OLEDs / Organic Electronics
Organic light emitting diodes (devices) or OLEDs are monolithic, solid-state devices that typically consist of a series of organic thin films sandwiched between two thin-film conductive electrodes. When electricity is applied to an OLED, under the influence of an electrical field, charge carriers (holes and electrons) migrate from the electrodes into the organic thin films until they recombine in the emissive zone forming excitons. Once formed, these excitons, or excited states, relax to a lower energy level by giving off light (electroluminescence) and/or unwanted heat.
Manufacturing of OLED panels
A complete usable OLED panel requires next to the substrate, which carries the active light-emitting layers, a backplane (the electronics) and an encapsulation layer. The latter is strictly required and critical not only to protect the nanometer-thin OLED layers from mechanical damages, but also because of the sensitivity of the used materials to oxygen and moisture.
So until the OLED is encapsulated it is strictly required to process them under inert conditions with oxygen and moisture values < 1 ppm. With increasing substrate sizes the impact of airborne particles becomes more and more critical. Particles that are unintentionally deposited on the active layers of the OLED can be the starting point for so-called pinholes which effect the quality of the display and ca reduce the overall yield of the manufacturing process.
In a well-designed system those parts of the manufacturing process in which the OLED is still encapsulated are run under so called inert cleanroom conditions. Such systems not only reach oxygen and moisture values < 1 ppm but also reach cleanroom conditions of ISO 1 according to ISO 14644-1.
Currently most OLED displays are made using vacuum evaporation processes, utilizing a so called shadow mask or FMM (Fine Metal Mask) to pattern it. For smaller substrates this is a relatively simple method, but requires significant experience in the equipment design when applied in mass manufacturing. Next to the difficulties in scaling-up to larger substrates another main disadvantage of this technique is the inefficiency of the process as a lot of material is wasted.
Some OLED materials are soluble allowing them to be deposited using printing methods - mostly ink-jet printing. Currently tremendous efforts are undertaken to establish and optimize inkjet-printing processes for OLED. If successful it would allow to increase the material utilisation to unprecedented levels and thus cutting manufacturing costs down significantly.
In recent years the well-established technology of slot-die-coating (SDC) found its way into OLED material processing. Especially when large areas have to be coated with a highly homogeneous layer this coating method outperforms many other coating technologies. In roll-to-roll processes (R2R) in which processing speed plays an important factor, SDC proved its versatility, repeatability and robustness which are important factors in research and manufacturing environments.
Our recommendations for the OLED sector:
MB-Laminar-Flow
MBRAUN is one of the few companies to achieve an ISO Class 2 cleanroom standard and O2 and H2O <1 ppm. We adopted the well established cleanroom concepts, transferred the core technical elements into the inertgas technology and combined it with in-house developments like the HPL membrane.
OPTIvap
The MB-OptiVap series is the current high-end solution in MBRAUN's deposition tool series. Designed for the requirements of specialized research up to pilot scale production, these tools find frequent use in industrial laboratories and state-of-the-art Universities throughout the world.
Ovens
MBRAUN glovebox systems can be optionally equipped with ovens for dewatering or curing sensitive materials under controlled conditions.
All MBRAUN oven systems are specifically designed for integration into inert environments and are also available as stand-alone units.
Hot Plates
MBRAUN Glovebox systems can be optionally equipped with hotplate, either for removing water and/or solvents from substrate surfaces or for curing sensitive materials under controlled conditions.
UV Press
MBRAUN has developed and adapted a range of process tools that allow customers to fully seal and remove their equipment from the inert environment for life or efficiency testing.
Slot Die Coating
Slot-die coating is a highly scalable technique for rapidly depositing thin and uniform films with minimal material waste and low operational cost. Slot-die coating technology is used to deposit a variety of liquid chemistries onto substrates of various materials such as glass, metal, and polymers. This is achieved by precisely metering the process fluid; dispensing it at a controlled rate while the coating die is moved relative to the substrate.
Spin Coating
There are several options, from standard spin coaters to fully integrated solutions with dispensers.
