Dr. Reinhard Scholz Profile

Dr. Reinhard Scholz

at TU Dresden

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Author

Publications (11)

Proceedings Article | 23 May 2018 Presentation

Warm-white hybrid emission from TADF and phosphorescence and its application in OLEDs (Conference Presentation)

Ludwig Popp, Paul Kleine, Ramunas Lygaitis, Reinhard Scholz, Simone Lenk, Sebastian Reineke

Proceedings Volume 10687, 1068707 (2018) https://doi.org/10.1117/12.2307440

KEYWORDS: Organic light emitting diodes, Phosphorescence, Excitons, Luminescence, Light sources and illumination, External quantum efficiency, Televisions, OLED lighting, Molecules, Thin films

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Organic light-emitting devices (OLEDs) are already widely used for common applications like OLED TVs or smartphone displays. Nevertheless, it is still a challenge for both science and industry to develop OLED systems for lighting applications that combine true-color white light, high efficiencies and high brightness at the same time. Since white emission in OLEDs is usually a combination of two or more different emitters with individual colors it is necessary that all included systems are efficient. It has been shown that the concept of thermally activated delayed fluorescence (TADF) allows to synthesize very efficient light-emitting molecules with various emission colors. In our work, we use the sky-blue TADF emitter 9-[2,3,4,5-tetra(carbazol-9-yl)-6-(trifluoromethyl)phenyl]carbazole (5CzCF3Ph) with an emission maximum at a wavelength of 495 nm in thin films, reaching a photoluminescence quantum yield of 70 %. In an OLED, the emitter delivered up to 18 % external quantum efficiency (EQE). This is beyond the theoretical limit of conventional fluorescent OLEDs. To achieve warm-white emission, we combine the sky-blue emission of 5CzCF3Ph with the red emission of the common phosphorescent emitter Ir(MDQ)2(acac) within one emission layer. Due to the very broad blue emission (FWHM ~ 95 nm), a dedicated deep blue emitter becomes obsolete and it is possible to tune the combined two-color spectrum in such a way, that a high color rendering index of over 80 and correlated color temperatures about 2800 K can be obtained by this strategy. EQEs of up to 17 % and luminous efficacies of 16 lm/W have been measured for the hybrid white OLEDs. This two-color concept paves the way towards future utilization of TADF emitters in lighting applications by simplifying the required sequence of organic layers inside the OLED. In our approach, the excitons are formed mostly on the TADF emitter itself. To achieve a suitable amount of red light for the white emission, it is necessary to enable efficient exciton transition pathways between 5CzCF3Ph and Ir(MDQ)2(acac). Due to the variety of potential local and charge-transfer excited states in the emitter system, there are several probable scenarios for the energy transfer. Utilizing time-correlated single photon counting (TCSPC) with a wavelength-sensitive detection, we study the exciton decay of both the TADF prompt and delayed fluorescence as well as the phosphorescent emission channel in detail. With this technique, we deliver a thorough investigation of the exciton transfer and exchange mechanisms in the emitter system of our warm-white hybrid OLEDs.

Proceedings Article | 2 November 2016 Presentation

Organic permeable-base transistors - superb power efficiency at highest frequencies (Conference Presentation)

Markus Klinger, Axel Fischer, Felix Kaschura, Reinhard Scholz, Björn Lüssem, Bahman Kheradmand-Boroujeni, Frank Ellinger, Daniel Kasemann, Karl Leo

Proceedings Volume 9943, 99430I (2016) https://doi.org/10.1117/12.2237719

KEYWORDS: Transistors, Field effect transistors, Thin films, Photomasks, Semiconductors, Electrodes, Electronics, Flexible displays, System identification, Sensors

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Proceedings Article | 5 October 2015 Presentation

Exciton binding energy limitations in organic materials and potentials for improvements (Presentation Recording)

Stefan Kraner, Reinhard Scholz, Eric Müller, Martin Knupfer, Christian Koerner, Karl Leo

Proceedings Volume 9567, 95670E (2015) https://doi.org/10.1117/12.2187831

KEYWORDS: Excitons, Organic materials, Polymers, Solar energy, Energy efficiency, Molecules, Dielectrics, Organic photovoltaics, Absorption, Solar cells

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Proceedings Article | 22 September 2015 Presentation + Paper

OLEDs: light-emitting thin film thermistors revealing advanced self-heating effects

Axel Fischer, Thomas Koprucki, Annegret Glitzky, Matthias Liero, Klaus Gärtner, Jacqueline Hauptmann, Sebastian Reineke, Daniel Kasemann, Björn Lüssem, Karl Leo, Reinhard Scholz

Proceedings Volume 9566, 95661A (2015) https://doi.org/10.1117/12.2186940

KEYWORDS: Organic light emitting diodes, Resistance, Light sources and illumination, Electrodes, OLED lighting, Switching, Instrument modeling, Positive feedback, Thin films, Physics

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Proceedings Article | 8 October 2014 Paper

Surface plasmon polariton modification in top-emitting organic light-emitting diodes for enhanced light outcoupling

Cornelius Fuchs, Tobias Schwab, Martin Wieczorek, Malte Gather, Simone Hofmann, Karl Leo, Reinhard Scholz

Proceedings Volume 9183, 91831Z (2014) https://doi.org/10.1117/12.2061585

KEYWORDS: Organic light emitting diodes, Metals, Refractive index, Dielectrics, External quantum efficiency, Dispersion, Interfaces, Optical microcavities, Opacity, Electroluminescent displays

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Proceedings Article | 27 September 2013 Paper

Improved light outcoupling and mode analysis of top-emitting OLEDs on periodically corrugated substrates

Tobias Schwab, Cornelius Fuchs, Reinhard Scholz, XuanHua Li, Fengxian Xie, Wallace Choy, Karl Leo, Malte Gather

Proceedings Volume 8829, 88291I (2013) https://doi.org/10.1117/12.2023222

KEYWORDS: Organic light emitting diodes, Scattering, Light scattering, Waveguides, Photoresist materials, OLED lighting, Waveguide modes, Dispersion, Destructive interference, External quantum efficiency

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Proceedings Article | 23 September 2005 Paper

Combined Raman spectroscopic and electrical characterization of the conductive channel in pentacene based OFETs

Beynor Paez S., Ilja Thurzo, Georgeta Salvan, Reinhard Scholz, Dietrich Zahn, H. von Seggern

Proceedings Volume 5940, 59400F (2005) https://doi.org/10.1117/12.617511

KEYWORDS: Raman spectroscopy, Field effect transistors, Spectroscopy, Gold, In situ metrology, Interfaces, Electrodes, Dielectrics, Molecules, Metals

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Proceedings Article | 21 September 2005 Paper

Comparison between the charge carrier mobilities in pentacene OFET structures as obtained from electrical characterization and potentiometry

R. Scholz, A.-D. Müller, F. Müller, I. Thurzo, B. Paez, L. Mancera, D. Zahn, C. Pannemann, U. Hilleringmann

Proceedings Volume 5940, 59400I (2005) https://doi.org/10.1117/12.617004

KEYWORDS: Field effect transistors, Resistance, Capacitance, Dielectrics, Oxides, Interfaces, Gold, Molecules, Metals, Atomic force microscope

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Proceedings Article | 17 November 2003 Paper

Combined electrical and Raman characterization of C60-based organic field effect transistors

Beynor Paez, Matthias Bartzsch, Georgeta Salvan, Reinhard Scholz, Thorsten Kampen, Dietrich Zahn

Proceedings Volume 5217, (2003) https://doi.org/10.1117/12.506019

KEYWORDS: Raman spectroscopy, Field effect transistors, Molecules, Molecular spectroscopy, In situ metrology, Fullerenes, Raman scattering, Phonons, Polarizability, Argon ion lasers

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Proceedings Article | 17 November 2003 Paper

Interaction of metals with perylene derivatives as a model system for contact formation in OFET structures

Beynor Paez, Georgeta Salvan, Reinhard Scholz, Thorsten Kampen, Dietrich Zahn

Proceedings Volume 5217, (2003) https://doi.org/10.1117/12.505905

KEYWORDS: Metals, Raman spectroscopy, Molecules, Silver, Chemical species, Interfaces, Field effect transistors, Indium, Raman scattering, Plasmons

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Proceedings Article | 27 October 2003 Paper

Influence of the electron-phonon interactions on the transport properties at the molecular scale

Alessandro Pecchia, Marieta Gheorghe, Aldo Di Carlo, Thomas Niehaus, Reinard Scholz, Thomas Frauenheim, Paolo Lugli

Proceedings Volume 5219, (2003) https://doi.org/10.1117/12.507127

KEYWORDS: Molecules, Oscillators, Scattering, Monte Carlo methods, Quantum computing, Computer simulations, Molecular interactions, Electrons, Chemical species, Phonons

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Showing 5 of 11 publications

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