• Journal of the Korean Solar Energy Society
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• v.35 no.4
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• pp.57-66
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• 2015

BIPV system not only produces electricity at building, but also acts as a material for building envelope. Thus, it can increase the economical efficiency of PV system by saving the cost for building materials. Bifacial solar cell can convert solar energy to electrical energy from both sides of the cell. In addition, it is designed as 3 busbar layout which is the same with ordinary mono-facial solar cells. Therefore, many of the module manufacturers can easily use the bifacial solar cells without changing their manufacturing equipments. Moreover, bifacial PV system has much potential in building application by utilizing glass-to-glass structure of PV module. However, the electrical generation of the bifacial PV module depends on the characteristics of the building surface which faces the module, as well as outdoor environment. Therefore, in order to apply the bifacial PV module to building envelope as BIPV system, its power generation characteristics are carefully evaluated. For this purpose this study focused on the electrical performance of the bifacial BIPV system through the comparative outdoor experiments. As a result, the power generation performance of the bifacial BIPV system was improved by up to 21% compared to that of the monofacial BIPV system. Therefore, it is claimed that the bifacial BIPV system can replace the conventional BIPV system to improve the PV power generation in buildings.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.594-594
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• 2012

Al doped ZnO (AZO) thin films were deposited on textured glass substrate by magnetron sputtering method. Also, AZO films on textured glass were etched by hydrochloric acid (HCl). Average thickness of etched AZO films are 90 nm. We observed morphology of AZO film by AFM with various etchant concentration and etching time. Etched AZO films have low resistivity and high haze. The surface RMS roughness of AZO film was increased from 53.8 nm to 84.5 nm. The haze ratio was also enhanced in above 700 nm of wavelength due to light trapping effect was increased by rough AZO surface. The etched AZO films on textured glass are applicable to fabricate solar cell.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.426.1-426.1
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• 2016

We report high work function Aluminum doped zinc oxide (AZO) films as insertion layer as a function of O2 flow rate between transparent conducting oxides (TCO) and hydrogenated amorphous silicon oxide (a-SiOx:H) layer to improve open circuit voltage (Voc) and fill factor (FF) for high efficiency thin film solar cell. However, amorphous silicon (a-Si:H) solar cells exhibit poor fill factors due to a Schottky barrier like impedance at the interface between a-SiOx:H windows and TCO. The impedance is caused by an increasing mismatch between the work function of TCO and that of p-type a-SiOx:H. In this study, we report on the silicon thin film solar cell by using as insertion layer of O2 reactive AZO films between TCO and p-type a-SiOx:H. Significant efficiency enhancement was demonstrated by using high work-function layers (4.95 eV at O2=2 sccm) for engineering the work function at the key interfaces to raise FF as well as Voc. Therefore, we can be obtained the conversion efficiency of 7 % at 13mA/cm2 of the current density (Jsc) and 63.35 % of FF.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.444-445
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• 2009

The metallic contact system of silicon solar cell must have several properties, such as low contact resistance, easy application and good adhesion. Ni is shown to be a suitable barrier to Cu diffusion as well as desirable contact metal to silicon. Nickel monosilicide(NiSi) has been suggested as a suitable silicide due to its lower resistivity, lower sintering temperature and lower layer stress than $TiSi_2$. Copper and Silver can be plated by electro & light-induced plating method. Light-induced plating makes use the photovoltaic effect of solar cell to deposit the metal on the front contact. The cell is immersed into the electrolytic plating bath and irradiated at the front side by light source, which leads to a current density in the front side grid. Electroless plated Ni/ Electro&light-induced plated Cu/ Light-induced plated Ag contact solar cells result in an energy conversion efficiency of 16.446 % on $0.2\sim0.6\;{\Omega}{\cdot}cm$, $20\;\times\;20\;mm^2$, CZ(Czochralski) wafer.

• Electrical & Electronic Materials
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• v.10 no.9
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• pp.930-937
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• 1997

Polycrystalline CdTe thin films have been studied for photovoltaic application because of their high absorption coefficient and optimal band energy(1.45 eV) for solar energy conversion. In this study CdTe thin films were deposited on CdS(chemical bath deposition)/ITO(indium tin oxide) substrate by rf-magnetron sputtering under various conditions. Structural optical and electrical properties are investigated with XRD UV-Visible spectrophotometer SEM and solar simulator respectively. The fabricated CdTe/CdS solar cell exhibited open circuit voltage( $V_{oc}$ ) of 610 mV short circuit current density( $J_{sc}$ ) of 17.2 mA/c $m^2$and conversion efficiency of about 5% at optimal sputtering conditions.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2909-2912
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• 2010

Hydrogenated microcrystalline silicon (${\mu}c$-Si:H) thin film for solar cells is prepared by plasma-enhanced chemical vapor deposition and physical properties of the ${\mu}c$-Si:H p-layer has been investigated. With respect to stable efficiency, this film is expected to surpass the performance of conventional amorphous silicon based solar cells and very soon be a close competitor to other thin film photovoltaic materials. Silicon in various structural forms has a direct effect on the efficiency of solar cell devices with different electron mobility and photon conversion. A Raman microscope is adopted to study the degree of crystallinity of Si film by analyzing the integrated intensity peaks at 480, 510 and $520\;cm^{-1}$, which corresponds to the amorphous phase (a-Si:H), microcrystalline (${\mu}c$-Si:H) and large crystals (c-Si), respectively. The crystal volume fraction is calculated from the ratio of the crystalline and the amorphous phase. The results are compared with high-resolution transmission electron microscopy (HR-TEM) for the determination of crystallinity factor. Optical properties such as refractive index, extinction coefficient, and band gap are studied with reflectance spectra.

• Transactions on Electrical and Electronic Materials
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• v.9 no.1
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• pp.28-32
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• 2008

Hydrogenated microcrystalline silicon(${\mu}c$-Si:H) films were prepared using inductively coupled plasma chemical vapor deposition(ICP-CVD) method, electrical and optical properties of these films were studied as a function of silane concentration. And then, effect of $PH_3\;and\;B_2H_6$ addition on their electrical properties was also investigated for solar cell application. Characterization of these films from X-ray diffraction revealed that the conductive film exists in microcrystalline phase embedded in an amorphous network. At $PH_3/SiH_4$ gas ratio of $0.9{\times}10^{-3}$, dark conductivity has a maximum value of ${\sim}18.5S/cm$ and optical bandgap also a maximum value of ${\sim}2.39eV$. Boron-doped ${\mu}c$-Si:H films, satisfied with p-layer of solar cell, could be obtained at ${\sim}10^{-2}\;of\;B_2H_6/SiH_4$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.05a
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• pp.33-34
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• 1988

Recent developments in characterization techniques for solar cells are reviewed. First, general rules of material selection for solar cells such as $CuInSe_2$ and amorphous silicon of photovoltaic application are studied. Secondly, a method to obtain correct cell efficiency measurements under AM1 condition is introduced. Thirdly, various characterization techniques for solar cells are discussed. A special emphasis is given to up-scaling and computer control of the characterizations in the following systems; cell I-V characteristics for cell efficiency and other cell parameters, spectral response for quantum efficiency, surface photovoltage for diffusion length of minority carriers, and photothermal deflection for density of states in energy gaps.

• Transactions on Electrical and Electronic Materials
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• v.4 no.5
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• pp.10-14
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• 2003

A low-cost, large area, random, maskless texturing scheme independent of crystal orientation is expected to have significant impact on terrestrial photovoltaic technology. We investigated silicon surface microstructures formed by reactive ion etching (R IE) in Multi-Hollow cathode system. Desirable texturing effect has been achieved when radio-frequency (rf) power of about 20 Watt per one hollow cathode glow is applied for our RF Multi -Hollow cathode system. The black silicon etched surface shows almost zero reflectance in the visible region as well as in near IR region. The etched silicon surface is covered by columnar microstructures with diameters from 50 to 100 nm and depth of about 500 nm. We have successfully achieved 11.7 % efficiency of mono-crystalline silicon solar cell and 10.2 % for multi-crystalline silicon solar cell.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2436-2440
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• 2009

In this work, TCO-less dye-sensitized solar cells (DSCs) using Ti-mesh layer is fabricated for high-efficient low-cost solar cell application. The Ti-mesh metal can replace TCO in the photo-electrode part of DSCs, thus the cell structure is composed of a glass/dye sensitized TiO2 particle/ Ti-mesh layer/electrolyte/Pt sputtered counter electrode/ glass. The Ti-mesh electrode with high conductivity can collect electrons from the $TiO_2$ layer and allows the ionic diffusion of $I^-/I_3^-$ through the mesh hole. Thin Ti-mesh ($\sim40{\mu}m$ in thickness) electrode material is processed using rapid prototype method. The efficiency of prepared TCO-less DSCs sample is about 1.45 % ((ff: 0.5, Voc: 0.52V, Jsc: 5.55 $mA/cm^2$).