My watch list
my.chemeurope.com  
Login  

OLED: Nanometer-thin layer improves efficiency

15-Mar-2018

© Max Planck Institute for Polymer Research

Visualization of a current through an OLED, flowing via a thin molecular layer (center) from an electrode (left) to an organic semiconductor (right).

Scientists at the Max Planck Institute for Polymer Research in Mainz, Germany, have received an unexpected result: They have discovered a new method to improve contacts in OLEDs. This new approach leads to a higher energy efficiency and can be used in almost any organic semiconductor element.

Organic light-emitting diodes (OLEDs) are used as light sources in high-quality smartphone displays and large-area high-end products such as OLED televisions. The main active component in an OLED is a light-emitting layer of an organic semiconductor, which converts electrical energy into visible light. In an OLED, the organic semiconducting layer is situated between two electrodes; by applying a voltage across these two electrodes, an electric current passes through the OLED, which is converted into visible light.

However, for many organic semiconductors, especially for blue- or ultraviolet-emitting materials, it is difficult to inject the current from the positive electrode into the OLED. This leads to low efficiencies in OLEDs.

Dr. Gert-Jan Wetzelaer, Group Leader at the Max Planck Institute for Polymer Research in Mainz, Germany, has recently discovered a way of improving the current injection from the positive electrode in OLEDs. Wetzelaer and his team have covered the positive electrode with an ultrathin layer of another organic semiconductor as a spacer layer between the electrode and the light-emitting organic semiconductor. Wetzelaer said: “The result was unexpected. This nanometer-thin layer facilitates charge transfer between the electrode and the organic semiconductor. Although it seems to be illogical at first, eliminating physical contact between electrode and semiconductor actually improves the electrical contact.”

Improved contacts in semiconductors

Improving electrical contact with an ultrathin interlayer greatly increases the efficiency of ultraviolet-emitting OLEDs. The scientists at the MPI for Polymer Research have demonstrated this improvement of electrodes for a large number of organic semiconductors and for different spacer layers. Professor Paul Blom, Director at the Max Planck Institute for Polymer Research and head of its Molecular Electronics Department, is convinced: “This simple method of covering electrodes in OLEDs with an ultrathin layer for current-injection improvement is a resounding success for technical application in high-end electronics.”

Gert-Jan Wetzelaer and his research team are very confident that this new approach for fabricating improved contacts can be used in basically any organic-semiconductor device, which could boost their performance now.

Facts, background information, dossiers
More about MPI für Polymerforschung
  • News

    Photoexcited graphene puzzle solved

    Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for light detectors can offer significant improvements with respect to materials being used nowadays. For example, graphene can detect l ... more

    How does water melt? Layer by layer!

    We all know that water melts at 0°C. However, already 150 years ago the famous physicist Michael Faraday discovered that at the surface of frozen ice, well below 0°C, a thin film of liquid-like water is present. This thin film makes ice slippery and is crucial for the motion of glaciers. Si ... more

    Borophene: A very promising 2D material

    "Borophene", a 2-dimensional layer of boron atoms, holds the electronic properties which researchers try to implement in graphene – and even more. In the latest issue of Science, Hermann Sachdev, a researcher from Professor Müllen’s department at the Max Planck Institute for Polymer Resear ... more

More about Max-Planck-Gesellschaft
  • News

    Light-induced superconductivity under high pressure

    A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on ... more

    Oxygen: A blessing and a curse for nanostructured alloying

    Severe plastic deformation and powder processing techniques are used to produce nanostructured materials with tailor-made compositions and without the effort of precasting. They allow the production of novel metallic nanocrystalline materials by mechanically alloying immiscible elements. Ox ... more

    Molecules Brilliantly Illuminated

    Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of health. Researchers at the Laboratory for Attosecond Physics (LAP) – a joint venture between Ludwig-Maximilians-Universität (LMU) and ... more

Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE