• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.116-116
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• 2009

$TiO_2$ pastes was synthesized to obtained of high efficiency dye-sensitized solar cells using size dependent co-polymer. SBM co-polymer binder is consist of styrene, n-butyl acrylate, and methacrylic acid (SBM) monodisperse co-polymer binder materials and this $TiO_2$ pastes were applied of dye-sensitized solar cells (DSSCs). The photoanodes were characterized by ATR-Fourier Transform spectrometer, X-ray diffraction (XRD) and morphology was investigated by field emission scanning electron microscopy (FE-SEM). The photoelectrochemical properties of the thin films and the performance of DSSCs were measured by photovoltaic-current density, AC impedance and monochromatic incident photon-to-current conversion efficiency (IPCE). DSSC based on the 100nm size co-polymer binder was obtained conversion efficiency of 8.1% under irradiation of AM 1.5(100 $mWcm^2$).

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.672-672
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• 2013

본 연구에서는 수열합성법을 기반으로 한 3차원 ZnO 나노구조의 합성을 통해 효율적인 양자점 감응형 태양전지로의 응용을 하고 그 특성을 평가하였다. 기존의 1차원 ZnO 나노구조의 경우 높은 전자이동도와 구조적으로 얻을 수 있는 방향성 있는 전자의 효율적인 전달을 통해 효과적인 광전극으로 많은 관심을 받아왔다. 하지만 나노파티클 기반의 필름에 비해 표면적이 크게 떨어지기 때문에 효과적인 흡광이 어렵다는 단점이 존재하여 높은 효율특성을 내지는 못하였다. 본 연구에서는 이러한 단점을 극복하면서 기존 ZnO 나노선의 장점을 극대화 하기 위해 성장시킨 ZnO 나노선 위에 추가적으로 가지를 형성하여 표면적 향상과 효과적인 전자전달 특성을 얻고자 하였다. 3차원 ZnO 나노구조는citrate 계열의 capping agent의 첨가를 통한 수열 합성법을 통해 1차원의 ZnO 나노선 위에 nanosheet 형식의 가지를 형성하였고 이는 빛의 효과적인 산란특성 및 표면적 향상을 통한 CdS, CdSe의 양자점 증착량을 증가시키는 효과를 얻을 수 있었다. 이러한 태양전지의 소자 특성은 SEM, TEM을 통한 구조 특성평가 및 DRS, J-V curve 및 IPCE를 통한 광학적 특성평가를 통해 확인하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1204-1207
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• 2009

We investigated the device performance of bulk heterojunction solar cells depending on the active layer thickness. For the systematic comparison, the polymer solar cells comprising RR-P3HT:PCBM (1:0.8 (wt%:wt%)) blend films with different thickness were characterized by impedance spectroscopy, and J-V measurement in dark and solar simulated illumination. The device with 120 nm thickness of active layer exhibited maximum power conversion efficiency of 3.5 % under AM 1.5 100mW/$cm^2$ illumination condition.

• Bulletin of the Korean Chemical Society
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• v.24 no.10
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• pp.1501-1504
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• 2003

Single-wall carbon nanotubes (SWCN) were integrated in $TiO_2$ film and the beneficial influence on the dyesensitized solar cells in terms of improved photocurrent was studied in the light of static J-V characteristics obtained both under illumination and in the dark, photocurrent transients, IPCE spectra and impedance spectra. Compared with a solar cell without SWCN, it is established that the photocurrent density of the modified cell increases at all applied potentials. The enhanced photocurrent density is correlated with the augmented concentration of electrons in the conduction band of $TiO_2$ and with increased electrical conductivity. Explanations are additionally corroborated with the help of SEM, Raman spectra and dye-desorption measurements.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.316-316
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• 2010

Six metal-free organic dyes having thiophene (1), benzene-thiophene (2), thiophene-benzene (3), thiophene-pyridine(4), thiophene-thiophene (5), and pyridine (6) linkers between 9,9-dimethylfluorenyl terminal group and $\alpha$-cyanoacrylic acid anchor were synthesized. Among them, organic dye 5 showed the longest ${\lambda}}max$ value (424 nm) in UV-Vis absorption spectrum, better incident monochromatic photon-to-current conversion efficiency (IPCE), highest short circuit photocurrent density (JSC, 9.33 mA2/cm2), and highest overall conversion efficiency ($\eta$, 3.91%).

• Bulletin of the Korean Chemical Society
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• v.21 no.10
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• pp.1047-1048
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• 2000

Dye-sensitized nanocrystalline rutile $TiO_2$ solar cells were prepared, and the influence of Li+ and 1,2-dimethyl-3-hexyl imidazolium ions in the electrolyte on the photovoltaic properties was compared. The electrolyte con-taining Li+ ions produced a lower open-circuit photovoltage than the electrolyte with 1,2-dimethyl-3-hexyl im-idazolium ions, suggesting that the adsorption of Li+ ions to the rutile $TiO_2$ surface causes a shift in the band edges toward more positive potentials. At the same time, both the short-circuit photocurrent and the maximum value of the incident-photon-current conversion efficiency (IPCE) of the electrolyte containing Li+ ions were relatively higher. Data analysis suggests that presence of adsorbed Li+ ions improves via the phenomenon of band-edge movement the charge-injection efficiency by altering both the energy and number of excited state levels of the dye that participate in electron injection.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.77.1-77.1
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• 2010

반도체 나노 결정은 크기와 모양에 따라 다른 광학적 전기적 성질을 보이는 독특한 특성 때문에 태양전지, 발광 다이오드, 레이저, 바이오메디컬 레이블링 등에 응용될 수 있는 저가격의 차세대 광전기 재료의 개발을 위한 구조체로 각광받고 있다. 최근에는 하나의 나노 결정에 type-II band offset을 가지는 두 개의 물질을 결합한 이종접합 나노 결정체의 연구가 활발하게 진행되고 있는데, 이는 나노 결정 내에서 빛에 의해 생성된 전하들을 공간적으로 분리해 낼 수 있는 장점을 가지고 있기 때문에 태양전지나 광촉매로의 응용에 매우 유용하다. 우리는 나노 결정과 고분자 하이브리드 태양전지의 제작에 있어서 성분과 type-II 이종접합 반도체 나노 결정의 영향을 조사하기 위하여 CdSe, CdTe, type-II CdTe/CdSe tetrapod을 합성하였다. CdSe tetrapod과 P3HT의 블렌딩에 의해 만들어진 태양전지는 AM 1.5, 100mW/$cm^2$ 조건에서 1.03%의 가장 높은 변환 효율, 그리고 415nm에서 43%의 IPCE를 나타내었다. 그리고 CdTe/CdSe type-II tetrapod 이종접합과 P3HT 블렌딩으로 만들어진 태양전지는 CdTe를 이용하여 만든 태양전지에 비해 4.4배의 변환효율과 3.9배의 단락전류를 나타내었다.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.3043-3047
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• 2012

To investigate the scattering layer effect of a $TiO_2$ multilayer in dye-sensitized solar cells (DSSCs), we designed a new DSSC system, assembled with a CdS-$TiO_2$ scattering layer electrode. A high-magnification SEM image exhibited hollyhock-like particles with a width of 1.5-2.0 ${\mu}m$ that were aggregated into 10-nm clumps in a hexagonal petal shape. The efficiency was higher in the DSSC assembled with a CdS-$TiO_2$ scattering layer than in the DSSC assembled with $TiO_2$-only layers, due to the decreased resistance in electrochemical impedance spectroscopy (EIS). The short-circuit current density ($J_{sc}$) was increased by approximately 7.26% and the open-circuit voltage ($V_{oc}$) by 2.44% over the 1.0 wt % CdS-$TiO_2$ composite scattering layer and the incident photon-to-current conversion efficiency (IPCE) in the maximum peak was also enhanced by about 5.0%, compared to the DSSC assembled without the CdS-$TiO_2$scattering layer.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.3
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• pp.588-593
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• 2010

Sputter deposition on a Pt counter electrode was studied using radio frequency (RF) plasma as the improvement of incident photon to current conversion efficiency (IPCE) for dye-sensitized solar cells (DSCs). Effects of the sputtering thickness and the incident angle on a Pt counter electrode for DSCs were investigated. Experiments to get the optimal sputtering time for the performance of the DSCs were carried out. And it is found that the optimized sputtering time was 120 seconds, in addition, the incident angles of the substrate was adjusted from $0^{\circ}$ to $60^{\circ}$. The maximum efficiency of 5.37% was obtained at the incident angle of $40^{\circ}$ with an active cell area of $1cm^2$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.662-662
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• 2013

Over the last several decades, innovative light-harvesting devices have evolved to achieve high efficiency in solar energy transfer. Research on the mechanisms for plasmon resonance is very desirable to overcome the conventional efficiency limits of photovoltaics. The influence of localized surface plasmon resonance on hot electron flow at a metal-semiconductor interface was observed with a Schottky diode composed of a thin silver layer on $TiO_2$. The photocurrent is generated by absorption of photons when electrons have enough energy to travel over the Schottky barrier and into the titanium oxide conduction band. The correlation between the hot electrons and the surface plasmon is confirmed by matching the range of peaks between the incident photons to current conversion efficiency (IPCE, flux of collected electrons per flux of incident photons) and UV-Vis spectra. The photocurrent measured on Ag/$TiO_2$ exhibited surface plasmon peaks; whereas, in contrast to the Au/$TiO_2$, a continuous Au thin film doesn't exhibit surface plasmon peaks. We modified the thickness and morphology of a continuous Ag layer by electron beam evaporation deposition and heating under gas conditions and found that the morphological change and thickness of the Ag film are key factors in controlling the peak position of light absorption.