|Speaker||Prof. Hyojung Kim (Pusan National University)|
|Date||Thu. 23 May. 2019|
|Venue||#331, Asan Hall, College of Science|
Molecular Engineering for Organic Electronics and Synchrotron X-rays
We present molecular engineering for Organic Photovoltaics (OPVs) in conjugated polymer systems with fs-laser, molecular templating growth (MTG) with graphene, and solvent engineering. In case of poly(3-hexylthiophene)(P3HT) films, face-on favorable nanostructure formed by fs-laser irradiation. The dipole moment of P3HT could align along the electric field of irradiated laser, which induced face-on stacking of P3HT polymers in the films. The vertical charge current increased in the fs-laser irradiated region due the enhancement of face-on stacking. [1-4]
For the face-on favorable stacking of P3HT polymers, we adopted dry transferred graphene as a templating layer. In contrast to conventional PMMA-assisted wet transferred wet transferred graphene, dry transferred graphene is found in the current work to be quite suitable for use in the roll-to-roll process due to its lack of PMMA residue, whose removal would require high-temperature annealing. When we produce a P3HT film with a thickness of 30 nm, the face-on populations of P3HT were prominent on both the dry and wet transferred graphene layers. As the film thickness is increased to 50 nm, the face-on population decreased on the wet transferred graphene surface, but retained high levels on the dry transferred graphene.
Finally, we tried to control crystallinity of P3HT layer by solvent to form ideal BHJ (bulk heterojunction) structure in Sequential (Sq) process for OPVs. In the Sq process, a bi-layered structure is formed by the sequential deposition of the acceptor and donor layers, and the final BHJ nanostructure is formed at the interface between the layers by carrying out an additional procedure involving thermal annealing and swelling. We investigated the inter-diffusion of acceptor material at the interface in different crystalline structured layers as a function of gradual thermal annealing. We found that the P3HT films made using a low-boiling-point solvent had fewer crystalline regions and lots of amorphous regions, which enabled fullerene molecules to readily penetrate into P3HT layer within a short period of time.
We took Grazing-Incidence Wide-Angle X-ray Scattering (GIWAXS) and NEXAFS (Near Edge X-ray Absorption Fine structure) based on synchrotron x-rays for detail structural studies.
 S. Chae, K. H. Jo, S. W. Lee, H.-S. Geum, H. J. Kim, J. Choi, H. H. Lee, Macromol. Chem. Phys. 217, 537-543 (2016).
 S. Chae, A. Yi, C. M. Park, W. S. Chang, H. H. Lee, J. Choi, H. J. Kim, ACS Appl. Mater. Interfaces 9, 24422-24427 (2017).
 S. Chae, K. Jo, S. J. Won, A. Yi, J. Choi, H. H. Lee, J. H. Kim, H. J. Kim, Adv. Mater. Interfaces 4, 1701099 (2017).
 S. Chae, A. Yi, H. H. Lee, J. Choi, H. J. Kim, Journal of Materials Chemistry C (2018, in printing).
|Notice||Spring semester 2019 Seminar Schedule||-||-|
|65||Fall semester 2018 Seminar Schedule||-||-|
|64||Fall semester 2016 Seminar Schedule||-||-|
|63||Spring semester 2017 Seminar Schedule||-||-|
|62||[Thu. 27 Apr. 2017] Seminar was canceled!||-||-|
|61||Fall semester 2017 Seminar Schedule||-||-|
|60||[Wed. 5 July. 2017] Seminar is canceled!||-||-|
|59||7th Jilin-Korea-Waseda Alliance Annual Symposium||-||August 17 ~ 19, 2017|
|58||[Fri. 13 Oct. 2017] Dr. J. Nathan Hohman/The Molecular Foundry, Lawrence Berkeley National Laboratory, California, USA||Dr. J. Nathan Hohman||Fri. 13 Oct. 2017|
|57||[Fri. 16 Jun. 2017] Prof. Martin Thuo/Department of Materials Science and Engineering, Iowa State University, USA||Prof. Martin Thuo||Fri. 16 Jun. 2017|
|56||[Fri. 17 Mar. 2017] 9th RINS Symposium||-||Fri. 17 Mar. 2017|
|55||[Fri. 30 Oct. 2017] Prof. Igor Rodin/Department of Chemistry, Moscow State University, Moscow, Russia||Prof. Igor Rodin||Fri. 30 Oct. 201|
|54||[Fri. 17 Jun. 2016] Prof. Jianwei Sun/Remote Control in Brønsted Acid Catalysis: New Strategies for the Synthesis of Chiral Building Blocks and Medium Rings||Prof. Jianwei Sun||Friday 17 June 2016|
|53||[January 24, 2018] Electro-Optic Organic THz Wave Sources||Prof. O-Pil Kwon(Ajou University)||January 24, 2018 (Wednesday)|
|52||[March 20, 2019] Challenges in molecular dynamics simulations of unfolded proteins and protein-DNA complexes||Dr. Jejoong Yoo||March 20, 2019|
|51||[March 27, 2019] Hyperpolarization Researches with NV center, 129Xe and Parahydrogen||Prof. Keunhong Jeong||March 27, 2019|
|50||[Mon. 16 Oct. 2017] Prof. Kirk S. Schanze/Department of Chemistry, University of Texas at San Antonio, Texas, USA||Prof. Kirk S. Schanze||Mon. 16 Oct. 2017|
|49||[Mon. 9 Jan. 2017] Prof. Sungwook Woo/Wyss Institute for Biologically Inspired Engineering, Harvard University, USA||Prof. Sungwook Woo||Mon. 9 Jan. 2017|
|48||[Mon. 13 Oct. 2016] Prof. Amir H. Hoveyda/Multicomponent Catalytic Synthesis of Organoboron Compounds for Scalable Natural Product Synthesis||Prof. Amir H. Hoveyda||Monday 13 October 2016|
|47||[November 14, 2017] Zero-Point Energy, Fluctuations, and Dissipation : A (Mostly) Quantum-Optical Perspective||Prof. Milonni, Peter||November 14, 2017|
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