• Current Photovoltaic Research
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• v.5 no.1
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• pp.1-8
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• 2017

Two different fluorine-doped tin oxide (FTO)-coated glass substrates were investigated to find better suitability for CdTe solar cells. Substrate A consisted of FTO (300 nm)/$SiO_2$ (24 nm)/intrinsic $SnO_2$ (30 nm)/borosilicate glass (2.2 mm), and substrate B consisted of FTO (700 nm)/intrinsic $SnO_2$ (30nm)/borosilicate glass (1.8 mm). The overall thickness of the FTO/glass substrates was about 2.5 mm. The total light transmittance of substrate B was much higher than that of substrate A throughout the whole spectral region, even though the thickness of the FTO in substrate B was twice larger than that of the FTO in the substrate A. The short-circuit current greatly increased in substrate B and the external quantum efficiency (EQE) increased over the whole wavelength range. This study shows that the diffuse optical transmittance played a key role in the large EQE value in the blue wavelength region, and the direct transmittance played a key role in the large EQE value in the red wavelength region. The higher transmittance is due to the rough surface generated by the thicker FTO on glass. The conversion efficiency of the CdTe solar cell increased from 12.4 to 15.1% in combination of rough FTO substrate and Cu solution back contact.

• Journal of Sensor Science and Technology
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• v.21 no.6
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• pp.395-401
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• 2012

The bond strength of three types of $TiO_2$ coatings onto fluorine-doped $SnO_2$ (FTO) glass was investigated with the aid of a tape test according to ASTM D 3359-95. Transmittance was then measured using an UV-vis spectrophotometer in the wavelength range of 300 nm to 800 nm to evaluate the extent of adhesion of $TiO_2$ nanorods/nanoparticles on FTO glass. A sharp interface between the coating layer and the substrate was observed for single $TiO_2$ coating ($TiO_2$ nanorods/FTO glass), which may be detrimental to the bonding strength. In multicoating sample ($TiO_2$ nanorod/$TiO_2$ nanoparticle/$TiO_2$ nanoparticle/FTO glass), the tape test was not performed due to severe peeling-off prior to the test. On the other hand, the dual coating sample ($TiO_2$ nanorod/$TiO_2$ nanoparticle/FTO glass) showed minimum variation of transmittance (4%) after the test, suggesting that the topcoat adheres well with the FTO substrate due to the presence of the $TiO_2$ nanoparticle buffer layer. The use of a $TiO_2$ nanorod electrode layer with good adhesion may be attributed to the excellent dye sensitized solar cell performance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.208-212
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• 2013

Dye-sensitized solar cells (DSCs) have taken much attention due to their low cost and easy fabrication method compare to silicon solar cells. But research on cost effective DSC is prerequisite for commercialization. Fluorine doped tin oxide (FTO) which have been commonly used for electrode substrate as electron collector occupied most percentage of manufacturing cost. Therefore we studied FTO-less DSC using sputtered Ti deposited glass as photoelectrode instead of FTO to reduce manufacturing cost. Ti films sputtered on the glass for different time, 5 to 20 minutes with decreasing sheet resistance as deposition time increases. A light source illuminated to counter electrode in order to overcome opaque Ti films. The efficiency of DSC (Ti20) made Ti sputtered glass for 20 min as photoelectrode was 5.87%. There are no significant difference with conventional cell despite lower manufacturing cost.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.1
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• pp.37-43
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• 2012

We were studied that AZO conductive thin film can substitute for FTO electrode in dye sensitized solar cell. Three types of AZO films were deposited on soda-lime glass(AZO/glass, AZO/AZO/glass, textured AZO/AZO/glass) using RF magnetron sputtering process and investigated their properties of electrical, optical, and photoelectric conversion rate. The textured AZO/AZO/glass has the lowest resistivity of $3.079{\times}10^{-4}\;{\Omega}cm$ among other films. And the optical transmittance rate was better than both non textured AZO/AZO/glass and FTO/glass in the visible region. After manufacturing dye solar cells using the three types of AZO films, the textured AZO/AZO/glass showed the highest photoelectric conversion rate of 3.68% among AZO samples. But the transformation rate was slightly lower than FTO cells (4.52%). However, the conductive film of textured AZO/AZO/glass can be applicable to use an electrode in solar cells as cost-effective products.

• Korean Journal of Metals and Materials
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• v.50 no.8
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• pp.557-562
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• 2012

Self-organized ruthenium (Ru) dots were fabricated by $400^{\circ}C$ RTA (rapid thermal annealing) and ALD (atomic layer deposition). The dots were produced under the $400^{\circ}C$ RTA conditions for 10, 30 and 60 seconds on all Si(100)/200 nm-SiO2, glass, and glass/fluorine-doped tin oxide (FTO) substrates. Electrical sheet resistance, and surface microstructure were examined using a 4-point probe and FE-SEM (field emission scanning electron microscopy). Ru dots were observed when a 30 nm-Ru layer on a Si(100)/200 nm-SiO2 substrate was annealed for 10, 30 and 60 seconds, whereas the dots were only observed on a glass substrate when a 50 nm-Ru layer was annealed on glass. For a glass/FTO substrate, RTA <30 seconds was needed for 30 nm Ru thick films. Those dots can increase the effective surface area for silicon and glass substrates by up to 5-44%, and by 300% for the FTO substrate with a < $20^{\circ}$ wetting angle.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.836-839
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• 2011

염료감응형 태양전지의 상대전극으로 MWCNT(multi-walled carbon nanotube)의 농도 (0.01~0.06g)를 달리하여 FTO(fluorine-doped tin oxide) glass에 분산시켜 상대전극을 만들었다. 그리고 glass/FTO/$TiO_2$/Dye(N719)/electrolyte(C6DMII,GSCN)/MWCNT/FTO/glass 구조를 가진 0.45$cm^2$급 DSSC(dye-sensitized solar cells) 소자를 만들었다. 소자의 미세구조, 분산정도, 광특성은 각각 광학현미경, SEM, source measure unit (Keithley model 2400) 장비를 이용하여 확인하였다. MWCNT 농도 증가와 FTO의 거친 표면형상에 따라 비선형적으로 MWCNT 분산면적이 증가하였고, MWCNT 농도 0.06g일 때 FTO 표면에 전체적으로 MWCNT가 완전히 분산됨을 확인하였다. 소자의 광변환 효율은 MWCNT 분산면적에 비례하는 효율을 보였고, MWCNT 분산농도인 0.06g 일 때 4.49%의 광변환 효율을 얻을 수 있었다.

• Journal of the Korean Ceramic Society
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• v.52 no.2
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• pp.103-107
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• 2015

The effective glass frit composition used to absorb laser energy and to seal commercial dye-sensitized solar cell panel substrates has been previously developed using $V_2O_5-TeO_2$-based glass with 10 wt% ${\beta}$-eucryptite as a CTE controlling filler. The optimum sealing conditions are provided using a 3 mm beam, a laser power of 40 watt, a scan speed of 300 mm/s, and 200 irradiation cycles. In this study, the feasibility of the developed glass frit is investigated in terms of the sealing strength and chemical durability against the commercial iodide/triiodide electrolyte solution and fluorine-doped tin oxide (FTO) electrode in order to increase the solar cell lifetime. The sealing strength of the laser-sealed $V_2O_5-TeO_2$-based glass frit is $20.5{\pm}1.7MPa$, which is higher than those of thermally sealed glass frit and other reported glass frit. Furthermore, the developed glass frit is chemically stable against electrolyte solutions. The glass frit constituents are not leached out from the glass after soaking in the electrolyte solution for up to three months. During the laser sealing, the glass frit does not react with the FTO electrode; thus, the resistivity of the FTO electrode beneath the laser-sealed area remains the same.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.98-103
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• 2011

We prepared a counter electrode by electroplating Ni as underlayer and Pt as plating layer on the FTO glass to increase the efficiency of dye-sensitized solar cell (DSSC). We found an excellent adhesion between Ni underlayer and FTO glass when Ni underlayer was electroplated at $10mA/cm^2$ for 2 min on FTO glass. We observed Ni and Pt metal diffraction peaks by XRD analysis when Ni underlayer was electroplated at $10mA/cm^2$ for 2 min, and Pt layer was electroplated at $5mA/cm^2$ for 1 min on the Ni underlayer. Photovoltaic performance and impedance analysis of DSSCs fabricated with this counter electrode shows the highest efficiency of 5.6% and the lowest resistance of 75 ohm.

• Transactions on Electrical and Electronic Materials
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• v.14 no.2
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• pp.86-89
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• 2013

Dye-sensitized solar cells have a FTO/$TiO_2$/Dye/Electrode/Pt counter electrode structure, yet more than a 10% electron loss occurs at each interface. A passivating layer between the $TiO_2$/FTO glass interface can prevent this loss of electrons. In theory, ZnO has excellent electron collecting capabilities and a 3.4 eV band gap, which suppresses electron mobility. FTO glass was coated with ZnO thin films by RF-magnetron sputtering; each film was deposited under different $O_2$:Ar ratios and RF-gun power. The optical transmittance of the ZnO thin film depends on the thickness and morphology of ZnO. The conversion efficiency was measured with the maximum value of 5.22% at an Ar:$O_2$ ratio of 1:1 and RF-gun power of 80 W, due to effective prevention of the electron recombination into electrolytes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.76-79
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• 2014

We report Zinc oxide (ZnO) nanorods synthesis and electrochemical luminescence (ECL) cell fabrication. The ECL cell was fabricated using the electrode of ZnO nanorods and Ru(II) complex ($Ru(bpy)_3{^{2+}}$) as a luminescence materials. The fabricated ECL cell is composed of F-doped $SnO_2$ (FTO) glass/ Ru(II)/ZnO nanorods/FTO glass. The highest intensity of the emitting light was obtained at the wavelength of ~620 nm which corresponds to dark-orange color. At a bias voltage of 3V, the measured ECL efficiencies were 5 $cd/m^2$ for cell without ZnO nanorod, 145 $cd/m^2$ for ZnO nanorods-$5{\mu}m$, 208 $cd/m^2$ for ZnO nanorods-$8{\mu}m$ and 275 $cd/m^2$ for ZnO nanorods-$10{\mu}m$, respectively. At a bias voltage of 3.5V, the use of ZnO nanorods increases ECL intensities by about 3 times compared to the typical ECL cell without the use of ZnO nanorods.