P‐73: High‐Resolution Color Patterning of an OLED Device via Capillary‐Induced Ink Filling and a Sublimation Transfer Process

Abstract

We studied capillary‐induced ink transfer technology in order to achieve a breakthrough in relation to the fabrication of a high‐resolution color patterning for OLED display. In this approach, the selective surface treatment of a donor substrate, capillary‐induced ink filling, and a solidified ink sublimation transfer technique are important processes. We investigated the characteristics of ink as it was filled into microchannels and the sublimation transfer characteristics of EML films in accordance with the volume fraction of 1,2‐dichlorobenznene (oDCB) (oDCB/T) and the spin speeds. Through a selective surface treatment, red EML ink was successfully deposited into the microchannels using a conventional spin‐coating process. With the optimized ink filling properties and the sublimation transfer process, we fabricated phosphorescent OLED devices with striped EML patterns. Finally, we demonstrated that a red EML layer can be patterned with a width of 14 µm and pitch of 36.1 µm (700 ppi).

Solution and Evaporation Hybrid Approach to Enhance the Stability and Pattern Resolution Characteristics of Organic Light-Emitting Diodes

“…Previously, we reported that a red-emitting layer (EML) can be patterned with a width of 14 μm and a pitch of 36.1 μm by capillary-induced ink-filling and sublimation transfer processes, respectively. 28 However, due to the insufficient performance of the selective surface treatment, it is difficult to fill EML ink onto the microchannels accurately; this lead to arouse many defects and difficulties to enhance pattern resolutions. In this work, we greatly enhanced the pattern resolutions and verified the mechanisms of ink filling and IPL evaporation for the highresolution OLEDs through the newly developed selective surface treatment.…”

“…Previously, we reported that a red-emitting layer (EML) can be patterned with a width of 14 μm and a pitch of 36.1 μm by capillary-induced ink-filling and sublimation transfer processes, respectively . However, due to the insufficient performance of the selective surface treatment, it is difficult to fill EML ink onto the microchannels accurately; this lead to arouse many defects and difficulties to enhance pattern resolutions.…”

High-Resolution Patterning of Organic Emitting-Layer by Using Inkjet Printing and Sublimation Transfer Process

“…Figure 1a provides a sequential schematic diagram of the patterning process in our experiment through which inkjet printing was grafted onto the sublimation transfer process. In previous research [21,22,31], high-resolution patterns with a pitch of about 14 µm were successfully obtained by spin-coating and sublimation transfer processes. To use inkjet printing to implement the ultra-high resolution pattern, the donor substrate was designed with a 9 µm pitch and a 3 µm width of microchannel; actually fabricated, the pitch and the microchannel width were approximately 9 µm and 4 µm, respectively.…”

Solid-State Lighting Using Side-by-Side White Phosphorescent Organic Light-Emitting Diodes

“…Current methods for S×S organic device patterning include vacuum deposition through fine metal shadow masks, direct patterning via organic vapor-jet printing, solution processing using ink-jet printing or microchannels, film transfer via laser-induced thermal imaging, and postdeposition processing via chemical lift-off. − A somewhat less complex and damage-free method that can achieve photolithographic resolution is mechanical peel-off, which has recently been demonstrated for patterning organic photovoltaics and perovskite light-emitting devices. , In this work, we demonstrate two-color, S×S WOLEDs deposited via vacuum thermal evaporation and subsequently patterned using mechanically peeled-off films. This method allows for multilayer patterning with micron-scale resolution while avoiding precise alignment of shadow masks, or exposing the individual color-emitting stripes to destructive solvents used in conventional photolithography.…”

“…The use of white organic light-emitting diodes (WOLEDs) for solid-state lighting has increased significantly in recent years as a result of their desirable form factors, high efficiencies, long operational lifetimes, color versatility, and other features. − Illumination sources utilizing organic emitters offer diffuse light that can cover large areas and are flexible and transparent. , Materials and device design further enable a range of aesthetic qualities, including a high color-rendering index (CRI) and color temperature tunability, without sacrificing efficiency. − Previous work using a stacked WOLED geometry consisting of multiple emissive layers has achieved efficient white light and a CRI as high as 89. , Stacked WOLEDs comprising individually contacted red, green, and blue, or blue and yellow sub-elements allow for independent tuning of both emission color and intensity, although this architecture presents challenges in contacting metal electrodes within the organic stack. − Color tunability has also been achieved in devices where emission color is dependent on applied voltage. , To generate the desired colors, high voltage or alternating current may be required. A side-by-side (S×S) geometry, in which two or three separately energized monochromatic emitter stripes are horizontally positioned relative to one another, enables color tunability under normal device operating conditions, while also affording the possibility of 100% internal efficiency when triplet-controlled emitting molecules are employed in the individual color elements. − …”