(Lecture, Jan 26) Impact of Side Chain Engineering and Molecular Weight Control of Polymer Acceptors in All-Polymer Solar Cells
time: 2018-01-15

Topic: Impact of Side Chain Engineering and Molecular Weight Control of Polymer Acceptors in All-Polymer Solar Cells
Speaker: Prof. Bumjoon J. Kim , KAIST
Time: 10:00, Jan 26, 2018
Venue: Room 501, Building of State Key Laboratory of Luminescent Materials and Devices, Wushan Campus

Polymer-polymer solar cells (so called all-polymer solar cells, all-PSCs) have emerged as good candidates for applications in flexible and portable devices because these devices offer much superior thermal and mechanical endurance than conventional polymer-fullerene solar cells. However all-PSCs often suffer from low short-circuit current density, and thus power-conversion efficiency. In this talk, we will discuss three major challenges that need to be addressed in improving the photovoltaic performance of all-PSCs, i.e., (1) the low electron transport ability of polymer acceptor, (2) the precise control of molecular packing structure and orientation of polymer acceptor, and (3) polymer donor-acceptor demixing (unfavorable blend morphology). We will also discuss the advantage and potential of all-PSCs over polymer-fullerene PSCs systems. Finally, based on comprehensive understanding gained from the comparative study, we will present our molecular design strategies of either polymer donor or acceptor, which allow to overcome each recognized challenges in all-PSCs. For instance, main backbone/side chain engineering, molecular weight control systematically modulated molecular packing, orientation and blend morphology in all-PSCs, thus boosting light-conversion efficiency up to 8%. Our results provide the guidelines for the design of polymer donors and acceptors for high-performance all-PSCs, which will offer a great opportunity for successful realization of flexible and portable power generators.

[1] B. J. Kim*, T. S. Kim* et al. Nature Comm. 2015, 6, 8547
[2) B. J. Kim*, H. Y. Woo* et al. J. Am. Chem. Soc. 2015, 137, 2359
[3] B. J. Kim* et al. Advanced Materials 2015, 27, 2466
[4) B. J. Kim*, S.H. Jin* et al. Advanced Materials 2016, 28, 10016
[5] B. J. Kim* et al. Accounts of Chemical Research 2016, 49, 2424


Bumjoon Kim is Professor in the Department of Chemical and Biomolecular Engineering at KAIST since 2008. He completed his doctorate in 2006 under the guidance of Prof. Edward Kramer at the University of California, Santa Barbara. Then, he worked with Prof. Jean Fréchet at the University of California, Berkeley. His research interests include development of novel functional hybrid materials based on the control of nanoparticles location within polymers, and design of new conducting polymers for organic photovoltaics with high performance and stability. He has published more than 140 research articles, and holds about 50 patents. He was appointed as Ewon Associate Professor at KAIST (2010-2013). Also, he received the KAIST Academic Excellence Award (2015) and he was selected as 2013 Young Scientist by the World Economic Forum (DAVOS Forum). He currently serves as Editorial Advisory Board of Macromolecules, ACS Macro Letters, Chemistry of Materials (ACS) and J. Mater. Chem. A (RSC).