• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.381-381
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• 2011

In this study, a TiO2 colloidal sol was synthesized by sol-gel process, which was used as a "glue" agent to enhance interconnection of TiO2 particles in low temperature process for plastic dye sensitized solar cell. The crystalline phase of this TiO2 glue is pure anatase with average particles size of 5 nm, which was characterized by powder X-ray diffraction and high revolution-TEM. The viscous alcoholic paste without any organic binder was prepared from the mixture of commercial P25 powder and glue. Paste composition and sintering process parameters were optimized for high photovoltaic performance based on low temperature process. The electrochemical impedance spectroscopy and photocurrent-photovoltage transient spectroscopy were also employed to investigate the mechanism of electron transport in this binder free TiO2 film system.

• Journal of The Korean Astronomical Society
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• v.38 no.4
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• pp.445-462
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• 2005

In a companion paper, we have presented so-called Spatio-Spectral Maximum Entropy Method (SSMEM) particularly designed for Fourier-Transform imaging over a wide spectral range. The SSMEM allows simultaneous acquisition of both spectral and spatial information and we consider it most suitable for imaging spectroscopy of solar microwave emission. In this paper, we run the SSMEM for a realistic model of solar microwave radiation and a model array resembling the Owens Valley Solar Array in order to identify and resolve possible issues in the application of the SSMEM to solar microwave imaging spectroscopy. We mainly concern ourselves with issues as to how the frequency dependent noise in the data and frequency-dependent variations of source size and background flux will affect the result of imaging spectroscopy under the SSMEM. We also test the capability of the SSMEM against other conventional techniques, CLEAN and MEM.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.461-466
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• 2011

In this study, the fluorine doped $TiO_2$ was prepared as a photoelectrode in order to improve the efficiency of dye-sensitized solar cells and estimated the electrochemical characterizations. The energy conversion efficiency of the prepared dye-sensitized solar cells using fluorine doped $TiO_2$ was calculated from a current-voltage curve. The efficiency of prepared dye-sensitized solar cells was improved by about maximum three times by F-doping on $TiO_2$. It was suggested that the efficiency of dye-sensitized solar cells was improved by hybrid semiconductors of $TiO_2/TiOF_2$ in photoelectrode based on reduced $TiOF_2$ energy level via fluorine doping. It can be confirmed that the electron transport was faster but the electron recombination was slower by doping fluorine on $TiO_2$ in photoelectrode through intensity-modulated photocurrent spectroscopy and intensity-modulated photovoltage spectroscopy analysis.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.1
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• pp.71-75
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• 2022

Graphene oxide was stirred with a ZnCl₂:NaCl electrolyte and electrochemically coated by cyclic voltammetry to simplify the electron transpfer layer film forming process for organic solar cells and to fabricate an organic solar cell having it. The device structure is FTO/ZnO:graphene/P3HT:PCBM/PEDOT:PSS/Ag. Morphology and chemical properties of ETL were confirmed by scanning electron microscopy(SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. As a result of XPS measurement, ZnO metal oxide and carbon bonding were simultaneously confirmed, and ZnO and graphene peaks were confirmed by Raman spectroscopy. The electrical characteristics of the manufactured solar cell were specified with a solar simulator, and the ETL device coated twice at a rate of 0.05 V/s showed the highest photoelectric conversion efficiency of 1.94%.

• Journal of Integrative Natural Science
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• v.9 no.4
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• pp.275-280
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• 2016

Intensity modulated photovoltage spectroscopy (IMVS) analysis of organic solar cells (OSCs) with a bulk-heterojunction (BHJ) film composed of P3HT and $PC_{61}BM$ was performed. The dynamic response of charge recombination by the post-annealing approach in $P3HT/PC_{61}BM$ BHJ solar cells characterized by IMVS demonstrated that post-annealing reduced the recombination of electron carriers in the device. The recombination times of $P3HT/PC_{61}BM$ BHJ solar cells post-annealed at room temperature, 80, 120, and $140^{\circ}C$ were 0.009, 0.020, 0.024, and 0.030 ms, respectively, at a short-circuit current of 0.18 mA. The results indicated that the IMVS analysis can be effectively used as powerful.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.72-72
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• 2011

Surface science is intrinsically related to the performance of solar cells. In solar cells the generation and collection of charge carriers determines their efficiency. Effective transport of charge carriers across interfaces and minimization of their recombination at surfaces and interfaces is of utmost importance. Thus, the chemistry at the surfaces and interfaces of these devices must be determined, and related to their performance. In this talk we will discuss the role of two important interfaces, First, the role of surface passivation is very important in limiting the rate of carrier of recombination. Here we will combine x-ray photoelectron spectroscopy of the surface of a Si device with electrical measurements to ascertain what factors determine the quality of a solar cell passivation. In addition, the quality of the heterojunction interface in a ZnSe/CdTe solar cell affects the output voltage of this device. X-ray photoelectron spectroscopy gives some insight into the composition of the interface, while ultraviolet photoemission yields the relative energy of the two materials' valence bands at the junction, which controls the open circuit voltage of the solar cell. The relative energies of ZnSe and CdTe at the interface is directly affected by the material quality of the interface through processing.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1204-1207
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• 2009

We investigated the device performance of bulk heterojunction solar cells depending on the active layer thickness. For the systematic comparison, the polymer solar cells comprising RR-P3HT:PCBM (1:0.8 (wt%:wt%)) blend films with different thickness were characterized by impedance spectroscopy, and J-V measurement in dark and solar simulated illumination. The device with 120 nm thickness of active layer exhibited maximum power conversion efficiency of 3.5 % under AM 1.5 100mW/$cm^2$ illumination condition.

• Korean Journal of Materials Research
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• v.29 no.11
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• pp.697-702
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• 2019

In this study, using a wet chemical process, we evaluate the effectiveness of different solution concentrations in removing layers from a solar cell, which is necessary for recovery of high-purity silicon. A 4-step wet etching process is applied to a 6-inch back surface field(BSF) solar cell. The metal electrode is removed in the first and second steps of the process, and the anti-reflection coating(ARC) is removed in the third step. In the fourth step, high purity silicon is recovered by simultaneously removing the emitter and the BSF layer from the solar cell. It is confirmed by inductively coupled plasma mass spectroscopy(ICP-MS) and secondary ion mass spectroscopy(SIMS) analyses that the effectiveness of layer removal increases with increasing chemical concentrations. The purity of silicon recovered through the process, using the optimal concentration for each process, is analyzed using inductively coupled plasma atomic emission spectroscopy(ICP-AES). In addition, the silicon wafer is recovered through optimum etching conditions for silicon recovery, and the solar cell is remanufactured using this recovered silicon wafer. The efficiency of the remanufactured solar cell is very similar to that of a commercial wafer-based solar cell, and sufficient for use in the PV industry.

• Analytical Science and Technology
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• v.5 no.1
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• pp.135-142
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• 1992

Indium tin oxide(ITO) films coated on the window glass selectively transmit the solar energy and infrared. We call this system passive solar collectors. Selectively absorbing properties of sol gel dip coated ITO films were characterized by UV-VIS-NIR spectroscopy. The effects of heat treating temperature, time, atmosphere, substrate and barrier layers are concerned. Indium tin oxide films heat-treated at $500^{\circ}C$ in a reducing atmosphere show intrinsic properties. Efficiency of solar energy transmittance was enhanced by coating of $SiO_2-ZrO_2$ as an alkali ion barrier layer. Energy was saved by the double layers of $SiO_2-ZrO_2$ and ITO since solar energy is transmitted and heat generated inside(${\lambda}$ > 2700nm) is reflected.

• Journal of Electrochemical Science and Technology
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• v.7 no.3
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• pp.218-227
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• 2016

The light harvesting efficiency is counted as an important factor in the power conversion efficiency of DSSCs. There are two measures to improve this parameter, including enhancing the dye-loading capacity and increasing the light trapping in the photoanode structure. In this paper, these tasks are addressed by introducing a macro-porous silicon (PSi) substrate as photoanode. The effects of the novel photoanode structure on the DSSC performance have been investigated by using energy dispersive X-ray spectroscopy, photocurrent-voltage, UV-visible spectroscopy, reflectance spectroscopy, and electrochemical impedance spectroscopy measurements. The results indicated that bigger porosity percentage of the PSi structure improved the both anti-reflective/light-trapping and dye-loading capacity properties. PSi based DSSCs own higher power conversion efficiency due to its remarkable higher photocurrent, open circuit voltage, and fill factor. Percent porosity of 64%, PSi(III), resulted in nearly 50 percent increment in power conversion efficiency compared with conventional DSSC. This paper showed that PSi can be a good candidate for the improvement of light harvesting efficiency in DSSCs. Furthermore, this study can be considered a valuable reference for more investigations in the design of multifunctional devices which will profit from integrated on-chip solar power.