Inkjet Printed Polymer Layer on Flexible Substrate for OLED Applications

Abstract

In optoelectronics, inkjet printing (IJP) technology is being developed as an alternative to the traditional techniques for organic materials deposition. In this work, we report the fabrication of organic light-emitting diodes (OLEDs) on the flexible substrate by studying the effect of a surface chemical treatment on the inkjet printed polymer film morphology. The employed piranha treatment increases the substrate surface energy and improves the wettability, thus inducing a decrease in the IJ printed drop thickness. The IJ printed polymer (poly(9,9-dihexyl-9H-fluorene-2,7-diyl)) is the hole-transporting layer (HTL) of a hybrid structure in which the other layers are deposited by vacuum thermal evaporation. Furthermore, in order to determine the effect of the IJ deposition method on the manufactured OLED performances, we compare them to those of devices fabricated using standard technologies. With this aim, OLEDs with the same structure are fabricated by replacing the IJ printed polymer with a spin-coated film employing the same polymer solution. The electrical and optical properties of the electroluminescent devices are investigated and discussed. Despite the lack of thickness uniformity in IJ printed film, which is an intrinsic, technological limit, OLEDs with IJ printed HTL show electro-optical characteristics that are similar to the ones of OLEDs with spin-coated HTL.

Synthesis of Soluble Host Materials for Highly Efficient Red Phosphorescent Organic Light-Emitting Diodes

“…Thus, many research groups have been developing next generation process to overcome those problematic issues by utilizing a solution processes such as spin coating, ink-jet printing, or nozzle printing instead of vacuum thermal evaporation process. [5][6][7] Unfortunately, those processes aforementioned have lots of critical limitations (e.g. short lifetime) which make them hard to be applied to TV application.…”

Organic Light-Emitting Diodes (OLEDs): Materials, Photophysics, and Device Physics

“…Thermal evaporation is the most widely employed method to fabricate efficient, stable OLEDs, even though it has the disadvantages of complexity and high production cost [37]. Solutionprocessing methods such as spin coating [38], ink-jet printing [39], and spray processing [40] have attracted considerable attention for the fabrication of flexible and large-area OLEDs because of their simplicity and low cost.…”

Non-ideal biological layer deposition effects on membrane surface stress based biosensor performance

“…Finally, two conditions in which the biological layer has voids in its center (condition H for void of radius 0.3r and I for void of radius 0.5r) are also examined. The last two conditions may express inhomogeneity due to initial membrane morphology or potentially a coffee-ring effect attributed to the spot deposition [15][16][17][18].…”