关于举行韩国Korea Advanced Institute of Science and Technology (KAIST) Prof. Jung-Yong Lee以及Bumjoon J. kim学术报告会的通知
报告题目：Utilizing metal nanostructures for optical and electrical gains in organic optoelectronic devices
报 告 人：Jung-Yong Lee, Graduate School of Energy, Environment, Water, and Sustainability (EEWS), Graphene Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701
时 间：2015年11月23日（星期一）上午9：30
地 点：五山校区北区科技园1号楼国重大楼501会议室
报告摘要：
Abstract: Here, we investigate the dependence of metal nanoparticles’ size and shape, at various concentrations, on the power conversion efficiency of organic solar cells (OSCs)[1]. Also, we propose a metal-metal core-shell nanocube (NC) as an advanced plasmonic material for highly efficient OSCs. We covered an Au core with a thin Ag shell as a scattering enhancer to build Au@Ag NCs, showing stronger scattering efficiency than pristine Au nanoparticles (AuNPs) throughout the visible range. Highly efficient plasmonic organic solar cells were fabricated by embedding Au@Ag NCs into an anodic buffer layer, poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)[2, 3].
In the second part, we demonstrate that the metal nanoparticles can improve the performance of OSCs by boosting the internal quantum efficiency (IQE) of the devices even without a notable plasmonic optical gain.[4] A hybrid layer platform in combination of silver nanoparticles (AgNPs) and polyethylenimine-ethoxylated (PEIE) layer maximized the IQE of the OSCs to nearly 100 %. 2D surface characterization confirmed the AgNPs provided the short path and funneled charge carriers to a cathode, which would effectively raise the carrier mobility. Moreover, the hybrid layer doubled the device half-efficiency lifetime due to longer retention of the improved mobility.
Keywords: organic solar cells, metal nanostructures, plasmonic scattering effect, internal quantum efficiency, nano-funneling effect
References
[1] S. Baek et al. “Plasmonic Forward Scattering Effect in Organic Solar Cells: A Powerful Optical Engineering Method”, Scientific Reports, 3, 1726 (2013)
[2] S. Baek et al. “Au@Ag Core-Shell Nanocubes for Efficient Plasmonic Light Scattering Effect in Low Bandgap Organic Solar Cells”, ACS Nano, 8, 3302 (2014)
[3] S. Jeong et al. “Nanoimprinting-induced nanomorphological transition in polymer solar cells: enhanced electrical and optical performance”, ACS Nano 9, 2773 (2015)
[4] Baek et al., “Enhancing the internal quantum efficiency and stability of organic solar cells via metallic nano-funnels,” Advanced Energy Materials (2015) (Online published)
EDUCATION
Ph.D. in Electrical Engineering, Stanford University, Stanford, CA (2010)
M.S. in Electrical Engineering, Seoul National University, Seoul, Korea (2002)
B.S. in Electrical Engineering, Seoul National University, Seoul, Korea (2000)
报告题目：Polymer Designer for High-Performance and Mechanical-Robust All-Polymer Solar Cells
报 告 人：Bumjoon J. Kim
Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Korea
时 间：2015年11月23日（星期一）上午10：45
地 点：五山校区北区科技园1号楼国重大楼501会议室
报告摘要：
Non-ideal bulk-heterojunction morphology (BHJ) of all-polymer solar cells (all-PSCs), i.e., large-scale polymer domain size, reduced ordering of polymer chains, is one of the critical hurdles for producing efficient all-PSCs. To address this issue, we focused on developing the correlation between the polymer microstructure, BHJ morphology and the photovoltaic properties of high performance all-PSCs. As model systems of modulating the molecular weight and the alkyl side chain of polymers, the polymer microstructure and the BHJ blend morphology of all-PSCs are systematically controlled, and thereby we produced high-performance all-PSCs system with 6.7% efficiency, which is the highest value reported to date. More importantly, our all-PSCs exhibited dramatically enhanced strength and flexibility compared with polymer/PCBM devices, with 60x and 470x improvements in elongation at break and toughness, respectively. The superior mechanical properties of all-PSCs afford greater tolerance to severe deformations than conventional polymer-fullerene solar cells, making them much better candidates for applications in flexible and portable devices.
References
[1] Bumjoon J. Kim*, Hanyoung Woo* et al., J. Am. Chem. Soc. 2015, 137, 2359-2365
[2] Bumjoon J. Kim* et al., Advanced Materials 2015, 27, 2466-2471
[3] Bumjoon J. Kim*, Taek-Soo Kim* et al. Nature Comm. 2015, 6:8547 DOI: 10.1038/ncomms9547
[4] Bumjoon J. Kim* et al., ACS Macro Letters, 2014, 3, 1009-1014
[5] Bumjoon J. Kim* et al. ACS Nano, 2014, 8, 10461-10470
EDUCATION
Doctor of Philosophy in Chemical Engineering, University of California, Santa Barbara, 2006.
Thesis Title: Functionalized Polymers for Modifying the Interfacial Properties of Polymers and Inorganic Nanoparticles (Advisor : Prof. Edward J. Kramer)
Bachelor of Science in Chemical Engineering, Seoul National University, 1994-2000 (with honors).
WORK EXPERIENCE
Spring/12-Present: Associate Professor, Department of Chemical & Biomolecular Engineering, KAIST
Fall/08-Winter/11: Assistant Professor (appointed as EWON Assistant Professor), Department of Chemical & Biomolecular Engineering, KAIST
Fall/06-Fall/08: Postdoc Researcher, University of California, Berkeley
(with Prof. Jean M. J. Fréchet)
Summer/06: Postdoc Researcher, Materials Research Laboratory, UCSB
Winter/01-Spring/06: Graduate Research Assistant and Teaching Assistant, UCSB
AWARDS
KAIST Academic Excellence Award (2015)
International Leading Young Scientist Lecturer, The Society of Polymer Science, Japan (2015)
Global Young Academy Fellow (2014)
Young Scientist 2013 Award, World Economic Forum (Davos Forum)
Asian Rising Star Lecture, Asian Chemical Congress (2013)
Wiley-Polymer Society of Korea Young Scientist Award (2011)
Ewon Asssistant Professorship for Distinguished Young Professor at KAIST (2010-2013)
Best Student Award, Gordon Conference (Polymer West), 2005
Seoul National University Honors Fellowship (1994-1996, 1999)B
