Inkjet Printing Technique and Its Application in Organic Light Emitting Diodes

Development of printable and flexible Organic Light Emitting Diodes (OLEDs) might provide a path to the large and global production of displays in the lighting market. A lot of research is being done in many fields like materials, equipment, processing methods, etc. to make this technology cheaper and more efficient. This article unveils the inkjet printing technique and its challenges for printed, cost-effective OLEDs. Firstly, to understand the inkjet printing mechanism, various rheological parameters involved in inkjet printing and ink formulation have been discussed. Then, the interaction between the ink and the substrates were introduced, and solutions to avoid the commonly observed "coffee-ring" structure were reviewed. A summary of the recent progress in inkjet printing of polymers and small molecules in OLED devices was also given and other techniques such as aerosol and electrohydrodynamic jet printing, which open up alternative depositing method were discussed. Finally, the challenges involved in the printing of large area displays on an industrial scale were presented.