Surface modifying method for improving surface power function of indium tin oxide transparent conductive film

Abstract

The invention belongs to the technical filed of conductive thin films, in particular relates to a surface modifying method for improving the surface power function of an indium tin oxide transparent conductive film. The surface modifying method comprises the following steps: a large volume of plasma, containing oxygen, chlorine, or fluorine strong electric negative elements, is generated in a vacuum chamber in a radio frequency or microwave discharge excitation way; sheet glass coated with an indium tin oxide (ITO) thin film is placed on a metal substrate bench which is dipped in the plasma; high voltage negative pulses are applied on the substrate bench, thus forming a negative voltage sheath layer between the ITO thin film and the plasma; oxygen ions are accelerated by an electric field to move toward the surface of the ITO thin film in the sheath layer; and high-energy oxygen ions are injected to the surface of the ITO thin film and reserved in a surface layer of the ITO thin film, so that O / (Sn+In) atom proportion of the surface of the ITO thin film is increased, and then the surface power function of the ITO thin film is improved. The ITO thin film modified by the surface modifying method provided by the invention is applied as an anode of an organic light emitting diode (OLED), in this way, the drive voltage of a component is reduced greatly, the current stability of the component is improved, the light efficiency and brightness are enhanced, and the service life of the component is prolonged.

Description

technical field [0001] The invention belongs to the technical field of conductive thin films, and in particular relates to a method for modifying the surface of an indium tin oxide transparent conductive film. Background technique [0002] Indium tin oxide (ITO) transparent conductive film has both excellent conductivity and transparency, and is widely used as the anode of OLEDs and the hole-collecting electrode of solar cells, as well as the light-transmitting window. However, the surface work function of the ITO transparent conductive film prepared by various methods is about 1eV lower than the highest electron-occupied orbital (hereinafter referred to as HOMO) of the hole transport layer (hereinafter referred to as HTL) of the OLED, and holes must overcome the 1eV barrier height to inject into OLED The interior of the device is difficult, and a high voltage needs to be applied to the OLED device, and the hole injection efficiency is not high, resulting in low luminous int...

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Problems solved by technology

In essence, ultraviolet light and ozone only play the role of cleaning the organic impurities on the ITO surface, and cannot substantially improve the work function of the ITO surface, and the effect is very limited; in theory, acid cleaning can change the polarity of the ITO surface to a certain extent and improve the surface work, but the experimental The effect is not significant, and some acid treatment results are even counterproductive; while the oxygen-containing plasma bath can clean the organic impurities on the ITO surface, it increases the terminal oxygen content on the ITO surface and enhances the surface polarization, thereby improving the ITO surface work function to a limited extent. Such as the Chinese invention patent CN200510004470.6 and the Japanese patent JP2006345377, however, the increase of the terminal oxygen content of the ITO surface through the oxygen-containing plasma bath is restricted by the surface chemical balance, and the improvement space is very limited, and it is uncontrollable. , the ITO surface treatment effect degrades in a very short time

Even if the OLED device is prepared immediately after the treatment, the result is still very unsatisfactory, and the oxygen atoms that are not firmly bonded on the ITO surface will penetrate into the organic material, destroying the photoelectric properties of the organic material, especially the organic light-emitting material. Fluorescence properties, since oxygen is the strongest fluorescence quencher

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