A mechanism of the penetration limit for producing holes in poly(4-vinyl phenol) films by inkjet etching

Light‐Emitting Microinlaid Spots Produced through Lateral Phase Separation by Means of Simple Single‐Inkjet Printing

“…The mechanism of this inkjet‐etching process for via‐hole formation is commonly known as the coffee‐ring effect due to the microfluid flows in a sessile droplet. [ 38–43 ] Such an inkjet‐based selective etching process has several advantages over conventional complex photolithographic etching processes and can therefore allow a simple maskless, photoresist‐free, and cost‐saving patterning process feasible for creating open via‐holes in electronic devices, biochips, and micropatterned cell arrays. [ 38–43 ] In particular, based on these advantages, inkjet‐etched open via‐holes were also used as bank‐like walls not only for thin‐film transistors [ 38,41 ] but also for inkjet‐printed micro‐OLEDs (μ‐OLEDs), [ 42,43 ] which were produced by the subsequent inkjet printing of light‐emitting materials into the inkjet‐etched open via‐holes.…”

“…[ 38–43 ] Such an inkjet‐based selective etching process has several advantages over conventional complex photolithographic etching processes and can therefore allow a simple maskless, photoresist‐free, and cost‐saving patterning process feasible for creating open via‐holes in electronic devices, biochips, and micropatterned cell arrays. [ 38–43 ] In particular, based on these advantages, inkjet‐etched open via‐holes were also used as bank‐like walls not only for thin‐film transistors [ 38,41 ] but also for inkjet‐printed micro‐OLEDs (μ‐OLEDs), [ 42,43 ] which were produced by the subsequent inkjet printing of light‐emitting materials into the inkjet‐etched open via‐holes. During these subsequent inkjet‐printing processes, however, several critical pixel defects can arise due to misalignments between the inkjet‐etched open via‐holes and the subsequent inkjet‐printed material arrays.…”

“…Meanwhile, inkjet printing has also been developed as a subtractive tool capable of site selectively removing small areas of predeposited layers, that is, inkjet etching. [38][39][40][41][42][43] In the inkjetetching process, a solvent in the droplet locally dissolves a predeposited polymer layer, resulting in a crater-shaped via-hole that forms due to the redeposition of the dissolved polymer on the contact line at the edge of the droplet. The mechanism of this inkjet-etching process for via-hole formation is commonly known as the coffee-ring effect due to the microfluid flows in a sessile droplet.…”

“…The mechanism of this inkjet-etching process for via-hole formation is commonly known as the coffee-ring effect due to the microfluid flows in a sessile droplet. [38][39][40][41][42][43] Such an inkjet-based selective etching process has several advantages over conventional complex photolithographic etching processes and can therefore allow a simple maskless, photoresist-free, and cost-saving patterning process feasible for creating open via-holes in electronic devices, biochips, and micropatterned cell arrays. [38][39][40][41][42][43] In particular, based DOI: 10.1002/smsc.202200017 High-performance solution-processable light-emitting diodes (LEDs) attract much research interest due to the very high complexity of conventional vacuumprocessed LEDs.…”

“…After inkjet printing, the solvent in the sessile droplet begins to dissolve and etch the polymer layer. Then, the dissolved polymer is delivered to the edge of the droplet (the contact line of the droplet) by the convective and/or capillary flows of the solvent and consequently redeposited at the edge of the droplet, [7,8,[38][39][40][41][42][43]48] eventually constructing a hole-like vacancy in the polymer layer (upper panel of Figure 1a). Meanwhile, simultaneously, as the solvent in the sessile droplet evaporates, only the phase-separated functional solute molecules begin to recirculate from the edge to center of the droplet via Marangoni flows.…”