Our recent paper together with our colleagues at the Leibniz Institute of Polymer Research Dresden (IPF), is featured in Advanced Science News. This work discusses a novel way to achieve thermally activated delayed fluorescence in polymers through an extension of the HOMO conjugation, which ultimately leads to a smaller splitting between singlet and triplet excited charge transfer states. The paper can be found here: Conjugation-Induced Thermally Activated Delayed Fluorescence (TADF): From Conventional Non-TADF Units to TADF-Active Polymers.
The DPG-Frühjahrstagung der Sektion Kondensierte Materie (SKM) will take place from March 19 – 24 in Dresden this year. Below, you find a list of our group’s contributions throughout the week. We are looking forward to an exciting and fruitful week of discussions and exchange. See you there. (There is even a hashtag for the event: #DPGDD17)
|Mo, 11:00||CPP 7.1||Two-color warm white hybrid OLEDs from thermally activated delayed fluorescence — Ludwig Popp, Paul Kleine, Reinhard Scholz, Ramunas Lygaitis, Olaf Zeika, Axel Fischer, Simone Lenk, and Sebastian Reineke|
|Mo, 11:15||CPP 7.2||Conjugation induced thermally activated delayed fluorescence — Paul Kleine, Qiang Wei, Yevhen Karpov, Xianping Qiu, Hartmut Komber, Karin Sahre, Anton Kiriy, Ramunas Lygaitis, Simone Lenk, Brigitte Voit, and Sebastian Reineke|
|Mo, 12:15||CPP 7.6||Ultrathin metal electrode for bottom-emitting OLEDs on buckled substrates — Yungui Li, Toni Bärschneider, Paul-Anton Will, Yuan Liu, Simone Lenk, and Sebastian Reineke|
|Di, 15:45||CPP 26.8||Absolute optical sensor based on biluminescence — Caterin Salas Redondo and Sebastian Reineke|
|Mi, 18:30||CPP 50.13||controlling excitons in exciplex host systems for efficient white OLEDs — Yuan Liu, Simone Lenk, Karl Leo, and Sebastian Reineke|
|Mi, 18:30||CPP 50.19||Synthesis and characterisation of the new emitters for OLED applications — Ramunas Lygaitis, Olaf Zeika, Reinhard Scholz, Ludwig Popp, Paul Kleine, Simone Lenk, and Sebastian Reineke|
|Mi, 13:00||DS 29.14||Influence of radiative efficiency and dipole orientation on optimal layer thicknesses of monochrome OLEDs for maximum EQE — Paul-Anton Will, Cornelius Fuchs, Reinhard Scholz, Simone Lenk, and Sebastian Reineke|
|Mi, 15:15||DS 34.2||Determination of the molecular orientation in absorptive organic thin films — Christian Hänisch, Simone Lenk, and Sebastian Reineke|
|Mi, 09:30||HL 52.1||Full Range Electrothermal Modeling of Organic Light-emitting Diodes — Axel Fischer, Koen Vandewal, Simone Lenk, and Sebastian Reineke|
|Mi, 15:00||HL 64.19||Diffuse Transmission and Reflection of Light Scattering Polymer Substrates for Organic Light-emitting Diodes — Pen Yiao Ang, Georg Marks, Abdalla Mahmoud, Axel Fischer, Simone Lenk, and Sebastian Reineke|
Ryutaro Komatsu (see below) is currently visiting our group as part of an ongoing exchange program between TU Dresden and Universities from Japan. He is a PhD candidate of Prof. Junji Kido from Yamagata University – good chance to see some of their recent work.
|Mi, 18:30||CPP 50.14||Efficient Deep-blue Pyridimidine-based TADF Emitters Using a Highly Twisted Molecular Skeleton — •Ryutaro Komatsu, Tatsuya Ohsawa, Hisahiro Sasabe, Kohei Nakao, Yuya Hayasaka, and Junji Kido|
In a recent collaboration with our colleagues at the Leibniz Institute of Polymer Research Dresden (IPF), we have developed polymers that show thermally activated delayed fluorescence (TADF) properties with high efficiency. This work has now been published in Advanced Functional Materials under the title: Conjugation-Induced Thermally Activated Delayed Fluorescence (TADF): From Conventional Non-TADF Units to TADF-Active Polymers. Interestingly, the monomer building block does not show TADF but rather only phosphorescence. Hence, the TADF property is induced as a consequence of increased conjugation during polymer formation. Ultimately, the singlet-triplet splitting is reduced in the polymer to allow for TADF. The emitter shows sky-blue emission with roughly 70% PLQY. This report includes the synthesis of the monomer and polymer materials, quantum chemical calculations and a detailed photo-physical characterization.
This announcement comes in parallel with the start of the session Excitons in Organic and Hybrid Systems I of our Symposium EP1, which began 5 minutes ago. Today we are looking in more detail on processes connected with excitons in organic and hybrid systems. We will see sophisticated techniques, modeling, etc.
Here are some keywords that we will come across during the morning program:
- Nanoscale exciton migration
- QM/MM simulation of TADF materials
- Exciton migration in TADF materials
- Exciton transport in colloidal QDs
- Spin oscillations
- Single molecule look on TADF
- Spatial confinement of triplet excitons in rubrene
- Exciton processes in OLEDs
Our invitees are Naomi Ginsberg, William Tisdale, John Lupton, and Grayson Ingram.
Tomorrow, Wednesday March 30, we have two sessions at our Symposium EP1: Organic Excitonic Systems and Devices.
EP1.2: Organic Emitters
The morning focus will be on the emitters itself, where we will here recent progress on various molecular concepts for high performance luminescence. This will include the fundamental studies that excel our current understanding of these emitters. Some things that we will see:
- Design rules for TADF emitters
- Crystalline OLED emission layers for nearly perfect emitter alignment
- Investigation of exciplex emission (electric field dependence and charge separation)
- Nickel-Tetra-Mesityl-Porphoyrin photophysics
- Platinum complexes for high efficiency, color pure blue OLEDs
- Control of molecular orientation
- TADF emitters for LECs and OLEDs
- Biluminescence for optical sensing
- Photophysics of H- and J-aggregates
Our invited speakers of the morning are: Andrew Monkman, Wolfgang Brütting, and Frank Würthner.
EP1.3: Organic Lasers
In the afternoon we switch gears – Its laser time. With the basis of the laser tutorial we had on Monday, we should be all set for some interesting contributions related to laser physics with organics. Important: Due to a serious illness of one of our speakers, the program of the first part of the EP1.3 session has been updated. We will start at 2:00pm rather than the originally planned time of 1:30pm. Please refer to the online program for the latest updates!
Here are some details to the post-lunch session:
- Condensate physics with organic polaritons
- Tunable, narrow line width solid-state lasers
- LED-pumped organic lasers (planar integration) based on luminescent concentration
- Self-assembled colloidal lasers
- Low threshold up-converted laser
- Strong coupling in organic microcavities
- Solvent nano imprint lithography of polymer lasers
- Photoluminescence enhancement in nano cavities
Our afternoon invited speakers are: Stéphane Kéna-Cohen and Alexander J. Kuehne.
Again, a lot of cool and interesting things to look forward to. See you tomorrow!
Tomorrow, Tuesday March 29, we start out with the first Session of our Symposium EP1 Organic Excitonic Systems and Devices. The session runs under the title Organic Light-Emitting Devices (OLEDs). So clearly, we are looking to a collection of recent progress on the OLED technology, where the optimization of efficiency is in the central focus. Here are some keywords that will represent the content of tomorrow:
- Enhanced emission of OLEDs
- Bright NIR OLEDs based on high mobility polymers
- Intrinsic degradation mechanisms in UV and blue OLEDs
- Increased stability of TADF OLEDs
- 100% triplet harvesting in fluorescent OLEDs
- Blue phosphorescent OLEDs
- Absence of triplet up-conversion in anthracene based emitters
- Afterglow OLEDs (a demonstration of biluminescence in OLEDs)
- Origin and control of emitter orientation in OLEDs
Our invited speakers for this session are: Mark Thompson, Stephen R. Forrest, and Jang-Joo Kim.
A couple of impressions from our tutorial connected to the MRS Spring 2016 Symposium EP1: Organic Excitonic Materials and Devices: In short, the room has been packed with more attendees than chairs in the room. Chihaya Adachi started out giving us a complete overview on a class of materials for organic light-emitting diodes, he pioneered, namely thermally activated delayed fluorescence (TADF)-type emitters. He reflected on his initial reports on TADF in 2009, when nobody in the community cared about this concept, lacking competitive efficiency values at the time. Nowadays, these materials are TADF on par with phosphorescence in respect to device efficiency. Listening between the lines, we learned that up to date, the Adachi Lab counts more than 200 TADF molecules made – impressive.
After very limited coffee supply during the break, Stéphane Kéna-Cohan switched gears and gave us a very insightful introduction to the world of organic based lasers. Beginning with the very basics needed for understanding the concepts of lasers in general, we ended up learning the very current developments connected with laser research based on organic materials. The key potential here is seen for its high degree of possible integration, which is for instance important for bio-applications. When discussing the challenges remaining towards the demonstration of an electrically pumped organic laser, Stéphane Kéna-Cohan motivated where the threshold for electrical pumping roughly is using a back-on-an-envelope calculation, which actually fits on an envelope, as the picture below proves.
With the tutorial done, we are looking forward to the upcoming four days of regular symposium program. The sessions will reconvene at a different room: PCC North, 200 Level, Room 227 A. See you tomorrow.