Vacuum assembly machine for OLED, DSSC and E-Paper
LCD Manufacturing Equipment
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Organic light emitting displays OLEDs, OLED lights, dye sensitive solar cells DSSC and electronic papers displays EPD or e-papers are different products but have a similar construction principle. They all consist of cover sheets (glass or foil), top and bottom electrodes and in between some liquid or gel-type or soft organic layer. Here is a short, simplified description of these units:
Organic light emitting displays or OLEDs are consisting of a substrate layer with a transparent conductive layer on which two organic semiconductor layers are deposited. One of these organic layers serves as emitter layer, the other one as a conductive, hole transportation layer HTL. The cathode is formed by a metallic layer. The cell is then closed by a cover layer. OLEDs can be used as a display or also simply as a light source (OLED light).
Dye sensitive solar cells DSSC, also called Graetzel cells are thin film solar cells, which are composed of electrodes, a porous high surface titanium dioxide layer, covered with molecular dye on the surface and an aqueos electrolyte. Light is causing the emmission of electrons from the dye. The titanium dioxide transmits the electron to the transparent anode. Via the iodine containing electrolyte the missing electron in the dye is replaced. A current is induced by sun light.
Electronic paper display EPD oder E-papers consist a substrate layer with a thin reflective electrode, lithographic formed pixel walls, and e-ink, a mixture of charged, colored pigments in a liquid, as well as a transparent top electrode and a cover layer. By applying voltage the pigments change position and dark or white pixels are formed. In most cases, flexible substrates are used.
For manufacturing of organic light emitting displays OLEDs, OLED lights, dye sensitive solar cells DSSC and electronic paper displays EPD or e-papers, similar technics can be used for the assembly of the cells. In all cases, you have a lower substrate with a special coating and an upper glass or foil (glass on glass [GoG] / foil on glass [FoG] / foil on foil [FoF]) on which the seal is printed or dispensed already. Then these two sheets have to be assembled under vacuum conditions in order to avoid the inclusion of bubbles into the cell. The two sheets must then be pressed together with a special force in order to make sure, that the distance between substrate and cover sheet is correct. It is important, that the two sheets have enough contact. Pressure should be not too high in order to avoid the squeeze out of the deposition layer or the sealing. Then the sealing has to be hardened in order to establish a stable cell. In many cases, it is an advantage to do hardening while the sheets are still pressed together with an adjusted force.
For LCDs, OLEDs, DSSCs and EPDs or E-papers different assembly machines were developed. Different Layers are laminated in a vacuum. Using these machines, 2D applications, 3D applications as well as roll lamination can be performed. The following picture shows a machine of our partner Shindo Eng. Lab., as well as the tree applications and their specifications.
| 2D Laminator | |||
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| 3D Laminator | |||
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| Roll Laminator | |||
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Vaccum assembly machines are very well suited in order to combine cell assembly with integrated filling of the cell with liquid crystals. This technology is called one drop filling ODF-Technology, because the exact volume of liquid crystals which is necessary to fill the cell is dispensed on the lower glass plate before cell assembly is done. This methode requires extremely precise dispensing technology because too much liquid would cause an overflow of the cell during assembly and pressing, while too less liquid would create bubbles in the LCD. Vaccum assembly is necessary in order to avoid gas bubble inclosure.
The ODF machine from our partner Shindo Eng. Lab. can be combined with the vacuum assembly machines shown above.
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Since ODF-Technology is very precise and therefore used for high-quality Displays, usually assembly procedure is followed by another process step: Smallest bubbles are removed in an autoclave. The micro bubbles are not visible directly after the ODF process, but visible bubbles can be formed after some time. Using an autoclave can ensure, that no visible bubbles will be formed later and therefore increase the quality.
Crystec Technology Trading GmbH can offer equipment from various manufacturers, adapted to your needs and specifications.
