International Research Training Group 1404

Self-organized Materials for Optoelectronics

Within the International Research Training Group (IRTG) scientists from University of Mainz (Germany) and Seoul National University and Hannam University (Korea) will join to work on new materials and basic science, critically needed for optoelectronics, e.g. displays and photovoltaic solar cells.

Within this framework it is our intention to concentrate especially on the aspect of self-organized structures for the desired optoelectronic functions. This is because the self-organization allows the formation and optimization of highly ordered and oriented structures to maximize the desired optoelectronic properties, not possible with randomly structured materials.
Therefore, a number of self-organization principles, including liquid crystalline phases and block copolymers, will be used to obtain the desired functions. In this regard, one critical element is the interfacial phenomena, which underlie the most relevant device characteristics.

Macromolecular Rapid Communications Special Issue

The Macromolecular Rapid Communications' special issue guest-edited by Prof. K. Char and Prof. R. Zentel is published! Many interesting articles presenting the most recent research of the IRTG 1404: Self-Organized Materials for Optoelectronic Applications can be found in this special issue. In addition, several review articles highlight topics such as conducting materials, inroganic-organic hybrids and self-assembly.

More information can be found here and on the MRC hompage.


Nature Communications: Real-space observation of unbalanced charge distribution inside a perovskite-sensitized solar cell

Perovskite-sensitized solar cells have reached power conversion efficiencies comparable to commercially available solar cells used for example in solar farms. In contrast to silicon solar cells, perovskite-sensitized solar cells can be made by solution processes from inexpensive materials. The power conversion efficiency of these cells depends substantially on the charge transfer at interfaces. Here we use Kelvin probe force microscopy to study the real-space cross-sectional distribution of the internal potential within high efficiency mesoscopic methylammonium lead tri-iodide solar cells. We show that the electric field is homogeneous through these devices, similar to that of a p-i-n type junction. On illumination under short-circuit conditions, holes accumulate in front of the hole-transport layer as a consequence of unbalanced charge transport in the device. After light illumination, we find that trapped charges remain inside the active device layers. Removing these traps and the unbalanced charge injection could enable further improvements in performance of perovskite-sensitized solar cells.

More information can be found here.


Nat Commun, 2014, 5, 5001.

Victor W. Bergmann, Stefan A. L. Weber, F. Javier Ramos, Mohammad Khaja Nazeeruddin, Michael Grätzel, Dan Li, Anna L. Domanski, Ingo Lieberwirth, Shahzada Ahmad, Rüdiger Berger

DOI 10.1038/ncomms6001

06.07.2015 - 09.07.2015: Final IRTG meeting in Berlin (Germany)

The final IRTG meeting will take place from July 6th to July 9th 2015 in the "Harnack Haus" in Berlin, Germany
During this last meeting of the IRTG 1404 several outstanding scientists especially from Germany and South Korea will present their current research, newest results and publications. Not only current and former members of the IRTG but also scientists from the industry will be invited as speakers.
In addition this meeting will be a platform for many scientific discussions, gathering new ideas for collaborations (beyond the IRTG 1404) and a final résumé of the successful research done during the last years.
The meeting will be also a chance for saying goodbye, unfortunately in some cases for the very last time, to our Korean friends we had the chance to meet due to the IRTG 1404.

14.07.2014 - 18.07.2014: IRTG meeting, Mainz and Freiburg (Germany)

This year’s IRTG meeting took place from July 14th to July 18th in Mainz and Freiburg, Germany.
During the meeting, which was mainly organized by the new German stipend speakers Bernd Oschmann and Nils Mohri, current research in the field of optoelectronic and energy storage devices was presented by Professors as well as PhD students participating the IRTG.
In addition visiting the MERCK company, the Fraunhofer-Institute for solar energy systems (ISE) and the Department of Microsystems Engineering (IMTEK) were additional interesting events.
The conference schedule can be found here.

17.02.2014 - 22.02.2014: IRTG meeting, Daejon (South Korea)

From the 17th – 22nd February 2014 the IRTG-meeting took place in Daejon (South Korea). At the meeting several outstanding scientists especially from Germany and South Korea presented their current research, newest results and publications.
In addition several students from both, Korean and German sides, presented results which they already achieved during their Ph.D. theses.
The poster presentation, on which IRTG members presented their research, was a perfect chance to discuss problems between the students, find new ideas and start new collaborations.

14.10.2013 - 17.10.2013: IRTG-seminar at the Merian Hotel in Oppenheim
From 14th – 17th of October 2013 an IRTG-seminar for students took place at the Merian Hotel in Oppenheim (

During the seminar many tutorial talks were held by Professors of different Universities with interdisciplinary topics concerning liquid crystals, optoelectronic devices, inorganic nanoparticles and spectroscopic characterization methods.

More information are available here.

26.08.2013 - 29.08.2013: IRTG meeting and 8th German Korean Polymer Symposium 2013 (GKPS2013) in Hamburg, Germany

In august 2013 the 8th German Korean Polymer Symposium 2013 (GKPS2013) was hosted by the University of Hamburg. The IRTG workshop took place in line with this conference.
The meeting focused on Polymer Research at the Interface to Life Science and Technology. 122 participants from all parts of Germany and South Korea could enjoy more than 40 lectures in different fields polymer sciences from bio inspired materials too polymer supported drug delivery up to polymers in optoelectronic applications a broad overview of state it the art polymer science was presented.
For further information see:

Chairs: Patrick Theato, Jürgen Rühe, Rudolf Zentel, Kwang-Sup Lee, Kookheon Char

Chairman - : IRTG meeting
Photo (from left to right): J. Rühe (Freiburg), Kwang-Sup Lee (Hannam, Korea, IRTG), P. Theato (Hamburg, former IRTG), R. Zentel (Mainz, IRTG)

All participants of GKPS
Photo: All participants of GKPS

After the conferences schedule the German and Korean students took the opportunity to go for a 2 days trip to Berlin to visit Laytech, a company for optical sensors and have ones more a student’s seminar. There Aaron Breivolgel gave a short introduction of the IRTG and his research within the IRTG and Laytech gave a short introduction on its young history followed by a tour through the companies’ research facilities. The next day, the students did a seminar, where they presented the research Labs of there groups. The trip ended with a visit of the Bundestagskuppel followed by a lunch.

Students Berlin
Photo: German and Korean students at the Brandenburgertor.

25.02.2013 - 28.02.2013: IRTG Workshop on Self-Organized Materials for Optoelectronics in Seoul, South Korea

During the conference many lectures were given concerning optoelectronic applications, liquid crystals and self-assembly.
In a poster presentation Ph.D. students gave an introduction to their research. It also gave the chance to exchange information and discuss new approaches and ideas for cooperative projects between the Seoul National University, Hannam University and Johannes Gutenberg University Mainz.


Photo: Seoul2013

19.08.2012 - 24.08.2012: International Liquid Crystal Conference ILCC 2012

The "International Liquid Crystal Conference ILCC 2012" with about 850 participants, which is the largest conference in the field of liquid crystals and mesophases in the broader sense, was held 2012 in Mainz.

On this conference the IRTG organized a special session (session 18) on "Self-organization in optoelectronic materials". In addition tutorials were available for the IRTG-members.

Photo: JGU,
some members of the IRTG faculty attending the ILCC 2012 (from left to right):
Yang Ho Na (lecturer) , Changhee Lee (invited leturer), Kookheon Char (organizer of special  session), Rudolf Zentel (chairman if ILCC 2012), Kwang-Sup Lee (invited leturer)


13.04.2012: Lisa zur Borg wins the "Graduate Student Oral Presentation Award"

Lisa zur Borg wins the *"Graduate Student Oral Presentation Award"* at this years Materials Research Society Symposium "Functional Inorganic Nanoparticle-Polymer Composites with Engineered Structures and Coupled Properties" in San Francisco. Congratulations!

11.10.2011: Johannes Gutenberg University Mainz intensifies cooperation with Seoul National University and Peking University

JGU President Georg Krausch visits Seoul and Beijing: Consultations on innovative measures to strengthen and support exchange in research and teaching with top-class Asian universities.

JGU President Professor Dr. Georg Krausch (r.) presents Professor Kookheon Char from the Seoul National University (l.) with the certificate of appointment as a Fellow of the Gutenberg Research College (GRC).

...> Press release (JGU)

Foto: JGU, left to right

Dean of Academic Affairs, Professor Hong-Jong Kim (SNU), Rainer Henkel-von Klaß (JGU), Spokeman of the IRTG, Professor Dr. Rudolf Zentel (JGU), JGU President Professor Dr. Georg Krausch, President of Seoul National University, Porfessor Yeon Ceon Oh, Spokemen of the IRTG, Professor Professor Do Yeung Yoon (SNU) and Professor Byeong-Hyeok Sohn (SNU).

Foto: JGU

Professor Kookheon Char from the Seoul National University (l.) and the german spokeman of the IRTG Professor Dr. Rudolf Zentel (JGU).

Foto: JGU, left to right

Professor Dr. Patrick Théato (WCU-SNU Associate Professor), Professor Kookheon Char from the (SNU), JGU President Professor Dr. Georg Krausch, Professor Dr. Rudolf Zentel (JGU).


07.07.2011: Strom durch künstliche Photosynthese

Deutsch-schweizerischer Materialwissenschaftler Michael Grätzel erhält Gutenberg Research Award der Graduiertenschule MAINZ


28.06.2011: Unterstützung für die Optoelektronik in Mainz: Kookheon Char zum GFK-Fellow ernannt

GFK und Graduiertenschule MAINZ stärken internationale Zusammenarbeit auf dem Gebiet der Optoelektronik mit koreanischer Eliteuniversität Seoul National University



The Research Training Group 1404 Self-organized Materials for Optoelectronics is funded by the DFG (Deutsche Forschungsgemeinschaft)