Matthias Schober

Technische Universität Dresden, Dresden, Saxony, Germany

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Publications (6)50.5 Total impact

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    ABSTRACT: In multilayer white organic light-emitting diodes the electronic processes in the various layers-injection and motion of charges as well as generation, diffusion and radiative decay of excitons-should be concerted such that efficient, stable and colour-balanced electroluminescence can occur. Here we show that it is feasible to carry out Monte Carlo simulations including all of these molecular-scale processes for a hybrid multilayer organic light-emitting diode combining red and green phosphorescent layers with a blue fluorescent layer. The simulated current density and emission profile are shown to agree well with experiment. The experimental emission profile was obtained with nanometre resolution from the measured angle- and polarization-dependent emission spectra. The simulations elucidate the crucial role of exciton transfer from green to red and the efficiency loss due to excitons generated in the interlayer between the green and blue layers. The perpendicular and lateral confinement of the exciton generation to regions of molecular-scale dimensions revealed by this study demonstrate the necessity of molecular-scale instead of conventional continuum simulation.
    Nature Material 04/2013; 12(7). DOI:10.1038/nmat3622 · 36.50 Impact Factor
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    ABSTRACT: We present investigations of top emitting organic light emitting devices (OLED) comprising n- and p-doped organic charge transport layers. It has been found previously that in comparison to noninverted p-i-n OLEDs, inverted n-i-p OLEDs show reduced device performances after fabrication. These differences can be eliminated by subsequent thermal annealing of the whole n-i-p OLED. After this process, the n-i-p OLED exhibits a superior low driving voltage of 2.9 V at 1000 cd/m(2) and shows an increase in external quantum efficiency from 11% to almost 15% which we ascribe to a modified charge balance within the intrinsic organic emission layer. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3559847]
    Applied Physics Letters 12/2011; 98:083304. DOI:10.1063/1.3559847 · 3.30 Impact Factor
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    ABSTRACT: We present a simulation model for the analysis of charge-carrier transport in organic thin-film devices, and apply it to a three-color white hybrid organic light-emitting diode (OLED) with fluorescent blue and phosphorescent red and green emission. We simulate a series of single-carrier devices, which reconstruct the OLED layer sequence step by step. Thereby, we determine the energy profiles for hole and electron transport, show how to discern bulk from interface limitation, and identify trap states.
    Physical review. B, Condensed matter 10/2011; 84(16):165326-. DOI:10.1103/PhysRevB.84.165326 · 3.66 Impact Factor
  • Matthias Schober · Selina Olthof · Mauro Furno · Bjoern Luessem · Karl Leo
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    ABSTRACT: We introduce single-carrier devices with electrical doped layers as a concept for the characterization of charge-carrier transport in organic semiconductors. In this approach, individual organic layers from a multilayer device are investigated in single-carrier test devices, where they are enclosed by symmetrically arranged electrical doped layers of equal thickness and composition. Single carrier devices without electrical doped layers are usually difficult to interpret due to an uncertainty about interface dipole effects between the metal contacts and pristine organic layers. In comparison, our devices show Ohmic contacts at the electrodes as well as zero built-in voltage and thus allow a more direct insight into charge-carrier transport. State-of-the-art simulation models are applied to analyze current-voltage characteristics and evaluate crucial parameters such as energy barriers between adjacent organic layers and mobilities. © 2010 American Institute of Physics.
    Applied Physics Letters 12/2010; 97(1):013303. DOI:10.1063/1.3460528 · 3.30 Impact Factor
  • Source
    S. Olthof · R. Meerheim · M. Schober · K. Leo
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    ABSTRACT: We use photoelectron spectroscopy to study the electronic structure and energy level alignment throughout an organic light-emitting diode. The structure under investigation is a state-of-the-art long-living red phosphorescent device composed of doped charge-injection layers, charge-blocking layers, and an emission layer. By consecutively building up the whole device, the key parameters of every interface are measured. Our results show that the doped layers have a significant influence on the device energetics, especially in controlling the built-in potential, and that there are mostly only small dipoles present at the interfaces of the intrinsic organic layers.
    Physical Review B 12/2009; 79. DOI:10.1103/PhysRevB.79.245308 · 3.74 Impact Factor
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    ABSTRACT: In this contribution, we present simulation results of an emitter doped phosphorescent OLED. An alternative method for the determination of correct electrical input parameters is proposed. The exciton profile from the electrical simulation is used to simulate angle dependent emission spectra. Comparison with experimental data demonstrates the feasibility of the underlying physical models.
    SID Symposium Digest of Technical Papers 01/2008; 39(1). DOI:10.1889/1.3069685

Publication Stats

80 Citations
50.50 Total Impact Points


  • 2009–2013
    • Technische Universität Dresden
      • Institut für Angewandte Photophysik
      Dresden, Saxony, Germany