• Applied Science and Convergence Technology
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• 제24권5호
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• pp.151-155
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• 2015

The interfacial electronic structure between zinc phthalocyanine (ZnPc) and aluminumdoped zinc oxide (AZO) substrates has been evaluated by ultraviolet photoemission spectroscopy and angle-dependent x-ray absorption spectroscopy to understanding the molecular orientation of a ZnPc layer on the performance of small molecule organic photovoltaics (OPVs). We find that the ZnPc tilt angle improves the ${\pi}-{\pi}$ interaction on the AZO substrate, thus leading to an improved short-circuit current in OPVs based on phthalocyanine. Furthermore, the molecular orientation-dependent energy level alignment has been analyzed in detail using ultraviolet photoemission spectroscopy. We also obtained complete energy level diagrams of ZnPc/AZO and ZnPc/indium thin oxide.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.190.1-190.1
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• 2014

The interfacial electronic structure of a bilayer of chloroaluminum phthalocyanine (ClAlPc) and pentacene grown on indium tin oxide (ITO) has been studied using synchrotron radiation-excited photoelectron spectroscopy. The energy difference between the highest occupied molecular orbital (HOMO) level of the pentacene layer and the lowest unoccupied molecular orbital (LUMO) level of the ClAlPc layer (EDHOMO - EALUMO) was determined and compared with that of C60/pentacene bilayers. The EDHOMO - EALUMO of a heterojunction with ClAlPc was found to be 1.4 eV, while that with C60 was 1.0 eV. This difference is discussed in terms of the difference of the ionization energy of each acceptor materials. We also obtained the complete energy level diagrams of ClAlPc/pentacene/ITO and C60/pentacene/ITO, respectively.

• Investigative Magnetic Resonance Imaging
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• 제4권2호
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• pp.128-135
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• 2000

목적 자기공명 스펙트럼 데이터의 처리 및 분석을 특정 workstation이 아닌 일반 PC의 windows 운영체제에서 동작할 수 있도록 GUI(Graphical User Interface)기반의 Spectroscopy 분석용 도구를 개발하였다. 대상 및 방법 S/W의 개발은 MATLAB(Mathwork사 미국)을 이용하여 PC의 window운영 체제에서 GUI 기반으로 동작하게 하였다. 시간 영역의 raw data와 주파수 영역의 spectrum data를 동시에 display할 수 있게 하였으며 Zero filling, 여러 종류의 filtering, 위상보정, FFT, peak area 측정 등의 기능을 갖추었다. 또한, 1.5T Gyroscan ACS-NT R6(Philips, Amsterdam, Netherland)의 $^1H$ Spectroscopy 패키지를 이용하여 정상인 뇌의 Parietal white matter, Basal ganglia, Occipital grey matter 영역에서 얻은 $^1$H MRS data를 정성 .정량적으로 분석하여 타 기종에서 얻어 발표된 $^1H$ MRS data와 비교분석하였다. 결과 : 본 연구에서 개발된 S/W를 이용하여 정상인 뇌에서 $^1H$ MRS data를 processing한 결과 NAA/Cr, Cho/Cr, MI/Cr 비율은 TE를 달리하였을 때, 유의수준 5%에서 Parietal white matter(PWM)의 NAA/Cr peak ratio를 제외하고 유의한 차이가 없었다. 그리고 기존에 발표된 문헌과 비교할 때 다른 MR장치의 NAA/Cr, Cho/Cr, MI/Cr 값들에 비해 평균값과 표준편차가 전반적으로 10-50%의 큰 값을 나타내었다. 결론 : 정상인 뇌에서 세 부위에 대하여 $^1H$ MRS를 얻고 이에 대한 정성.정량 분석을 함으로써 MRS를 임상적으로 적용하기 위한 준비를 하였으며 이러한 작업을 PC에서 독립적으로 수행함으로서 MRI system의 작업효율을 향상시킬 수 있었다. 그리고 서로 다른 기종간에는 유의한 차이가 있으므로 정상인에 대한 MRS database를 구축한 후에 $^1H$ MRS를 임상에 적용해야 함을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.66-66
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• 2009

The photoconductive $CdGa_2Se_4$ layer was grown through the hot wall epitaxy method. From the photocurrent (PC) measurements, the three peaks in the PC spectra were associated with the band-to-band transitions. The PC intensities were observed to decrease with decreasing temperature. The valence-band splitting on $CdGa_2Se_4$ was also observed by means of the PC spectroscopy. The crystal field splitting and the spin orbit splitting turned out to be 0.1604 and 0.4179 eV at 10 K, respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.114.2-114.2
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• 2014

The orientation of the constituent molecules in organic thin film devices can affect significantly their performance due to the highly anisotropic nature of ${\pi}$-conjugated molecules. We report here an angle dependent x-ray absorption study of the control of such molecular orientation using well-ordered interlayers for the case of a bilayer heterojunction of chloroaluminum phthalocyanine (ClAlPc) and C60. Furthermore, the orientation-dependent energy level alignment of the same bilayer heterojunction has been measured in detail using synchrotron radiation-excited photoelectron spectroscopy. Regardless of the orientation of the organic interlayer, we find that the subsequent ClAlPc tilt angle improves the ${\pi}-{\pi}$ interaction at the interface, thus leading to an improved short-circuit current in photovoltaic devices based on ClAlPc/C60. The use of the interlayers does not change the effective band gap at the ClAlPc/C60 heterointerface, resulting in no change in open-circuit voltage.

• Applied Science and Convergence Technology
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• 제23권6호
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• pp.351-356
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• 2014

The electronic structure at organic-organic interface gives essential information on device performance such as charge transport and mobility. Especially, the molecular orientation of organic material can affect the electronic structure at interface and ultimately the device performance in organic photovoltaics. The molecular orientation is examined by the change in ionization potential (IP) for metal phthalocyanines (MPc, M=Zn, Cu)/fullerene ($C_{60}$) interfaces on ITO by adding the CuI templating layer through ultraviolet photoelectron spectroscopy measurement. On CuPc/$C_{60}$ bilayer, the addition of CuI templating layer represents the noticeable change in IP, while it hardly affects the electronic structure of ZnPc/$C_{60}$ bilayer. The CuPc molecules on CuI represent relatively lying down orientation with intermolecular ${\pi}-{\pi}$ overlap being aligned in vertical direction. Consequently, in organic photovoltaics consisting of CuPc and $C_{60}$ as donor and acceptor, respectively, the carrier transport along the direction is enhanced by the insertion of CuI templaing layer. In addition, optical absorption in CuPc molecules is increased due to aligned transition matrix elements. Overall the lying down orientation of CuPc on CuI will improve photovoltaic efficiency.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.142.2-142.2
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• 2016

The metal intercalation to an organic semiconductor is of importance since the charge transfer between a metal and an organic semiconductor can induce the highly enhanced conductivity for achieving efficient organic electronic devices. In this regard, the changes of the electronic structure of copper phthalocyanine (CuPc) caused by the intercalation of potassium are studied by ultraviolet photoemission spectroscopy (UPS) and density functional theory (DFT) calculations. Potassium intercalation leads to the appearance of an intercalation-induced peak between the highest molecular occupied orbital (HOMO) and the lowest molecular unoccupied orbital (LUMO) in the valence-band spectra obtained using UPS. The DFT calculations show that the new gap state is attributed to filling the LUMO+1, unlike a common belief of filling the LUMO. However, the LUMO+1 is not conductive because the ${\pi}$-conjugated macrocyclic isoindole rings on the molecule do not make a contribution to the LUMO+1. This is the origin of a metal-insulator transition through heavily potassium doped CuPc.

• 통합자연과학논문집
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• 제9권4호
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• pp.275-280
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• 2016

Intensity modulated photovoltage spectroscopy (IMVS) analysis of organic solar cells (OSCs) with a bulk-heterojunction (BHJ) film composed of P3HT and $PC_{61}BM$ was performed. The dynamic response of charge recombination by the post-annealing approach in $P3HT/PC_{61}BM$ BHJ solar cells characterized by IMVS demonstrated that post-annealing reduced the recombination of electron carriers in the device. The recombination times of $P3HT/PC_{61}BM$ BHJ solar cells post-annealed at room temperature, 80, 120, and $140^{\circ}C$ were 0.009, 0.020, 0.024, and 0.030 ms, respectively, at a short-circuit current of 0.18 mA. The results indicated that the IMVS analysis can be effectively used as powerful.

• Bulletin of the Korean Chemical Society
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• 제28권4호
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• pp.557-560
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• 2007

The metabolic discrimination of safflowers from various geographical origins was performed using 1H nuclear magnetic resonance (NMR) spectroscopy followed by principal components analysis. With a combination of these techniques, safflower samples from different origins could be discriminated using the first two principal components (PC) of the 1H NMR spectra of the 50% methanol fractions. PC1 and PC2 accounted cumulatively for 91.3% of the variation in all variables. The major peaks in the 1H NMR spectra that contributed to the discrimination were assigned to fatty acid (terminal CH3), lactic acid, acetic acid, choline derivatives, glycine, and safflower yellow derivatives. In this study, we suggest that various types of safflower can be discriminated using PCA and 1H NMR spectra.

• 한국자기학회지
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• 제23권6호
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• pp.184-187
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• 2013

MgO 기반 스핀소자에 유기장벽 Cu-Phthalocyanine(CuPc)가 삽입된 무기${\backslash}$유기 터널 접합 소자 Fe${\backslash}$MgO(001)${\backslash}$CuPc${\backslash}$Co의 자기 저항 현상과 그 계면 특성의 상관관계에 대한 연구가 진행되었다. 특히 1.6 nm MgO(001)${\backslash}$x nm CuPc(x = 0~5) 계면의 전자기적 특성을 스핀 편극된 준안정상태 He 원자 분광계(Metastable Helium De-excitation Spectroscopy, MDS)를 이용하여 규명하였다. 에피 성장된 MgO(001) 위에 적층된 약 1.6 nm 두께의 CuPc 층상구조의 표면에서, MgO(001) 하지층의 표면과는 달리, up-spin band와 down-spin band의 비대칭성이 현저해지는 것으로 관찰되었다. 이 결과는 실온과 저온(77 K)에서 ~10 %와 30 %로 각각 측정된 자기저항 현상과 복합장벽을 통과하는 스핀거동을 이해하는데 중요한 단초를 제공해 준다.