Application of inkjet printing in the large area display of organic light-emitting diode

As the interaction media between human beings and electronic devices, display technology has become more and more important in our daily life with the development of modern information technology such as big data technology and artificial intelligence, which also brings the huge demands on the market of large area display. Active organic light-emitting diode (OLED) is one of the most competitive candidates for the next-generation display, fulfilling the demand of vivid color, wide view angle, flexible stretchability and high contrast. Thus, OLED devices have already been widely applied in small-size displays such as smart watches, smart phones, tablet computers and automobile monitor and so on. However, currently most commercialized OLED devices are still fabricated by high-cost methods, greatly hindering their application in large area display. For example, in the commercial large area display, only white OLED technology has been practically employed regardless of its high fabrication cost which is the reason of its less sharing market occupancy. White OLED technique faces some difficulties that can hardly be solved perfectly for adopting thermal deposition process, such as poor utilization of organic materials, expensive deposition facilities and low product yields, etc. The technique of QD-OLED is another alternative method for large area display, which is the upcoming scheme Samsung promotes firmly, but it has been repeatedly delayed in the mass production because there are still some unconquered barriers in materials and manufacturing processes. According to the announcement of Samsung display company, in the next half year of 2021, the commodity of QD-OLED will be appeared finally, but it could not be sold in large quantities, which will be with high price exceeding expectation of consumer. Therefore, including TV, phone and monitor, the retail price of OLED products is much higher than that of liquid crystal display (LCD) all the time, impeding the commercial application of large area OLED. With the advantages of effective material utilization, low cost and convenient fabrication of large area panel, inkjet printing is relatively suitable for the manufacture of large area OLED display, which is the crucial developing technique to the display companies and researching institutes. Except the immaturity of industrial inkjet machine and process, the efficiency and stability of OLED based on inkjet printing can’t satisfy the requirements of commercialized application. Consequently, it is significant that OLED based on inkjet printing with high efficiency and long lifetime is realized and marketed by improving ink materials, devices and processes to achieve low price and outstanding performance. In this paper, starting with descripting the current status of large area OLED display, we briefly introduce the recent progresses of inkjet printing OLED and relevant materials and devices, as well as their applications in large area display. Finally, we present our ideas about the future developing direction of new display of OLED based on inkjet printing technology.