• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.3
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• pp.198-203
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• 2013

Dye-sensitized solar cells (DSSCs) based on titanium dioxide ($TiO_2$) have been extensively studied because of their promising low-cost alternatives to conventional semiconductor based solar cells. DSSCs consist of molecular dye at the interface between a liquid electrolyte and a mesoporous wide-bandgap semiconductor oxide. Most efforts for high conversion efficiencies have focused on dye and liquid electrolytes. However, interface engineering between dye and electrode is also important to reduce recombination and improve efficiency. In this work, for interface engineering, we deposited semiconducting ferroelectric $BiFeO_3$ with bandgap of 2.8 eV on $TiO_2$ nanoparticles and nanotubes. Photovoltaic properties of DSSCs were characterized as a function of thickness of $BiFeO_3$. We showed that ferroelectric $BiFeO_3$-coated $TiO_2$ electrodes enable to increase overall efficiency of DSSCs, which was associated with efficient electron transport due to internal electric field originating from electric polarization. It was suggested that engineering the dye-$TiO_2$ interface using ferroelectric materials as inorganic modifiers can be key parameter for enhanced photovoltaic performance of the cell.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.26-32
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• 2021

The photovoltaic properties and microstructure changes were observed while perovskite solar cells (PSCs) with a fabricated carbon electrode were formed using the following annealing processes: hot-plate, oven, and rapid thermal annealing (RTA). Perovskite solar cells with a glass/FTO/compact TiO2/meso TiO2/meso ZrO2/carbon structure were prepared. The photovoltaic properties and microstructure changes in the PSCs were analyzed using a solar simulator, optical microscopy, and field emission scanning electron microscopy. An analysis of the photovoltaic properties revealed outstanding properties when RTA was applied to the cells. Microstructure analysis showed that perovskite was formed locally on the carbon electrode surface when hot-plate and oven annealing were applied. On the other hand, PSC with RTA showed a flat surface without extra perovskite agglomeration. Denser perovskite formed on the porous carbon electrode layer with RTA showed superior photovoltaic properties. These results suggest that the RTA process might be appropriate for the massive production of carbon electrode PSCs considering the processing time.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.833-834
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• 2011

• Current Photovoltaic Research
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• v.6 no.1
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• pp.21-26
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• 2018

Beside several advantages, the PV power generation as a clean energy source, is still below the supply level due to high power generation cost. Therefore, the interest in fabricating low-cost thin film solar cells is increasing continuously. $Cu_2O$, a low cost photovoltaic material, has a wide direct band gap of ~2.1 eV has along with the high theoretical energy conversion efficiency of about 20%. On the other hand, it has other benefits such as earth-abundance, low cost, non-toxic, high carrier mobility ($100cm^2/Vs$). In spite of these various advantages, the efficiency of $Cu_2O$ based solar cells is still significantly lower than the theoretical limit as reported in several literatures. One of the reasons behind the low efficiency of $Cu_2O$ solar cells can be the formation of CuO layer due to atmospheric surface oxidation of $Cu_2O$ absorber layer. In this work, atomic layer deposition method was used to remove the CuO layer that formed on $Cu_2O$ surface. First, $Cu_2O$ absorber layer was deposited by electrodeposition. On top of it buffer (ZnO) and TCO (AZO) layers were deposited by atomic layer deposition and rf-magnetron sputtering respectively. We fabricated the cells with a change in the deposition temperature of buffer layer ranging between $80^{\circ}C$ to $140^{\circ}C$. Finally, we compared the performance of fabricated solar cells, and studied the influence of buffer layer deposition temperature on $Cu_2O$ based solar cells by J-V and XPS measurements.

• Current Photovoltaic Research
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• v.8 no.3
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• pp.94-101
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• 2020

This study was trying to focus on achieving high efficiency of multi junction solar cell with thin film silicon solar cells. The proposed thin film Si-Ge/c-Si tandem junction solar cell concept with a combination of low-cost thin-film silicon solar cell technology and high-efficiency c-Si cells in a monolithically stacked configuration. The tandem junction solar cells using amorphous silicon germanium (a-SiGe:H) as an absorption layer of upper sub-cell were simulated through ASA (Advanced Semiconductor Analysis) simulator for acquiring the optimum structure. Graded Ge composition - effect of E_g profiling and inserted buffer layer between absorption layer and doped layer showed the improved current density (J_sc) and conversion efficiency (η). 13.11% conversion efficiency of the tandem junction solar cell was observed, which is a result of showing the possibility of thin film Si-Ge/c-Si tandem junction solar cell.

• Current Photovoltaic Research
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• v.4 no.2
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• pp.48-53
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• 2016

We report the effect of physical load on the stability of organic solar cells under physical loads. The active layers in organic solar cells were fabricated with bulk heterojunction films (BHJ) films of poly (3-hexylthiophene) and phenyl-$C_{61}$-butyric methyl ester. The loading time was varied up to 60 s by keeping the physical load constant. Results showed that the open circuit voltage was not influenced by the physical load but other solar cell parameters were sensitive to the loading time. The fill factor was very slightly increased at 15 s, while short circuit current density was well kept for 30 s. The power conversion efficiency was reasonably maintained for 45 s but became significantly decreased by the continuous loading for 60 s.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.63-63
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• 2011

In this tutorial session, the field of organic photovoltaic (OPV) cells based on small molecular weight materials will be presented. The previously reported studies on the fabrication, structure, and property of the cells as well as the molecular materials are included. Especially, the factors hampering further enhancement in the power conversion efficiency of the cells such as exciton recombination, light absorption and interfacial morphology between electron donor and acceptor layer will be discussed in detail. The recent progress in our group will also be presented. It includes typical materials and cell fabrication techniques we used as well as the studies on improving the light absorption in the electron donor layer and reducing the extinction of excitons formed by introducing the nanostructured interface between organic layers.

• Nuclear Engineering and Technology
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• v.5 no.1
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• pp.13-19
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• 1973

The photovoltaic and the electronvoltaic cells have been obtained by forming Sb-implanted n- on p-type and In-implanted p- on n-type silicon p-n junctions Such shallow implantations into silicon wafers due to each dopant were done by the VDH-Implanter. The two types of the silicon p-n junction for these cells have shown special features on their various characteristics to be fitted for the direct energy conversions. The results of the comparative study on both of these cells are described in this article.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.37-49
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• 2008

Recent rapid progress in the photovoltaic industry has seriously been retarded by limited supply of polysilicon used as the feedstock for silicon wafer-based solar cells. It is thus believed that development of a competitive process for preparing polysilicon with the quality required for solar cells can greatly enhance the competitiveness and extent of the photovoltaic application. Technologies currently available for preparing the silicon feedstock are reviewed with the recent fluidized bed silicon deposition process being discussed in more details in terms of key technical barriers.

• Current Photovoltaic Research
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• v.6 no.3
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• pp.74-80
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• 2018

Recently, perovskite solar cells have shown tremendous improvement in power conversion efficiencies. Moreover, they have potential in semitransparent solar cell applications due to their high absorption coefficients. In order to fabricate semitransparent perovskite solar cells with good performance, it is essential to consider the suitability of transparent electrode materials in various aspects, such as transparency, conductivity and fabrication process. In this review, candidate materials for transparent electrodes in perovskite solar cells including carbon-based nanomaterials, conductive polymers and metallic nanostructures are discussed.