Sungjin Jo
Kyungpook National University
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Publication
Featured researches published by Sungjin Jo.
Scientific Reports | 2015
Sanggil Nam; Myungkwan Song; Dong-Ho Kim; Byung Jin Cho; Hye Moon Lee; Jung-Dae Kwon; Sung-Gyu Park; Kee-Seok Nam; Yongsoo Jeong; Se-Hun Kwon; Sung-Ho Jin; Jae-Wook Kang; Sungjin Jo; Chang Su Kim
Transparent electrodes have been widely used in electronic devices such as solar cells, displays, and touch screens. Highly flexible transparent electrodes are especially desired for the development of next generation flexible electronic devices. Although indium tin oxide (ITO) is the most commonly used material for the fabrication of transparent electrodes, its brittleness and growing cost limit its utility for flexible electronic devices. Therefore, the need for new transparent conductive materials with superior mechanical properties is clear and urgent. Ag nanowire (AgNW) has been attracting increasing attention because of its effective combination of electrical and optical properties. However, it still suffers from several drawbacks, including large surface roughness, instability against oxidation and moisture, and poor adhesion to substrates. These issues need to be addressed before wide spread use of metallic NW as transparent electrodes can be realized. In this study, we demonstrated the fabrication of a flexible transparent electrode with superior mechanical, electrical and optical properties by embedding a AgNW film into a transparent polymer matrix. This technique can produce electrodes with an ultrasmooth and extremely deformable transparent electrode that have sheet resistance and transmittance comparable to those of an ITO electrode.
Applied Physics Letters | 2013
Myungkwan Song; Jae-Wook Kang; Dong-Ho Kim; Jung-Dae Kwon; Sung-Gyu Park; Sanggil Nam; Sungjin Jo; Seung Yoon Ryu; Chang Su Kim
Organic solar cells with inverted structures can greatly improve photovoltaic stability. This paper reports a method to lower the work function of indium tin oxide (ITO) in inverted organic solar cells by modification with ultrathin 3-aminopropyltriethoxysilane (APTES) monolayers. The device studies showed that the resulting photovoltaic efficiencies were significantly increased from 0.64% to 4.83% with the use of the APTES monolayer, which could be attributed to the dramatic enhancement in the open-circuit voltage and fill factor. The effective electron selectivity in the case of the APTES-modified ITO could be attributed to the reduction of the work function of ITO as a result of the electron-donating nature of the amine groups in the APTES monolayer. The power conversion efficiency of the unencapsulated inverted organic solar cells with APTES-modified ITO remained above 80% of their original values even after storage in air for thirty days. Our results provide a promising approach to improve the performance of highly efficient and air-stable inverted organic solar cells.
Scientific Reports | 2017
Bonhee Ha; Sungjin Jo
To improve the electrical properties of silver nanowire (Ag NW) transparent conductive electrodes (TCEs), the density of Ag NW networks should be increased, to increase the number of percolation paths. However, because of the inverse relationship between optical transmittance and electrical resistivity, the optical properties of Ag NW TCEs deteriorate with increasing density of the Ag NW network. In this study, a hybrid Ag NW electrode composed of randomly oriented and grid-patterned Ag NW networks is demonstrated. The hybrid Ag NW electrodes exhibit significantly improved sheet resistances and slightly decreased transmittances compared to randomly oriented Ag NW networks. Hybrid Ag NW TCEs show excellent mechanical flexibilities and durabilities in bending tests with a 5 mm radius of curvature. Moreover, flexible transparent film heaters (TFHs) based on the hybrid Ag NW electrodes show elevated maximum temperatures relative to TFHs based on randomly oriented Ag NW electrodes, when operated at the same input voltages.
Scientific Reports | 2017
Jiyoon Nam; Bowook Seo; Young-Joo Lee; Dongho Kim; Sungjin Jo
Increasing interests in stretchable electronic devices have resulted in vigorous research activities, most of which are focused on structural configurations. Diverse structural configurations are available for stretchability, including stiff-island, serpentine, and buckled structures. With easily deformable shapes and simple fabrication processes, buckled structures have the potential to realize stretchability. However, conventional buckled structures exhibit stretchability only in a single-axis direction. In the present study, a new type of cross-buckled structure, which can overcome the limitations of conventional buckled structures is developed. The stretchable thin film solar cells with the cross-buckled structure showed stable mechanical and electrical characteristics under both stretching and compressing conditions. The cross-buckled structure for stretchable electronic devices is expected to broaden the fields of wearable electronics, stretchable displays, and biocompatible applications.
AIP Advances | 2017
Yuhong Cheon; Jiyoon Nam; Chang Su Kim; Sungjin Jo
This paper introduces a simple hydrazine treatment method to reduce the yellowing of silver nanowire transparent conductive electrodes. To investigate the effects of hydrazine treatment on the yellowing of silver nanowire electrodes, the optical and electrical properties of silver nanowire electrodes were analyzed before and after hydrazine treatment. The optimal hydrazine treatment conditions were investigated by varying the concentration and thickness of hydrazine; the effect of hydrazine treatment on the long-term stability of silver nanowires was also analyzed.
Journal of Nanomaterials | 2016
Jiyoon Nam; Youngjoo Lee; Chang Su Kim; Hogyoung Kim; Dongho Kim; Sungjin Jo
We demonstrate a compact amorphous silicon a-Si solar module to be used as high-voltage power supply. In comparison with the organic solar module, the main advantages of the a-Si solar module are its compatibility with photolithography techniques and relatively high power conversion efficiency. The open circuit voltage of a-Si solar cells can be easily controlled by serially interconnecting a-Si solar cells. Moreover, the a-Si solar module can be easily patterned by photolithography in any desired shapes with high areal densities. Using the photolithographic technique, we fabricate a compact a-Si solar module with noticeable photovoltaic characteristics as compared with the reported values for high-voltage power supplies.
Advanced Energy Materials | 2014
Wonjung Choi; Chang Zoo Kim; Chang Su Kim; Wooseok Heo; Taiha Joo; Seung Yoon Ryu; Hogyoung Kim; Hongjoon Kim; Ho Kwan Kang; Sungjin Jo
Advanced Energy Materials | 2016
Jiyoon Nam; Youngjoo Lee; Wonjung Choi; Chang Su Kim; Hogyoung Kim; Jongbok Kim; Dong-Ho Kim; Sungjin Jo
Current Applied Physics | 2012
Dae Sung You; Chang Su Kim; Yong Jin Kang; Kyounga Lim; Sunghoon Jung; Do-Geun Kim; Jong-Kuk Kim; Sungjin Jo; Joo Hyun Kim; Jae-Wook Kang
ECS Solid State Letters | 2015
Nami Kang; Wonjung Choi; Hogyoung Kim; Chang Su Kim; Sungjin Jo