• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2430-2441
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• 2018

Selenium (Se)-rich binary Cu-Se and In-Se nanoparticles (NPs) were synthesized by a modified heat-up method at low temperature ($110^{\circ}C$) using the gum exudates from a cherry blossom tree. Coating of CISe absorber layer was carried out using Se-rich binary Cu-Se and In-Se NPs ink without the use of any external binder. Our results indicated that the gum used in the synthesis played beneficial roles such as reducing and capping agent. In addition, the gum also served as a natural binder in the coating of CISe absorber layer. The CISe absorber layer was integrated into the solar cell, which showed a power conversion efficiency (PCE) of 0.37%. The possible reasons for low PCE of the present solar cells and the steps needed for further improvement of PCE were discussed. Although the obtained PCE is low, the present strategy opens a new path for the fabrication of eco-friendly CISe NPs solar cell by a relatively chief non-vacuum method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.109-110
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• 2006

Nanocrystalline $TiO_2$ electrode were prepared by spray-printing in order to efficiency and improved fill factor. Different compositions of nanocrystalline $TiO_2$ pastes are described, based on $TiO_2$ powder made by ourselves. The produced by spray printing $TiO_2$ films were compare with the produced by squeeze printing $TiO_2$ films and was studied in the light of static I-V characteristics. The produced $TiO_2$ films are extensively characterized by means of spectroscopy(Ramon, XRD) and microscopy(FE-SEM).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.687-690
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• 2004

Fabrication and characterization of dye-sensitized TiO2 solar cells(DSSC) consisting of spray-coated TiO2 electrode, an electrolyte containing I-/I3- redox couple, and a Pt-coated counter electrode carried out, using mainly FE-SEM and solar simulator. Also, effect of rapid thermal annealing(RTA) temperatue on I-V curves of DSSCS consisting of approximately 10m thickness and $5{\times}5mm2$ active area. No significant difference in the apparent size of TiO2 clusters was observed with increasing RTA temperature. Also, an open circuit voltage(Voc) of approximately 0.70V and a short-circuit photocurrent(Jsc) of 8 to 12mA/cm2 were observed in the TiO2 solar cell. With increasing RTA temperature upto 550oC, photocurrent density of dye-sensitized solar cells was enhanced, leading to enhancing the efficiency of dye-sensitized solar cells having Pt-electroplated counter electrode.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.11
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• pp.971-975
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• 2013

In general, the solar photovoltaic power increases with higher solar insolation. However, the solar cell generation efficiency reduces because the solar cell surface is heated by solar insolation. According to advanced research, with a $1^{\circ}C$ increase in the solar cell surface temperature, the generation efficiency decreases by ~0.5%. To solve this problem, we conducted experiments in which we attempted to reduce the solar cell surface temperature using a water jet spray. In this study, we found the long-term experimental results of increases in solar power generation. The experimental results show a comparison of the site with and without cooling and cleaning equipment being installed. The results of the long-term experiments show that solar photovoltaic power generation is increased by at least 13% up to 19% with cooling and cleaning.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.3
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• pp.57-61
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• 2016

In order to protect the solar cells from the moisture and oxygen, we evaluated the electrical and optical properties for the $Cu(In,Ga)Se_2$ (CIGS) solar cells which were prepared by the spray coating method. Generally, the EVA (ethylene-vinyl acetate) films are laminated to protect the CIGS flexible solar cells, which results in a high cost process due to complicated devices. In this study, we tried to prepare the protection layers of the flexible CIGS flexible solar cells by using spray coating method instead of conventional laminating films in order to reduce the device weight as well as the process time. The CIGS solar cells with spray coating method showed an enhanced efficiency than the before treated sample (2.77% to 2.93%) and relatively proper water vapor transmission rate of the solar cells about 62.891 gm/[$m^2-day$].

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.4
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• pp.338-342
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• 2010

Carbon nanotubes (CNTs) have excellent electrical, chemical stability, mechanical and thermal properties. The MWCNT films were investigated as a transparent electrode for the solar cell, OLED, and field-emission display. MWCNT films were fabricated by air spray method, whose process is quite low-costed, using the multi-walled CNTs solution on glass substrates. Moreover, the most stable film was fabricated when the spraying time was 60 sec. The film that was sprayed with the MWCNT dispersion for 60 sec, has 300nm thick. And its electric resistivity, transmittance rate, mobility and carrier concentration are $6{\times}10^{-2}{\Omega}{\cdot}cm$, 50% at ${\lambda}=550mm$, $4.3{\times}10^{-2}cm^2/V{\cdot}s$ and $2.1{\times}10^{21}cm^{-3}$, respectively. Also, absorption energy of MWCNT films show from 3.9 eV to 4.6 eV. Furthermore, we can use MWCNT films fabricated by the spray method for the transparent electrode.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.84.2-84.2
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• 2010

PEMS (printed electro-mechanical system) is fabricated by means of various printing technologies. Passive and active components in 2D or 3D such as conducting lines, resistors, capacitors, inductors and TFT, which are printed with functional materials, can be classified in this category. And the issue of PEMS is applied to a R2R process in the manufacturing process. In many electro-devices, the vacuum process is used as the manufacturing process. However, the vacuum process has a problem: it is difficult to apply toa continuous process as a R2R printing process. In this paper, we propose an ESD (electro static deposition) printing process has been used to apply an organic solar cell of thin film forming. ESD is a method of liquid atomization by electrical forces, anelectrostatic atomizer sprays micro-drops from the solution injected into the capillary, with electrostatic force generated by electric potential of about tens of kV. ESD method is usable in the thin film coating process of organic materials and continuous process as a R2R manufacturing process. Therefore, we experiment the thin films forming of PEDOT:PSS layer and Active layer which consist of the P3HT:PCBM. The result of experiment, organic solar cell using ESD thin film coated method is occurred efficiency of about 1.4%. Also, the case of only used to ESD method in the active layer coating is occurred efficiency of about 1.86% as the applying a spin coating in the PEDOT:PSS layer. We can expect that ESD method is possible for continuous process to manufacture in the organic solar cell or OLED device.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.35.1-35.1
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• 2011

New photovoltaic (PV) materials and manufacturing approaches are needed for meeting the demand for lower-cost solar cells. The prototypal thin-film photovoltaic absorbers (CdTe and $Cu(In,Ga)Se_2$) can achieve solar conversion efficiencies of up to 20% and are now commercially available, but the presence of toxic (Cd,Se) and expensive elemental components (In, Te) is a real issue as the demand for photovoltaics rapidly increases. To overcome these limitations, there has been substantial interest in developing viable alternative materials, such as $Cu_2ZnSnS_4$ (CZTS) is an emerging solar absorber that is structurally similar to CIGS, but contains only earth abundant, non-toxic elements and has a near optimal direct band gap energy of 1.4~1.6 ev and a large absorption coefficient of ${\sim}10^4\;cm^{-1}$. The CZTS absorber layers are grown and investigated by various fabrication methods, such as thermal evaporation, e-beam evaporation with a post sulfurization, sputtering, non-vacuum sol-gel, pulsed laser, spray-pyrolysis method and electrodeposition technique. In the present work, we report an alternative method for large area deposition of CZTS thin films that is potentially high throughput and inexpensive when used to produce monolithically integrated solar panel modules. Specifically, we have developed an aqueous chemical approach based on chemical bath deposition (CBD) with a subsequent sulfurization heat treatment. Samples produced by our method were analyzed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, absorbance and photoluminescence. The results show that this inexpensive and relatively benign process produces thin films of CZTS exhibiting uniform composition, kesterite crystal structure, and good optical properties. A preliminary solar cell device was fabricated to demonstrate rectifying and photovoltaic behavior.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.632-637
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• 2015

Mesoporous $TiO_2$ granules were prepared by spray pyrolysis using nano-sized titania particles which were synthesized by a hydrothermal method, and they were evaluated as the photoanode of dye-sensitized solar cells. To enhance the cell efficiency, nanoparticles within granules were chemically interconnected by adding titanium ethoxide (TEOT) to colloidal spray solution. The resulting titania particles had anatase phase without forming rutile. $TiO_2$ granules obtained showed about 400 nm in size, the specific surface area of $74-77m^2/g$, and average pore size of 13-17 nm. The chemical modification of $TiO_2$ granules by adding TEOT initially to the colloidal spray solution was proved to be an effective way in terms of increasing both the light scattering within photoanode and the lifetimes of photo-excited electrons. Consequently, the light-harvesting efficiency of TEOT-modified granules (${\eta}=6.72%$) was enhanced about 14% higher than primitive nanoparticles.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.1
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• pp.6-11
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• 2019

Methylammonium lead halide ($MAPbX_3$, X = I, Br) thin films, used as the light absorber of perovskite solar cells, were prepared using the dual feed ultrasonic spray method. Going through a deposition at a substrate temperature of below $60^{\circ}C$ and then a final heat treatment at $75^{\circ}C$ for 5 minutes using dual feed ultrasonic spray method, $MAPbI_3$ single phase could be formed. Whereas undergoing a deposition at temperatures above $80^{\circ}C$, the spheroidal grains could be changed into rod-shaped fractal structures due to the decomposition of the perovskite phase. Furthermore, using the same method at a higher heat treatment temperature of $100^{\circ}C$, $MAPbI_{3-x}Br_x$ thin films could also be formed from $MAPbI_3$ and $MAPbIBr_2$ solution.