Method for manufacturing an improved cathode to cathode-lead contact in an organic electroluminescent device.
Publication Date: 2002-Feb-04
The IP.com Prior Art Database
Method for manufacturing an improved cathode to cathode-lead contact in an organic
This disclosure relates to an organic electroluminescent device. The basic
structure of these devices is a light emissive organic layer sandwiched between an
anode layer and a cathode layer, respectively. The figure shows the cross-sectional
structure of a typical organic electroluminescent (EL) device. Said device is typically
fabricated on a transparent substrate, such as glass, which is coated with a transparent
first electrode, such as indium-tin-oxide (ITO). This ITO coated substrate is covered
with at least a layer of an organic electroluminescent material and a final layer
forming a second electrode, which is typically a metal or alloy. Other layers maybe
added to the device, for example to improve charge transport between the electrodes
and the electroluminescent material.
Typically the substrate further comprises leads for making contact to the
cathode(s) of the device(s) on the substrate. These leads are made up from a material
having a low electrical resistivity, such as a metal or alloy.
During the production process, an electrical contact between the leads on the
substrate and the cathode has to be created by making vias in the organic material.
These vias are created by a dry etching technique, such as laser ablation. Presently,
these vias are ablated down to the lead metal. Subsequently, the second electrode
material (cathode) is deposited by vapour deposition on top of the layer(s) of organic
material. Said second electrode material also fills up the vias and establishes an
electrical contact between the cathode and the cathode lead.
It was found that a better and more stable contact between the cathode material
and the cathode lead can be established when the cathode leads are made-up from a
layer ITO on top of the substrate, which is covered by a layer of lead metal. During the
production process, the vias must be ablated down to the ITO layer which is in
electrical contact with the cathode lead. Subsequently, the second electrode material
(cathode) is deposited as described above, which material fills up the vias and
establishes an improved electrical contact between the cathode and the cathode lead
via the ITO layer.
Cross section of current situation
ITO"" t: *3tesS' substrate
Cross section of improved contact
H.P. van Broekhuyzen
Improved configuration of an energy recovery circuit
Electroluminescent displays (EL displays) and other types like plasma displays form a
capacitive load for the drivers. Due to the combination of high driving voltages (in the
order of magnitude of 200V), and a high frequency (of 10 kHz to more than 100 kHz),
the power losses caused by charging and discharging the capacitive load is quite high.
By using resonant circuits, the...