The key technology in the process of OLED preparation

A, indium tin oxide ( ITO) Substrate pretreatment

( 1) ITO ITO surface roughness has been widely used in commercial display panel manufacturing, it has high transmission rate, low resistivity and switching function, etc. In general, using the method of rf sputtering ( 射频溅射) Made of ITO, vulnerable to poor process control factors lead to uneven surface, thus producing substances or bumps on the surface of the tip. The other high temperature calcine and recrystallization process also produces about 10 ~ 30 nm surface layer. The uneven between layers of fine grained path will provide hole which is formed by the direct at the cathode, and these complex path will increase the leakage current. Generally there are three ways to solve the influence of the surface? U a is to increase the thickness of the hole injection layer and hole transport layer to reduce leakage current, this method is used to PLED and thick cavity OLED ( ~ 200海里) 。 The second is to handle the ITO glass, make the surface smooth. Three is to use other coating methods make better surface roughness.

　　( 2) ITO work function increases when the hole by ITO injection HIL, large potential difference will produce revided energy barrier, making hole injection not easily, so how to reduce the ITO/HIL interface of potential energy difference became the focus of the ITO pretreatment. Generally we use the O2 - Increase oxygen saturation in the ITO Plasma way, in order to reach the goal of increasing work function. ITO the O2 - After the Plasma treatment of work function can be increased from 4. 8 ev and on up to 5. 2 ev, and the work function of the HIL is extremely close.

add auxiliary electrode, due to the current OLED for components, when external line is too long, or go to the external circuit will cause severe voltage gradient, make the real component of the voltage drop in OLED, reduce the panel luminous intensity. Due to the large ITO resistance ( 10欧姆/平方) , the outside of the unnecessary power consumption, increasing the auxiliary electrode in order to reduce the voltage gradient is a shortcut to the luminous efficiency, reduces the driving voltage. Chromium ( CrChromium) Metal is the most commonly used as auxiliary electrode material, it has beautiful of environmental factors on stability and selectivity of etching fluid have larger, etc. But its resistance value in the membrane layer for 100 nm for 2 ohm/square, in some applications is still too large, so in the same thickness with low resistance of aluminum ( AlAluminum) Metals ( 0. 2欧姆/平方) As auxiliary electrode another better choice. Aluminum metal, however, highly active also make it have problems of reliability as a result, much of the laminated auxiliary metal has been put forward, such as Cr/Al/Cr or Mo/Al/Mo, however, such a process increase the complexity and cost, so the choice of auxiliary electrode materials become one of the focus of OLED technology. Second, the cathode process

in the high resolution of OLED panel, will be small and isolation between the cathode, commonly used methods for mushroom configuration method ( 蘑菇结构方法) , this process is similar to printing technology development of negative photoresist technology. In a negative light resistance enhancement process, many process variation factor will affect the quality of the cathode and the yield. For example, the body resistance, dielectric constant, high resolution, high Tg and low critical dimensions ( CD) Losses and other organic layer and ITO or appropriate adhesive interface, etc. Three, encapsulation,

the improvement of the life cycle of the water absorbing material generally OLED are susceptible to moisture and oxygen around the impact. Is divided into two main types of water vapour is a through the external environment penetration into the component, the other is in OLED technology is absorbed by each layer material moisture. In order to reduce the moisture into components or excluded by the process of adsorption of water vapour, generally the most commonly used material for absorbing water material ( Desiccant) 。 Desiccant to use chemical adsorption and physical adsorption ways to capture the free movement of water molecules, in order to achieve the goal of removing moisture within the component.

2 encapsulation process technology and equipment the development of the process as shown in figure 4, in order to put Desiccant in flat and smooth plate and substrate bonding, in vacuum environment or the cavity is filled with inert gas, such as nitrogen. It is worth noting that how to make the cover plate and the substrate, the two parts process cohesion more efficiently, reduce packaging costs and to reduce packaging time so as to achieve the best production rate, has become a packaging technology and equipment technology development of the three main goals.

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