Encapsulation of OLEDs
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Encapsulation of an OLED with a POLO ultra-barrier film by an encapsulation technology |
Organic light emitting diodes (OLEDs) are distinguished for example by their high energy efficiency and laminar emission of light. That makes them interesting for a number of applications as displays, signage, and lighting.
The active polymers as well as the electrode material are readily degraded by oxygen and water which results in a loss of their function. For the application these parts of a device require protection by a hermetic encapsulation.
As shown in the scheme the oxygen and the water can penetrate through various paths. One of these paths can be formed at the interface between the encapsulation material and the adhesive. The substrate and the cover have surfaces with a high surface energy. Therefore, they readily adsorb substances from the environment. Typically, such surfaces are covered by several nm of adsorbed water.
10 nm of water reacts with 15 nm Ca.
Surface pre-treatment helps to obtain a high quality encapsulation. This is one example how surface science and technology can help to produce organic electronic devices.
As shown in the scheme the oxygen and the water can penetrate through various paths. One of these paths can be formed at the interface between the encapsulation material and the adhesive. The substrate and the cover have surfaces with a high surface energy. Therefore, they readily adsorb substances from the environment. Typically, such surfaces are covered by several nm of adsorbed water.
10 nm of water reacts with 15 nm Ca.
Surface pre-treatment helps to obtain a high quality encapsulation. This is one example how surface science and technology can help to produce organic electronic devices.
The complete process from loading the substrate till unloading the final OLEDs takes less than 2 minutes and has quite some opportunities for optimization.