Changing the surface characteristics of ITO by plasma cleaning equipment can affect the performance of OLED:
Indium tin oxide (ITO) has the characteristics of high light transmittance and good electrical conductivity. As an anode material, it is widely used in organic electroluminescent devices (OLED). However, the surface work function of ITO and the high hole transport layer NPB in the device There is a high potential barrier between the electron-occupied orbital (HOMO), which leads to the problems of high voltage, low work efficiency, and short life in the driving of the device.

　　 After research, it is found that ITO is treated by oxygen plasma cleaning equipment plasma to greatly improve hole injection and device stability. The use of plasmas of different powers to process the ITO greatly improves the ITO work function and optimizes the performance of the device.
　　 Organic electroluminescent devices (OLED), because of its self-luminous, high brightness, large viewing angle and many other advantages, are favored in the field of display and lighting, and have great application prospects.
　　Since indium tin oxide (ITO) conductive film has good conductivity and high light transmittance in the visible light range, it is widely used in the field of optoelectronics, and it is often used as the anode material of OLED in the field of organic electroluminescence.
In OLED, because ITO can directly contact with organic film, the surface characteristics of TTO, such as surface organic contaminant content, surface resistance, surface roughness and work function, play an important role in the performance of the entire device, changing the surface characteristics of ITO. Can affect the performance of OLED.
　　 The current methods of processing ITO are mainly divided into physical methods and chemical methods. Mainly plasma treatment and polishing treatment, chemical methods mainly include acid-base treatment, oxidant treatment and adding organic and inorganic compounds on the ITO surface.
　　Plasma cleaning equipment plasma treatment is considered to be an effective treatment method. There is a higher potential barrier between the surface work function of ITO and the high electron occupancy orbital (HOMO) of the hole transport layer NPB in the device, resulting in low performance of the device.
　　 The oxygen content on the surface of TTO will directly affect the work function of ITO. An increase in oxygen content will result in a decrease in the Fermi level of ITO and an increase in work function. After ITO is treated with mixed plasma, the surface morphology will change significantly.
　　Analysis of the ITO surface morphology without treatment and the ITO surface morphology after plasma treatment revealed that the average roughness and peak-to-valley distance of the ITO surface were significantly reduced, and the surface particle radius was also reduced a lot. The reduction in average roughness and surface particle radius increases the contact surface between ITO and the organic layer, which is conducive to the adhesion of oxygen atoms.
Plasma cleaning equipment plasma treatment can better improve the surface morphology of ITO. At the same time, it can be seen that the oxygen vacancies on the surface of ITO are significantly increased, and the surface is enriched with a layer of negatively charged oxygen to form an interface dipole layer, which increases the work function of the ITO surface. , Making the hole injection ability of ITO greatly enhanced.
In addition, the surface roughness of ITO is reduced after plasma cleaning equipment treatment, the interface between ITO film and NPB is reduced, hole injection becomes easier, and the electrons injected from the cathode are better recombined to produce excitons. Plasma treatment The device prepared by the anode has high brightness and good quality.