• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.257-257
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• 2009

This paper explores a control of recombination velocity for optimization the crystalline solar cell. Using PC1D simulator, the efficiency of crystalline solar cell was measured to be about 17%. The results show that the lower the front recombination velocity is, the more efficiency of crystalline solar cell improves. The work which presented here has profound implications for studies of crystalline solar cell and someday may help solve the problem of optimization for the crystalline solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제27권1호
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• pp.45-49
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• 2014

We have fabricated white organic light-emitting diodes (OLEDs) using several thicknesses of electron-transport layer. The multi-emission layer structure doped with red and blue phosphorescent guest emitters was used for achieving white emission. 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) was used as an electron-transport layer. The thickness of BCP layer was varied to be 20, 55, and 120 nm. The current efficiency, emission and recombination characteristics of multi-layer white OLEDs were investigated. The BCP layer thickness variation results in the shift of emission spectrum due to the recombination zone shift. As the BCP layer thickness increases, the recombination zone shifts toward the electron-transport layer/emission-layer interface. The white OLED with a 55 nm thick BCP layer exhibited a maximum current efficiency of 40.9 cd/A.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.74-74
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• 2011

Polymer solar cells utilize bulk heterojunction (BHJ) type photo-active layer in which the electron donating polymer and electron accepting C60 derivatives are mixed together. In the BHJ system the electron donating polymer and electron accepting C60 derivatives are blended. The blended system causes charge recombination at the interface between the BHJ active layer and electrode. To reduce the charge recombination at the interface, it is needed to use an interlayer that can selectively transfer electrons or holes. We have developed solution processable wide band gap inorganic interfacial layers for polymer solar cells. The effect of interlayers on the performance of polymer solar cell was investigated for various types of conjugated polymers. We have found that inorganic interfacial layers enhanced the solar cell efficiency through the reduction of charge recombination at the interface between active layer and electrode. Furthermore, the stability of the polymer solar cell using the interlayer was significantly improved. The efficiency of 6.5% was obtained from the PTB7:PCBM70 based solar cells utilizing $TiO_2$nanoparticles as an interlayers.

• Current Photovoltaic Research
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• 제9권1호
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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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.256-256
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• 2009

This paper presents a proper condition to achieve above 17 % conversion efficiency using PC1D simulator. Crystalline silicon wafer with thickness of $240{\mu}m$ was used as a starting material. Various efficiency influencing parameters such as rear surface recombination velocity and minority carrier diffusion length in the base region, front surface recombination velocity, junction depth and doping concentration in the Emitter layer. Among the investigated variables, we learn that 2nd doping concentration as a key factor to achieve conversion efficiency higher than 17 %.

• Transactions on Electrical and Electronic Materials
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• 제17권1호
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• pp.37-40
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• 2016

Performance enhancement of organic light-emitting diodes (OLEDs) is investigated in a device structure of ITO/TPD/Alq₃/LiF/Al and ITO/TPD/Alq₃/BCP/LiF/Al. Here, bathocuproine (BCP) is used as an electron-transport layer. Current density-voltage-luminance characteristics of the OLEDs show that the performance of the device is better with BCP layer than without BCP layer. The current density, luminance, luminous efficiency, and external-quantum efficiency are improved by approximately 22%, 50%, 2%, and 18%, respectively. Since the BCP layer lowers the electron energy barrier, electron transport is facilitated and the movement of hole is blocked as the applied voltage increases. This results in an increased recombination rate of holes and electrons.

• Journal of Animal Reproduction and Biotechnology
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• 제38권3호
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• pp.99-108
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• 2023

Background: Efficient gene editing technology is needed for successful knock-in. Homologous recombination (HR) is a major double-strand break repair pathway that can be utilized for accurately inserting foreign genes into the genome. HR occurs during the S/G2 phase, and the DNA mismatch repair (MMR) pathway is inextricably linked to HR to maintain HR fidelity. This study was conducted to investigate the effect of inhibiting MMR-related genes using CdCl₂, an MMR-related gene inhibitor, on HR efficiency in HC11 cells. Methods: The mRNA and protein expression levels of MMR-related genes (Msh2, Msh3, Msh6, Mlh1, Pms2), the HR-related gene Rad51, and the NHEJ-related gene DNA Ligase IV were assessed in HC11 cells treated with 10 μM of CdCl₂ for 48 hours. In addition, HC11 cells were transfected with a CRISPR/sgRNA expression vector and a knock-in vector targeting Exon3 of the mouse-beta casein locus, and treated with 10 μM cadmium for 48 hours. The knock-in efficiency was monitored through PCR. Results: The treatment of HC11 cells with a high-dose of CdCl₂ decreased the mRNA expression of the HR-related gene Rad51 in HC11 cells. In addition, the inhibition of MMR-related genes through CdCl₂ treatment did not lead to an increase in knock-in efficiency. Conclusions: The inhibition of MMR-related gene expression through high-dose CdCl₂ treatment reduces the expression of the HR-related gene Rad51, which is active during recombination. Therefore, it was determined that CdCl₂ is an inappropriate compound for improving HR efficiency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2011년도 춘계학술대회
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• pp.702-705
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• 2011

Poly-Si wafers with resistivity of 1 [${\Omega}$-cm[ and thickness of 50 [${\mu}m$] were used as a starting material. Various efficiency influencing parameters such as rear surface recombination velocity and minority carrier diffusion length in the base region, front surface recombination velocity, junction depth and doping concentration in the Emitter layer, BSF thickness and doping concentration were investigated. Optimized cell parameters were given as rear surface recombination of 1000 [cm/sec], minority carrier diffusion length in the base region 50 [${\mu}m$], front surface recombination velocity 100 [cm/sec], sheet resistivity of emitter layer 100 [${\Omega}/{\Box}$], BSF thickness 0.5 [${\mu}m$], doping concentration $5{\times}10^{19}\;cm^{-3}$. Among the investigated variables, we learn that a diffusion length of base layer acts as a key factor to achieve conversion efficiency higher than 19.8 %. Further details of simulation parameters and their effects to cell characteristics are discussed in this paper.

• Current Photovoltaic Research
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• 제8권1호
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• pp.6-11
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• 2020

The power conversion efficiency (PCE) of a two-terminal tandem solar cell depends upon the tunnel-recombination junction (TRJ) between the top and bottom sub-cells. An optimized TRJ in a tandem cell helps improve its open-circuit voltage (V_oc), short-circuit current density (J_sc), fill factor (FF), and efficiency (PCE). One of the parameters that affect the TRJ is the buffer layer thickness. Therefore, we investigated various TRJs by varying the thickness of the buffer or intermediate layer (TRJ-buffer) in between the highly doped p-type and n-type layers of the TRJ. The TRJ-buffer layer was p-type nc-Si:H, with a doping of 0.06%, an activation energy (E_a) of 43 meV, an optical gap (E_g) of 2.04 eV, and its thickness was varied from 0 nm to 125 nm. The tandem solar cells we investigated were a combination of a heterojunction with intrinsic thin layer (HIT) bottom sub-cell and an a-Si:H (amorphous silicon) top sub-cell. The initial cell efficiency without the TRJ buffer was 7.65% while with an optimized buffer layer, its efficiency improved to 11.74%, i.e., an improvement in efficiency by a factor of 1.53.

• Current Photovoltaic Research
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• 제6권2호
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• pp.43-48
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• 2018

The traditional silicon heterojunction solar cells consist of intrinsic amorphous silicon to prevent recombination of the silicon surface and doped amorphous silicon to transport the photo-generated electrons and holes to the electrode. Back contact solar cells with silicon heterojunction exhibit very high open-circuit voltages, but the complexity of the process due to form the emitter and base at the backside must be addressed. In order to solve this problem, the structure, manufacturing method, and new materials enabling the carrier selective contact (CSC) solar cell capable of achieving high efficiency without using a complicated structure have recently been actively developed. CSC solar cells minimize carrier recombination on metal contacts and effectively transfer charge. The CSC structure allows very low levels of recombination current (eg, Jo < 9fA/cm2), thereby achieves high open-circuit voltage and high efficiency. This paper summarizes the core technology of CSC solar cell, which has been spotlighted as the next generation technology, and is aiming to speed up the research and development in this field.