In this paper entitled ‘Transparent and color-tunable organic light-emitting diodes with highly balanced emission to both sides‘ we demonstrate transparent, two-color, stacked OLEDs that allow for balanced top- and bottom-emission. Making use of ultra thin, composite metal electrodes, this design avoids the use of ITO, such that this architecture can be transferred to flexible substrates. Careful optical design made it possible that the luminance of the device is virtually identical to both viewing directions, which is a great improvement over many earlier device layouts.
Ramon Springer joined the group of Prof. Jang Hyuk Kwon (Department of Information Display, Kyung Hee University, South Korea) to carry out a Master thesis topic within the international Masters course Organic and Molecular Electronics (OME) at the TU Dresden. His thesis task was to develop a white-light emitting, multiple OLED stack based on blue and yellow units to be used in AMOLED displays. Here, aside from the optimization of device efficiency, the color quality and angular stability were parameters to be optimized. His work led to a recent publication in Optics Express entitled “Cool white light-emitting three stack OLED structures for AMOLED display applications“. Congratulations to a very successful research stay abroad.
Our new paper entitled “Adjustable white-light emission from a photo-structured micro-OLED array” published in Light: Science & Applications discusses an approach towards micro-OLED arrays made of differently emitting sub pixels without non-emissive areas. This is achieved using orthogonal lithography techniques in a way that only the first OLED unit is structured while the next one to follow is made in a “fill-the-gap” approach. In this conceptual demonstration, we pair blue and yellow OLEDs in a stripe layout, which can be addressed individually for complete color tunability. Feature sizes of the stripes are down to 20 micrometer.
Its the last day of MRS Spring 2016 and still we are by far not done with our Symposium EP1: Organic Excitonic Systems and Devices. We have a full day of oral presentations split into two major sessions.
EP1.7: Advanced Organic Devices and Modeling
As the title indicates, some new concepts for devices based on organic materials will be central in this session. This is complemented by some efforts on modeling. Keywords for this session are:
- Stretchable electronic structures
- Modeling exciton and polaron dynamics for transient EL in OLEDs
- Nanoscale electrical inhomogeneities in OLEDs
- Visible light communications with organic systems
- Method to predict interface barriers in OLED layers
- Rare-earth up-conversion composites for PV
Our invited speaker in the morning is Graham A. Turnbull. Note: Franky So was not able to come to Phoenix, so that his presentation is cancelled. Klaus Meerholz had his talk already late last night.
EP1.8: Excitonic Charge Transfer States
Our final look in this last session is on charge transfer states and related phenomena. Most naturally, this is the time, where we will have presentations that are closer to photovoltaic properties than in the days before. Actually, this session closes the loop to the first sessions of the week, where we were guided a lot by internal charge transfer states in TADF materials.
Here are some details to the post-lunch session:
- Enhancing exciton dissociation rates at heterojunctions using FRET
- CT state transport at donor-acceptor blends
- Magnetic field modulation of exciton recombination
- Tailoring interfaces using additive engineering
- Generation and modulation of chi^2 optical non-linearities
- Printing highly efficient solution processed solar cells
- Multiple CT states in ordered and disordered systems
Max Shtein will be our invited speaker of the afternoon session.
See you around!
This afternoon, we are progressing with the general scheme of topics with the session EP1.5 Excitons in Organic and Hybrid Systems II of our Symposium EP1. Important: We have one additional speaker in the afternoon: Klaus Meerholz – his talk got shifted from Friday to this session. The following topics we will see:
- NIR EL from surface plasmons
- Area light-emitting transistors
- Multiple FRET pathways
- Topological phases in organic materials
- Manipulating Excitons with plasmonic nanoantennas
- Singlet exciton fission
- Real time exciton diffusion mapping
- Organic memory devices
Our invited speakers for the afternoon are Jana Zaumseil, Joel Yuen-Zhou, Gleb M. Akselrod, and Klaus Meerholz.
See you in a bit!
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!