Wet Preparation, Characterization Of Silver Cathode And Its Application In PLED

Since 1980s, OLED (Organic Light-emitting Displays) has aroused great interests among researchers and industries due to its outstanding advantages, including active light-emitting, wide viewing angle, high definition, low power consumption, prompt response and good aseismatic performance. As the new generation, OLED presently has many deficiencies, like dry process, which is used to fabricate the cathode, needs not vacuum equipments but also hight costs.In this paper, OLED cathode is acted as the main object. Meanwhile the wet technology has been induced in cathode research. Concretely ITO has been selected as the anode of the device, MEH-PPV as the light-emitting material and metal"Ag"as the cathode material. Silver cathode has been prepared by electroplate and electroless plating process, and its application has been investigated in PLED (polymer organic Light-emitting Displays). The primary contents are described as follows: (1) The character of PLED has been briefly introducedand, and the mechanism of light-emitting, principles of working, the structure and selection of materials and preparation process have been investigated mainly. Finally the present status and prospects in application about PLED have been summarized.(2) It is studied about wet technologies in different systems, including in the organic solution and the inorganic solution. Many influence factors of Ag electroplating layer have been analyzed, such as electrolytical component, current density, mix and additive. An orthogonal experiment has been designed to invest the effect of factors on Ag electroless plating, in this case factors mainly consist ofC AgNO3,C KNaC 4 H 4 O 6 i 4H 2O, temperature and time and so on. Accroding to the experimental parameters, the best resulting condition can be achieved while C AgNO3and C KNaC 4 H 4 O 6 i 4H 2O are controlled at 0.046 g·mL-1, 0.23g·mL-1 at 20℃for 12min. The relationship between time and thickness of silver electroless plating is obtained. The silver plating has also been characterized.(3) By exploying the ellipsometer, the thickness of films between MEH-PPV luminescence layers have been measured, and through these data the influence of MEH-PPV concentration on the thickness of organic films have been achieved. Error analysis has been developed. The resulting conclusion shows that the thickness of MEH-PPV film can reach 100nm wanted when the experimental condition is controlled under the concentration of MEH-PPV solution of 5.5 mg·mL-1 (15μL), the low revolving rate (1800 rpm) for 18s or the high that (3000 rpm) for 30s.(4) The mono-layer polymer OLED has been obtained, which possess the structure of ITO/MEH-PPV/Ag. Its optoelectronical characters have been perfermed, including the fluorescence spectrum, the threshold voltage, life-span time of polymer OLED. Through SEM the surface appearance of OLED before and after its invalidation has been analysed. It is found that the defect on interfaces of devices make vapor and oxygen in air constantly into inside devices, and lead to oxidation and corrosion occurance on the surface of Ag electrode and the age of organic light-emitting layer gradually. Finally these can lead to complete failure of the devices.