Solution-processed polymer light-emitting diodes (PLEDs) have been widely investigated in display area due to their low-cost and large-scale fabrication. Generally, in order to pattern the device, the electrodes are deposited through a vacuum process such as sputtering or thermal evaporation. In terms of cost, inkjet printing is the most promising alternative to evaporation process because it allows low-material consumption as well as free patterning of the electrodes. However, direct inkjet-printing on the organic layers induces solvent permeation, which causes severe damage to underlying layers. In addition, fine patterns are hard to be obtained because the surface treatment on the functional layers is limited. In this research, we report solution-processed PLEDs with inkjet-printed electrodes. In order to prevent solvent permeation and obtain fine patterns by inkjet printing, we print top electrode on surface-modified polydimethylsiloxane (PDMS) substrate and laminate it on the organic functional layers. A structure of our devices is ITO (anode) / PEDOT :PSS (HIL) / PDY-132 (EML) / PEI (interlayer) / ZnO (EIL) / Ag (cathode). The device with laminated Ag shows a turn-on voltage of 2.7 V at 1 cd/m2 and a current efficiency of 7.8 cd/A at 1000 cd/m2, while the device with evaporated Ag shows 2.4 V and 9.9 cd/A under the same condition. Based on our lamination process, all solution-processed PLEDs are fabricated by replacing ITO to inkjet-printed PEDOT :PSS. Furthermore, passive-matrix application is demonstrated showing the possibilities of all solution-processed display. Detailed fabrication process and experimental results will be discussed at the conference.

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Hyungsoo Yoon, Jongjang Park, Byeongmoon Lee, Changhee Lee, and Yongtaek Hong, "Polymer light-emitting diodes with inkjet-printed electrodes for all solution-processed display application (Conference Presentation)," Proc. SPIE 10942, Advances in Display Technologies IX, 109420C (Presented at SPIE OPTO: February 06, 2019; Published: 8 March 2019); https://doi.org/10.1117/12.2508191.6011724976001.