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Publication
Featured researches published by Jeong O. Lee.
Energy and Environmental Science | 2016
Jin Young Oh; Ji Hoon Lee; Sun Woong Han; Soo Sang Chae; Eun Jin Bae; Young Hun Kang; Won Jin Choi; Song Yun Cho; Jeong O. Lee; Hong Koo Baik; Tae Il Lee
To utilize human heat energy as a permanent power source, we demonstrate, for the first time, an intrinsically highly foldable and stretchable thermoelectric generator that is based upon chemically exfoliated 1T-transition metal dichalcogenide (TMDC) nanosheets (NSs) for self-powered wearable electronics. The power factors of WS2 (n-type) and NbSe2 (p-type) NS films were evaluated to be 5–7 μ K−2 m−1 and 26–34 μW K−2 m−1, respectively, near room temperature. With these films, parallel-connected thermoelectric generators that were fabricated were able to constantly produce up to 38 nW of output power at Δ60 K. The thermoelectric device stably sustained its performance, even after 100 bending cycles and after 100 stretching cycles (50% strain). By direct observation, we found that the film is highly stretched by partial tearing and folding but still maintains an electrical percolation pathway. The morphology then is quickly recovered by a plug-in contact between the torn parts as the external strain is released. Finally, we demonstrate the electric power generation from a prototype wearable thermoelectric generator that was woven into a wristband fitted on a real human body.
Scientific Reports | 2015
Won Jin Choi; Yoon Jang Chung; Yun Ho Kim; Jeongho Han; Young Kook Lee; Ki Jeong Kong; Hyunju Chang; Young Kuk Lee; Byoung Gak Kim; Jeong O. Lee
Controlling the orientations of nanomaterials on arbitrary substrates is crucial for the development of practical applications based on such materials. The aligned epitaxial growth of single-walled carbon nanotubes (SWNTs) on specific crystallographic planes in single crystalline sapphire or quartz has been demonstrated; however, these substrates are unsuitable for large scale electronic device applications and tend to be quite expensive. Here, we report a scalable method based on graphoepitaxy for the aligned growth of SWNTs on conventional SiO2/Si substrates. The “scratches” generated by polishing were found to feature altered atomic organizations that are similar to the atomic alignments found in vicinal crystalline substrates. The linear and circular scratch lines could promote the oriented growth of SWNTs through the chemical interactions between the C atoms in SWNT and the Si adatoms in the scratches. The method presented has the potential to be used to prepare complex geometrical patterns of SWNTs by ‘drawing circuits using SWNTs without the need for state-of-the-art equipment or complicated lithographic processes.
Nanotechnology | 2009
Eun Kyoung Jeon; Hyunsang Seo; Chi Won Ahn; Han-Kyu Seong; Heon-Jin Choi; Ju Jin Kim; Ki Jeong Kong; Gyoung-Ho Buh; Hyunju Chang; Jeong O. Lee
We have fabricated Si(1-x)Ge(x) alloy nanowire devices with Ni and Ni/Au electrodes. The electrical transport characteristics of the alloy nanowires depended strongly on the annealing temperature and contact metals. Ni/Au-contacted devices annealed at 400 degrees C showed p-type transistor behavior as well as a resistance switching effect, while no switching was observed from Ni-contacted alloy nanowire devices. To identify the origin of such a hysteretic resistance switching effect, we constructed nanowire devices on a 40 nm Si(3)N(4) membrane. Transmission electron microscopy analysis combined with electrical transport measurements revealed that devices contacted with Ni/Au, and thereby showing resistance switching, have Au atoms right next to the alloy nanowire.
Archive | 2008
Byoung-Kye Kim; Hyo-Suk Kim; Hye-Mi So; Noejung Park; Suklyun Hong; Ju-Jin Kim; Jeong O. Lee
Through recent publications, as reviewed in this article, we have determined the effects of contact barrier change on the electrical transport properties of carbon nanotube field-effect transistors. To analyze the Fermi level alignment and the Schottky barrier at the contact, we used the first-principles electronic structure calculations of different types of metal electrodes with various bonding configurations. In parallel, we have used various experimental techniques to engineer the contact barrier: decorations of metal nanoparticles, the self-assembled monolayers of molecules, and protein nanoparticles. We investigated the changes in the electron transport properties of the nanotube transistors in relation to the adjustment of the contact barrier. Overall reviews of these studies are presented here, and a few potential applications are also suggested.
Physical Review B | 2005
Byoung Kye Kim; Ju Jin Kim; Jeong O. Lee; Ki Jeong Kong; Han Jong Seo; Cheol Jin Lee
Archive | 2007
Hye Mi So; Jeong O. Lee; Yong Hwan Kim; Ki Hoon Won; Hyun Ju Chang; Beyong Hwan Ryu; Ki Jeong Kong; Young Min Choi
Archive | 2003
Hyun Ju Chang; Young Min Choi; Ki Jeong Kong; Jeong O. Lee; Jin Woo Lee; Byung Whan Ryu
Archive | 2014
Won Jin Choi; 최원진; Jeong O. Lee; 이정오; Young Kuk Lee; 이영국; Yoon Jang Chung; 정윤장; Se Rin Park; 박세린
Journal of Nanoscience and Nanotechnology | 2008
Eun Kyoung Jeon; Hyo Suk Kim; Byoung Kye Kim; Ju Jin Kim; Jeong O. Lee; Cheol Jin Lee
Archive | 2013
Won Jin Choi; 최원진; Jeong O. Lee; 이정오; Young Kuk Lee; 이영국; Yoon Jang Chung; 정윤장; Se Rin Park; 박세린