Preparation Of Electroluminescent Thin Films By Flexographic Printing And Device Manufacturing

Organic Electroluminescent display(OLED)has the advantages of light weight,wide viewing angle,bright color,fast picture response,low energy consumption and flexible processing,and is considered to be one of the most attractive emerging technologies in the 21 st century.The traditional methods for preparing electroluminescent devices are usually vacuum evaporation or spin coating.The vacuum evaporation method has poor adhesion,poor process repeatability,and serious material waste due to spin coating.Flexographic printing has the characteristics of simple process and low cost.The preparation of OLED devices by flexographic printing is fast and simple,with high material utilization,uniform film thickness,and is suitable for multi-layer film formation.It is the most promising film forming technology for OLED devices.This thesis starts from the preparation of flexographic printing ink and uses organic small molecule material Alq3 as the electroluminescent material to prepare the luminescent layer of OLED devices using flexographic printing method.Based on the performance of Alq3,design and screen the raw materials required for electroluminescent ink.Conduct formula experiments to study the effects of different contents,types of solvents and resins on ink performance.Weights are given based on the importance of ink performance,and regression analysis is conducted to explore the relationship between ink formula and ink performance.The experimental results show that the ink performance is good when using a mixed resin with B-814: BR106:BR113=0.37:0.41:0.22 and a mixed solvent with DMF: chlorobenzene=0.48:0.52.Subjectively evaluate the overall printing quality of the luminescent layer prepared by printing under different printing parameters such as printing speed,printing pressure,and number of anilox roller lines,and test the ink layer thickness and ink thickness variance of the luminescent layer to comprehensively evaluate the quality of the luminescent layer.When the printing pressure is 70N/m and the printing speed is60m/min,the printed luminescent layer can meet the performance requirements.The cathode of the device is prepared by screen printing with different number of screen lines.The square resistance of the cathode is tested.Finally,the cathode with the lowest average resistivity of 13.4ohm/sq is printed with a 200 mesh screen plate.The hole transport layer of the device is prepared by spin coating to make a complete electroluminescent device,and the photoelectric performance of the device is tested.