OLED Inkjet Printing
The OLED inkjet printing uses solvents to melt OLED organic materials and subsequently prints
materials on the surface of substrates to form R (red), G (green), and B (blue) organic
light-emitting layers.
Inkjet Printing Polymer Materials
Due to the greater molecular weight of polymers, solution processing was mainly used to form
films, such as spin coating or printing, while inkjet printing technology has proven to be the most
efficient method for preparing light-emitting polymer solutions. In 1990, Richard Friend et al.
discovered the electroluminescence properties of polymers in Cavendish Laboratory at the
University of Cambridge and invented the polymer light-emitting diode (PLED). Since then, PLED
display has attracted great attention and demonstrated considerable potential for manufacturing
next-generation flat-panel displays.
Inkjet Printing of Small Molecule Materials
At present, the efficiency (6-8cd/A) and the lifetime of polymer light-emitting devices (PLEDs) are
generally low. Small-molecule light-emitting devices (SM-OLEDs) possess obvious performance
advantages, such as higher efficiency (84cd/A) and a longer lifespan. Although PLEDs possess
limitations in their application use, multilayer phosphorescent SM-OLEDs fabricated through the
thermal evaporation process can achieve higher efficiency to overcome certain limitations.
In one study, Xia et al. created thin films of these traditional thermally evaporated small-molecule
materials by inkjet printing and prepared phosphorescent small-molecule light-emitting devices
with better performance. As a result, obtaining high-quality functional thin films remains
necessary for fabricating efficient and long-life devices, while available small molecule materials
have poor film-forming properties. During the drying process of the liquid film on the substrate, it
is easy to form a discontinuous film. In this regard, there are two primary methods to improve
the film-forming properties of small molecules. First, the molecular volume can be