• Current Photovoltaic Research
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• v.9 no.1
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• pp.6-10
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• 2021

The mesh mask screen, which is generally used for screen printing metallization of silicon solar cell, requires high squeegee pressure and low printing speed. These requirements are acting as a limiting factor in production yield in photovoltaic industries. In order to improve the productivity, a metal mask, which has high durability and high printing speed, has been researched. In this paper, the characteristics of each solar cell, in which electrodes were formed by using a metal mask and a mesh mask, were analyzed through recombination current density. In particular, the metal-induced recombination current density (Jom) representing the recombination of the emitter-metal interface was calculated using the shading method, and the resulting efficiency and open-circuit voltage were analyzed through the diode equation. As a result of analyzing the proportion of the metal-induced recombination current density to the total emitter recombination current density, it was analyzed that the reduction of the metal-induced recombination current density through the metal mask is an important factor in reducing the total recombination current density of the solar cell.

• Current Photovoltaic Research
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• v.9 no.4
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• pp.128-132
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• 2021

Advances in screen printing technology have been led to development of high efficiency silicon solar cells. As a post PERx structure, an n-type wafer-based rear side TOPCon structure has been actively researched for further open-circuit voltage (Voc) improvement. In the case of the metal contact of the TOPCon structure, the poly-Si thickness is very important because the passivation of the substrate will be degraded when the metal paste penetrates until substrate. However, the thin poly-Si layer has advantages in terms of current density due to reduction of parasitic absorption. Therefore, poly-Si thickness and firing temperature must be considered to optimize the metal contact of the TOPCon structure. In this paper, we varied poly-Si thickness and firing peak temperature to evaluate metal induced recombination (Jom) and contact resistivity. Jom was evaluated by using PL imaging technique which does not require both side metal contact. As a results, we realized that the SiN_x deposition conditions can affect the metal contact of the TOPCon structure.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.311-324
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• 2018

Herein,the Neodymium ion ($Nd^{3+}$) doped CoAl-LDH have been successfully prepared via co-precipitation method and was used as a precursor of Nd-doped CoAl-mixed metal oxides (MMO). The photocatalytic activity of doped LDH and MMO was investigated in the degradation of an azo dye, C.I. Acid Red 14, under visible light irradiation. DRS and PL analysis demonstrated decreasing in the band gap energy and recombination of photo-induced charge carriers of Nd-doped LDH and MMO compared with the pristine CoAL-LDH. Due to significant difference in photocatalytic performance. A power law empirical kinetic model was obtained for predicting the photocatalytic degradation efficiency.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.68-69
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• 2011

The process of charge transfer at the interface between two semiconductors or between a metal and a semiconductor plays an important role in many areas of technology. The optimization of such devices requires a good theoretical description of the interfaces involved. This, in turn, has motivated detailed mechanistic studies of interfacial charge-transfer reactions at metal/organic, organic/organic, and organic/inorganic semiconductor heterojunctions. Charge recombination of photo-induced electron with redox species such as oxidized dyes or triiodide or cationic HTM (hole transporting materials) at the heterogeneous interface of $TiO_2$ is one of main loss factors in liquid junction DSSCs or solid-state DSSCs, respectively. Among the attempts to prevent recombination reactions such as insulating thin layer and lithium ions-doped hole transport materials and introduction of co-adsorbents, although co-adsorbents retard the recombination reactions as hydrophobic energy barriers, little attention has been focused on the anchoring processes. Molecular engineering of heterogeneous interfaces by employing several co-adsorbents with different properties altered the surface properties of $TiO_2$ electrodes, resulting to the improved power conversion efficiency and long-term stability of the DSSCs. In this talk, advantages of the coadsorbent-assisted sensitization of N719 in preparation of DSSCs will be discussed.

• Progress in Medical Physics
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• v.9 no.1
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• pp.11-21
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• 1998

Circular metal electrodes were vacuum-deposited with chromium on the both sides of Teflon-FEP and PET film characteristic of electret and the physical properties of the two polymers were observed during an irradiation by gamma-ray from $\^$60/Co. With the onset of irradiation of output 25.0 cGy/min the induced current increased rapidly for 2 sec, reached a maximum, and subsequently decreased. A steady-state induced current was reached about in 60 second. The dielectric constant and conductivity of Teflon-FEP were changed from 2.15 to 18.0 and from l${\times}$l0$\^$-17/ to 1.57${\times}$10$\^$-13/ $\Omega$-$\^$-1/cm$\^$-1/, respectively. For PET the dielectric constant was changed from 3 to 18.3 and the conductivity from 10$\^$-17/ to 1.65${\times}$10$\^$-13/ $\Omega$-$\^$-1/cm$\^$-1/. The increase of the radiation-induced steady state current I$\^$c/, permittivity $\varepsilon$ and conductivity $\sigma$ with output(4.0 cGy/min, 8.5 cGy/min, 15.6 cGy/min, 19.3 cGy/min) was observed. A series of independent measurements were also performed to evaluate reproducibility and revealed less than 1% deviation in a day and 3% deviation in a long term. Charge and current showed the dependence on the interval between measurements, the smaller the interval was, the bigger the difference between initial reading and next reading was. At least in 20 minutes of next reading reached an initial value. It may indicate that the polymers were exhibiting an electret state for a while. These results can be explained by the internal polarization associated with the production of electron-hole pairs by secondary electrons, the change of conductivity and the equilibrium due to recombination etc. Heating to the sample made the reading value increase in a short time, it may be interpreted that the internal polarization was released due to heating and it contributed the number of charge carriers to increase when the samples was again irradiated. The linearity and reproducibility of the samples with the applied voltage and absorbed dose and a large amount of charge measured per unit volume compared with the other chambers give the feasibility of a radiation detector and make it possible to reduce the volume of a detector.