared to that of the control cells (3.6%) without the N719 dyes.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1243-1244
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• 2007

전자주개물질 (elelctron donating material)인 poly(3-hexylthiophene) (P3HT)와 전자받개물질 (electron accepting material)인 티타니아 ($TiO_2$)를 이용한 복합형 태양전지에 대해 연구하였다. 유기물 태양전지에 응용되는 전도성 고분자의 여기자 (exiton)의 확산거리가 매우 짧기 때문에 그것을 보완하기 위해 전자주개물질과 받개물질의 표면적을 넓힐 필요가 있다. 비교적 패턴을 형성하기 쉬운 무기물인 티타니아를 이용해 표면적을 증가시켰으며 그렇지 않은 태양전지에 비해 효율이 두 배 증가하는 것을 볼 수 있었다. 티타니아의 표면적을 증가시킨 태양전지의 개방회로전압 ($V_{oc}$), 단락회로전류 ($I_{sc}$), FF (fill factor) 및 효율 (${\eta}$)은 각각 560 mV, 0.657 mA, 48.3 %, 0.18% 이다.