• Journal of Electrical Engineering and Technology
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• v.6 no.5
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• pp.684-687
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• 2011

In this study, we investigate the photovoltaic performance of transparent conductive indium tin oxide (ITO), titanium-doped indium oxide (ITiO), and fluorine-doped tin oxide (FTO) films. ITO and ITiO films are prepared by radio frequency magnetron sputtering on soda-lime glass substrate at $300^{\circ}C$, and the FTO film used is a commercial product. We measure the X-ray diffraction patterns, AFM micrographs, transmittance, sheet resistances after heat treatment, and transparent conductive characteristics of each film. The value of electrical resistivity and optical transmittance of the ITiO films was $4.15{\times}10^{-4}\;{\Omega}-cm$. The near-infrared ray transmittance of ITiO is the highest for wavelengths over 1,000 nm, which can increase dye sensitization compared to ITO and FTO. The photoconversion efficiency (${\eta}$) of the dye-sensitized solar cell (DSC) sample using ITiO was 5.64%, whereas it was 2.73% and 6.47% for DSC samples with ITO and FTO, respectively, both at 100 mW/$cm^2$ light intensity.

• Journal of the Korean Electrochemical Society
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• v.12 no.4
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• pp.301-310
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• 2009

This paper describes one of the hot issues in solar cell studies, dye-sensitized solar cell. DSSC is a kind of photoelectrochemical cells. Therefore, it is quite different from the conventional solar cells which originate from pn semiconductor theory, although its mechanism can be explained with the theory. This paper describes the difference between the conventional semiconductor approaches and a newly adapted one for DSSC. Especially, electrochemical analysis methods such as electrochemical impedance analysis and cyclic voltammogram are briefly introduced, which are commonly used for DSSC analysis.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.120.2-120.2
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• 2011

The improvement of solar energy-to-electricity conversion efficiency has continued to be an important research area of dye-sensitized solar cells (DSSCs). The mechanism of DSSCs is based on the injection of electrons from the photoexcited dye into the conduction band of nanocrystalline TiO2 or ZnO. Thus, the electronic structures, such as HOMO, LUMO, and HOMO-LUMO band gaps of dye moleculed in DSSC are deeply related to the electron transfer by photoexcitation and redox potential. Organic dyes, because of their many advantages, such as high molar extinction coefficients, convenience of customized molecular design for desired photophysical and photochemical properties, inexpensiveness with no transition metals contained, and environment-friendliness, are suitable as photosensitizers for DSSC. We believe that practically useful organic dye photosensitizers can be produced by exploiting electron donor/acceptor system with proper length of ${\pi}$-conjugation in a chromophore to control the absorption wavelength and enhance the photovoltaic performance. In this research, We designed and synthesized organic dyes also investigated the photoelectrochemical properties of a series of ionic dyes in DSSCs.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4382-4386
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• 2011

$TiO_2$ hollow spheres were fabricated by using $SiO_2$ as an inorganic template. Spherical $SiO_2$ particles were coated by $TiO_2$ through the nucleation process, and then the core $SiO_2$ part was eliminated by using HF solution. Finally, $TiO_2$ hollow spheres were obtained. The size of the $TiO_2$ hollow spheres was about 300-400 nm and the thickness of the hollow wall was about 20-30 nm. The hollow has several holes whose diameters were within 100-200 nm. Dye-sensitized solar cells fabricated by using the $TiO_2$ hollow spheres were characterized. The solar conversion efficiency of the cell was 8.45% when $TiO_2$ hollow spheres were used as a scattering material, while it was 4.59% when $TiO_2$ hollow spheres were used as a normal electrode material.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.294-294
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• 2010

Over the last decade, dye-sensitized solar cell (DSSC) has attracted much attention due to the high solar-to-electricity conversion efficiency up to 10% as well as low cost compared with p-n junction photovoltaic devices. DSSC is composed of mesoporous TiO2 nanoparticle electrodes coated with photo-sensitized dye, the redox electrolyte and the metal counter electrode. The performances of DSSC are dependent on constituent materials and interface as well as device structure. Replacing the heavy glass substrate with plastic materials is crucial to enlarge DSSC applications for the competition with inorganic based thin film photovoltaic devices. One of the biggest problems with plastic substrates is their low-temperature tolerance, which makes sintering of the photoelectrode films impossible. Therefore, the most important step toward the low-temperature DSSC fabrication is how to enhance interparticle connection at the temperature lower than $150^{\circ}C$. In this talk, the key issues for high efficiency plastic solar cells will be discussed, and several strategies for the improvement of interconnection of nanoparticles and bendability will also be proposed.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.150-152
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• 2009

본 연구는 염료감응형 태양전지에 적용되는 TiO2 나노입자를 개선하여 3차원적인 nanobranch를 수열법으로 합성하여 전자의 이동을 향상시키며, 비표면적을 늘려 효율향상을 위하여 전극 구조를 제어하였다. nanobranch의 seed인 nanowire를 XRDd, FE-TEM과 solar simulator를 이용하여 비교 분석하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4925-4929
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• 2015

Dye-sensitized solar cell(DSSC) has aroused intense interest owing to its competitive price and stabilized properties than Si based solar cells. Recently, many studies have been reported on the DSSC, especially development of a transparent conductive oxide-less dye-sensitized solar cell(TCO-less DSSC). In this paper, a thick and porous Ti electrode for low cost DSSC developed its properties. To estimate the Ti electrode, the films are tested FESEM and J-V evaluation method. An increase in Ti thickness from 50 nm to 200 nm mainly affects the fill factor without noticeably changing the photocurrent density. It was confirmed that optimal DSSC efficiency was obtained at Ti 150 nm.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.360.1-360.1
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• 2014

DSSC (Dye-Sensitized Solar Cell)의 TCO (Transparent Conductive Oxide)와 전해질 사이의 전자 재결합(Back reaction)은 DSSC의 효율을 떨어뜨리는 요소 중 하나이다. 이와 같은 문제점을 해결하기 위하여 Blocking layer로서 $TiO_2$ 가 많이 사용되어지고 있다. 본 실험에서는 $HfO_2$ 를 Blocking layer로 사용하여 전자 재결합으로 인한 효율 저하를 막기 위한 연구를 진행하였다. 기존 $TiO_2$ 대비 $HfO_2$는 큰 에너지 밴드갭을 가지고 있어, TCO와 전해질 사이에 전자 재결합을 줄여주는 역할을 하기 때문에 DSSC의 효율 향상을 확인할 수 있다. 효율 측정은 1sun (100 mW/cm, AM1.5)조건에서 solar simulator를 이용하여 측정 했으며, 전자 재결합 감소는 Dark Current, EIS (Electrochemical Impedance spectroscopy)의 측정을 통하여 확인하였다. $HfO_2$를 이용한 blocking layer를 염료 감응 태양전지에 적용하면, 전자 재결합에 의한 손실을 줄여 성능적 측면에서 개선 가능할 것으로 생각된다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.988-993
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• 2004

Luminescence characteristics of Ag-doped ZnO as the quantum dot materials to increasing the efficiency on dye-sensitized solar cells (DSC) have been studied. Ag doped ZnO powder was produced by the self-sustaining combustion process using ultrasonic spraying heating method. Luminescence wavelength region of the ZnO by Ag doping was shifted to longer wavelength. Tn the case of the Ag doped ZnO powder, broad luminescence spectrum centered on 600nm was observed. On the other hand, we compared PL data of RTA treated ZnO:Ag film at various temperatures because the front electrode of solar cell was in need of the sintering process. In XRD and PL data for RTA treated film at the 500$^{\circ}C$ showed good property. And, it was found that the grain size wasn't growing but only optical property was changed. According to the result of XRD, PL, absorption, emission spectrum and DV-X${\alpha}$ used in theoretical calculation, it is considered to be possible to use Ag doped ZnO as quantum dot material for improving DSC efficiency.

• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.289-292
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• 2015

The etching processes of glass in aqueous hydrofluoric acid (HF) solutions were used to improve the current density of solar cell. In this study, the textured glass substrate has been etched by solution and the $TiO_2$ thin films have been prepared on this textured glass. After the $TiO_2$ film deposition the surface has been etched by HF under different concentration and the etched $TiO_2$ thin films had a longer electron lifetime and higher haze ratio as well as light scattering, resulting in 1.7 times increment of dye-sensitized solar-cell(DSSC) efficiency. Increases in the surface root-mean-square roughness of glass substrates from 80 nm to 1774 nm enhanced haze ratio in above 300 nm wavelength. In particular, haze ratio of etched $TiO_2$ films on textured glass showed gradually increasing tendency at 550 nm wavelength by increasing of HF concentration up to 10M, suggesting a formation of crater with various sizes on its surface.