OLED Displays and Lighting
OLED Displays and Lighting
Organic Light Emitting Diodes (OLEDs) have gained considerable momentum as a new technology for displays and lighting within the last decade. Heraeus provides a variety of dispersions based on Poly(3,4-ethylenedioxythiophene) or PEDOT, that help to improve processing and performance of OLEDs. The most common OLED set-ups comprising Clevios™ are shown below:
Clevios™ fulfills in OLEDs two functions:
- as hole-injection layer (HIL) in between the anode and the OLED layer stack
- as transparent, conductive electrode, typically the anode
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ITO free OLEDs
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Clevios™PEDOT:PSS as a transparent, conductive electrode in OLED devices. Highly conductive Clevios™ PEDOT:PSS dispersions are suitable to form transparent conductive electrodes in OLEDs. They are typically employed as alternatives to layers of transparent conductive oxides such as indium-tin-oxide (ITO). ITO-free OLEDs as large as 10x10 cm have been realized with Clevios™.
Key Advantages :
- can be deposited by various means, e.g. spin-coating, ink jet printing, slit-coating and others
- low baking temperatures of 130°C or lower
- no crack formation when being bent, ideal for flexible devices
- low sheet resistance at high transparency levels, to <200 Ohm /sq at 88% T
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Clevios™ for Hole Injection Layers (HILs) in OLEDs
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Clevios™ HILs are tailored materials to be introduced into OLEDs as the layer between the anode, e.g. ITO, and the organic layer stack. These dispersions are advantageous as they:
- form ohmic contacts with TCOs and metals
- improve hole-injection into the OLED layer stack, as they exhibit high work function and form dipole layers at the interface
- reduce the probability for electrical shorts by smoothing defects on the substrate’s surface
- are conductive and highly transparent
