• Korean Journal of Chemical Engineering
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• 제35권12호
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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.

• 한국전기전자재료학회논문지
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• 제36권1호
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• pp.16-22
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• 2023

In a solar cell, degradation refers to the decrease in performance parameters caused by defects originated due to various causes. During the fabrication process of solar cells, degradation is generally related to the processes such as passivation or firing. There exist sources of many types of degradation; however, the exact cause of Light and elevated Temperature Induced Degradation (LeTID) is yet to be determined. It is reported that the degradation and the regeneration occur due to the recombination of hydrogen and an arbitrary substance. In this paper, we report the deposition of Al₂O₃ and SiN_X on silicon wafers used in the Passivated Emitter and Rear Contact (PERC) solar structure and its degradation pattern. A higher degradation rate was observed in the sample with single layer of Al₂O₃ only, which indicates that the degradation is affected by the presence or the absence of a passivation thin film. In order to alleviate the degradation, optimization of different steps should be carried out in consideration of degradation in the solar cell fabrication process.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1262-1263
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• 2008

Recently film-typed dye sensitized solar cell(DSC) attracts much attention with increasing applications for its flexibility and transparency. The ZnO:Al thin film, which serves mainly as transparent conducting electrode, Aluminium-doped zinc oxide(ZnO:Al) thin film has emerged as one of the most promising transparent conducting films since it is inexpensive, mechanically stable, and highly resistant to deoxidation. In this paper ZnO:Al thin film was deposited on the polyethylene terephthalate(PET) substrate by the capacitively coupled r. f. magnetron sputtering method. The effects of gas pressure and r. f. discharge power on the morphological, electrical and optical properties of ZnO:Al thin film were studied. Especially the variation in substrate thickness after sputtering and surface morphology of the substrate were investigated and clarified. The results showed that the film deposited on the PET substrate at r. f. discharge power of 180 W showed the minimum resistivity of about $1.5{\times}10^{-3}{\Omega}-cm$ and a transmittance of about 93%.

• 한국표면공학회지
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• 제48권1호
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• pp.23-26
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• 2015

What causes the transformation of a solar cell is the behavior difference of thermal expansion occurred between the substrate and the layer of semiconductor used in the solar cell. Therefore, the substrate has to possess a behavior of thermal expansion that is similar with that of semiconductor layer. This study employed electroforming to manufacture Fe-Ni alloy materials of different compositions. To verify the result from a finite element analysis, a two-dimensional Mo substrate was calculated and its verification experiment was conducted. The absolute values from the finite element analysis of Mo/substrate structure and its verification experiment showed a difference. However, the size of residual stress of individual substrate compositions had a similar tendency. Two-dimensional CIGS/Mo/$SiO_2$/substrate was modeled. Looking into the residual stress of CIGS layer occurred while the temperature declined from $550^{\circ}C$ to room temperature, the smallest residual stress was found with the use of Fe-52 wt%Ni substrate material.

• Transactions on Electrical and Electronic Materials
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• 제13권1호
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• pp.35-38
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• 2012

In this study, we have attempted to characterize the photovoltaic effect in real-time measurement of photoinduced current in a poly-Si-based solar cell using photoconductive atomic force microscopy (PC-AFM). However, the high contact resistance that originates from the metal-semiconductor Schottky contact disturbs the current flow and makes it difficult to measure the photoinduced current. To solve this problem, a thin metallic film has been coated on the surface of the device, which successfully decreases the contact resistance. In the PC-AFM analysis, we used a metal-coated conducting cantilever tip as the top electrode of the solar cell and light from a halogen lamp was irradiated on the PC-AFM scanning region. As the light intensity becomes stronger, the current value increases up to $200{\mu}A$ at 80 W, as more electrons and hole carriers are generated because of the photovoltaic effect. The ratio of the conducting area at different conditions was calculated, and it showed a behavior similar to that generated by a photoinduced current. On analyzing the PC-AFM measurement results, we have verified the correlation between the light intensity and photoinduced current of the poly-Si-based solar cell in nanometer scale.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.208-208
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• 2010

Indium zinc tin oxide (IZTO) thin films were studied as a possible alternative to indium tin oxide (ITO) films for providing low-cost transparent conducting oxide (TCO) for thin film photovoltaic devices. IZTO films were deposited onto glass substrates at room temperature. A dc/rf magnetron co-sputtering system equipped with a ceramic target of the same composition was used to deposit TCO films. Earlier studies showed that the resistivity value of $In_{0.6}Zn_{0.2}Sn_{0.2}O_{1.5}$ (IZTO20) films could be lowered to approximately $6{\times}10^{-4}ohm{\cdot}cm$ without sacrificing optical transparency and still maintaining amorphous structure through the optimization of process variables. The growth rate was kept at about 8 nm/min while the oxygen-to-argon pressure ratio varied from 0% to 7.5%. As-deposited films were always amorphous and showed strong oxygen pressure dependence of electrical resistivity and electron concentration values. Influence of forming gas anneal (FGA) at medium temperatures was also studied and proven effective in improving electrical properties. In this study, the chemical composition of the targets and the films varied around the $In_{0.6}Zn_{0.2}Sn_{0.2}O_{1.5}$ (IZTO20). It was the main objective of this paper to investigate how off-stoichiometry affected TCO characteristics including electrical resistivity and optical transmission. In addition to the composition effect, we have also studied how film properties changed with processing variables. IZTO thin films have shown their potential as a possible alternative to ITO thin films, in such way that they could be adopted in some applications where currently ITO and IZO thin films are being used. Our experimental results are compared to those obtained for commercial ITO thin films from solar cell application view point.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.808-810
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• 2005

Inexpensive large area arrays of thin film transistors (TFTs) on flexible substrates will enable many new display products that cannot be cost effectively manufactured by conventional means. This paper presents a new approach for low cost manufacturing of electronic devices using roll-to-roll (R2R) processes exclusively. It was developed in partnership by Hewlett Packard Laboratories and Iowa Thin Film Technologies (ITFT), a solar cell manufacturer. The approach combines ITFT's unique processes for vacuum deposition and etching of semiconductors, dielectrics and metals on continuous plastic webs with a method HP has invented for the patterning and aligning the multiple layers of a TFT with sub-micron accuracy and feature size.

• 한국수소및신에너지학회논문집
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• 제16권2호
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• pp.130-135
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• 2005

Cadmium selenide is one of the group IIb-VI compounds, which is the promising semiconductor material due to its wide range of technological applications in optoelectronic devices such as photoelectrochemical cells, solid state solar cells, thin film photoconductors etc. CdSe has optical band gap of 1.7-1.8eV and proper conduction band edge for water splitting. CdSe films are coated with small thickness(20-50nm) nanocrystalline $TiO_2$ film by electrodeposition or chemical bath deposition methods and PEC properties of CdSe and CdSe/$TiO_2$ sandwich structure are studied. The photoactivity of CdSe and CdSe/$TiO_2$ films deposited on titanium substrate is studied in aqueous electrolyte of 1M NaOH solution. Photocurrent and photovoltage obtained were of the order of 2-4 mA/$cm^2$ and 0.5V, respectively, under the intensity of illumination of 100 mW/$cm^2$.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.138-138
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• 2009

Recently, thin-film solar cells of Cu(In,Ga)$Se_2$(CIGS) have reached a high level of performance, which has resulted in a 19.9%-efficient device. These conventional devices were typically fabricated using chemical bath deposited CdS buffer layer between the CIGS absorber layer and ZnO window layer. However, the short wavelength response of CIGS solar cell is limited by narrow CdS band gap of about 2.42 eV. Taking into consideration the environmental aspect, the toxic Cd element should be replaced by a different material. It is why during last decades many efforts have been provided to achieve high efficiency Cd-free CIGS solar cells. In order to alternate CdS buffer layer, ZnS buffer layer is grown by using chemical bath deposition(CBD) technique. The thickness and chemical composition of ZnS buffer layer can be conveniently by varying the CBD processing parameters. The processing parameters were optimized to match band gap of ZnS films to the solar spectrum and exclude the creation of morphology defects. Optimized ZnS buffer layer showed higher optical transmittance than conventional thick-CdS buffer layer at the short wavelength below ~520 nm. Then, chemically deposited ZnS buffer layer was applied to CIGS solar cell as a alternative for the standard CdS/CIGS device configuration. This CIGS solar cells were characterized by current-voltage and quantum efficiency measurement.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.424-424
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• 2008

Dye-sensitized Solar Cell (DSC) is a new type of solar cell by using photocatalytic properties of $TiO_2$. The electric potential distribution in DSCs has played a major role in the operation of such cells. Models based on a built-in electric field which sets the upper limit for the open circuit voltage(Voc) and/or the possibility of a Schottky barrier at the interface between the mesoporous wide band gap semiconductor and the transparent conducting substrate have been presented. $TiO_2$ thin films were deposited on the FTO substrate by Nd:YAG Pulsed Laser Deposition(PLD) at room temperature and post-deposition annealing at $500^{\circ}C$ in flowing $O_2$ atmosphere for 1 hour. The structural properties of $TiO_2$ thin films have investigated by X-ray diffraction(XRD) and atomic force microscope(AFM). Thickness of $TiO_2$ thin films were controlled deference deposition time and measurement by scanning electron microscope(SEM). Then we manufactured a DSC unit cells and I-V and efficiency were tested using solar simulator.