Bumjoon+Kim
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A KAIST Research Team Develops High-Performance Stretchable Solar Cells
With the market for wearable electric devices growing rapidly, stretchable solar cells that can function under strain have received considerable attention as an energy source. To build such solar cells, it is necessary that their photoactive layer, which converts light into electricity, shows high electrical performance while possessing mechanical elasticity. However, satisfying both of these two requirements is challenging, making stretchable solar cells difficult to develop.
On December 26, a KAIST research team from the Department of Chemical and Biomolecular Engineering (CBE) led by Professor Bumjoon Kim announced the development of a new conductive polymer material that achieved both high electrical performance and elasticity while introducing the world’s highest-performing stretchable organic solar cell.
Organic solar cells are devices whose photoactive layer, which is responsible for the conversion of light into electricity, is composed of organic materials. Compared to existing non-organic material-based solar cells, they are lighter and flexible, making them highly applicable for wearable electrical devices. Solar cells as an energy source are particularly important for building electrical devices, but high-efficiency solar cells often lack flexibility, and their application in wearable devices have therefore been limited to this point.
The team led by Professor Kim conjugated a highly stretchable polymer to an electrically conductive polymer with excellent electrical properties through chemical bonding, and developed a new conductive polymer with both electrical conductivity and mechanical stretchability. This polymer meets the highest reported level of photovoltaic conversion efficiency (19%) using organic solar cells, while also showing 10 times the stretchability of existing devices. The team thereby built the world’s highest performing stretchable solar cell that can be stretched up to 40% during operation, and demonstrated its applicability for wearable devices.
< Figure 1. Chemical structure of the newly developed conductive polymer and performance of stretchable organic solar cells using the material. >
Professor Kim said, “Through this research, we not only developed the world’s best performing stretchable organic solar cell, but it is also significant that we developed a new polymer that can be applicable as a base material for various electronic devices that needs to be malleable and/or elastic.”
< Figure 2. Photovoltaic efficiency and mechanical stretchability of newly developed polymers compared to existing polymers. >
This research, conducted by KAIST researchers Jin-Woo Lee and Heung-Goo Lee as first co-authors in cooperation with teams led by Professor Taek-Soo Kim from the Department of Mechanical Engineering and Professor Sheng Li from the Department of CBE, was published in Joule on December 1 (Paper Title: Rigid and Soft Block-Copolymerized Conjugated Polymers Enable High-Performance Intrinsically-Stretchable Organic Solar Cells).
This research was supported by the National Research Foundation of Korea.
2024.01.04 View 4999 -
Professor Bumjoon Kim Named Scientist of the Month
Professor Bumjoon Kim from the Department of Chemical and Biomolecular Engineering won January’s Scientist of the Month Award presented by the Ministry of Science and ICT (MSIT) and the National Research Foundation of Korea (NRF) on January 6. Professor Kim also received 10 million won in prize money.
Professor Kim was recognized for his research in the field of fuel cells. Since the first paper on fuel cells was published in 1839 by the German chemist Friedrich Schonbein, there has been an increase in the number of fields in which fuel cells are used, including national defense, aerospace engineering, and autonomous vehicles.
Professor Kim developed carbonized block copolymer particles with high durability and a high-performance fuel cell. Block copolymers are two different polymers cross-linked into a chain structure. Various nanostructures can be made effectively by using the attractive and repulsive forces between the chains.
Professor Kim used the membrane emulsification technique, employing a high-performance separation membrane to develop a platform that makes the mass production of highly durable carbonized particles possible, which he then used to develop high-performance energy devices like fuel cells.
The carbonized particles designed by Professor Kim and his research team were used to create the world’s more durable fuel cells that boast outstanding performance while using only five percent of the costly platinum needed for existing commercialized products.
The team’s research results were published in the Journal of the American Chemical Society and Energy Environmental Science in May and July of last year.
“We have developed a fuel cell that ticks all the boxes including performance, durability, and cost,” said Professor Kim. “Related techniques will not be limited to fuel cells, but could also be applied to the development of various energy devices like solar cells and secondary cells,” he added.
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2021.01.22 View 9679 -
The 10th KINC Fusion Research Awardees
The KAIST Institute for NanoCentury (KINC) recognized three distinguished researchers whose convergence studies made significant impacts. The KINC presented the 10th KINC Fusion Research Awards during a ceremony that took place at KAIST’s main campus in Daejeon on May 19.
This year’s ‘best’ convergence research award went to a joint research group led by Professor Hee Tak Kim from the Department of Chemical and Biomolecular Engineering and Professor Sang Ouk Kim from the Department of Materials Science and Engineering. Their research, featured in the December 27 issue of Advanced Materials as a front cover article last year, introduced the world’s first high-energy efficiency, membraneless, flowless, zinc-bromine battery. This study, in which research professor Gyoung Hwa Jeong, postdoctoral researcher Yearin Byun, and PhD candidate Ju-Hyuck Lee took part as co-lead authors, is deemed as an example of a best practice in convergence research in which two groups’ respective expertise in the fields of carbon materials and electrochemical analysis created a synergistic effect.
Professor Bumjoon Kim from the Department of Chemical and Biomolecular Engineering was also recognized for having published the most interdisciplinary research papers on polymer electronics and nanomaterials at home and abroad.
Professor Hee-Tae Jung, the Director of KINC and the host of the KINC Fusion Research Awards, said, “The KINC is happy to announce the 10th awardees in nano-fusion research this year. Since convergence is crucial for making revolutionary changes, the importance of convergence studies should be recognized. Our institute will spare no effort to create a research environment suitable for convergence studies, which will be crucial for making a significant difference.”
The KINC was established in June 2006 under the KAIST Institute with the mission of facilitating convergence studies by tearing down boarders among departments and carrying out interdisciplinary joint research. Currently, the institute is comprised of approximately 90 professors from 13 departments. It aims to become a hub of university institutes for nano-fusion research.
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2020.05.19 View 11727