P‐111: Black Photoresist Bank for Inkjet‐Printed Quantum Dot Light‐Emitting Diodes

Abstract

We demonstrated a bank structure for inkjet-printed quantum dot light-emitting diodes (QLEDs) fabricated through photolithography process using black photoresist (B-PR). The B-PR banks have low surface energy (13 mJ m -2 ), resulting in well confined quantum dot (QD) ink inside the pixel area. Based on the B-PR bank structure, we demonstrated a QLED with 0.20 % of external quantum efficiency.

Inkjet‐printed multi‐color arrays based on eco‐friendly quantum dot light emitting diodes with tailored hole transport layer

“…To realize the small size of RGB pixel dimension for next-generation display with self-emissive QLED using inkjet printing technology, we fabricated bank arrays by a conventional photolithography. 15 Photoresist bank arrays were fabricated on ITO substrates before PEDOT: PSS coating, as pixel-defined substrates (see Appendix A.3, 20 μm vertical gaps and 40 μm horizontal gaps between pixels with the pixel size of 60 μm  160 μm, Figures S11-S13). With bank structures, the effectiveness of tailored double HTL structures in inkjet-printed QLEDs was validated using green InP/ZnSeS QDs ink with CHB/octane (2%).…”

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

“…Further perspectives are also discussed with respect to the production of single‐inkjet‐printed light‐emitting devices of μ‐OLEDs as well as μ‐QD‐LEDs (or nano‐LEDs). [ 34,37,46,47 ] To the best of our knowledge, this is the first time the simplest single‐inkjet process is reported for high‐performance microinlaid OLED pixel arrays using a phase‐separable material combination.…”

“…In relation to these applications, a number of studies of inkjet printing have sought to realize uniform pixel formation and patterning for solution-processable light-emitting diodes (LEDs) that utilize not only organic semiconducting materials [10][11][12][22][23][24][25][26][27][28][29][30][31][32][33] but also quantum dots (QDs). [34][35][36][37] As recent examples, by the precise deposition of droplets using the drop-on-demand inkjetprinting technique, thin red-(R), green-(G), blue-(B), and/or white-emitting material layer (EML) pixels were fabricated for highperformance light-emitting pixel arrays of organic LEDs (OLEDs) as well as QD LEDs (QD-LEDs). [29][30][31][32][33][34] Nevertheless, in many of these examples, prior to the inkjetprinting deposition step, the substrates were usually prepatterned with insulating polymeric walls of acrylate or polyimide materials surrounding each pixel site in the form of a bank-like structure, into which the ink droplets can be held, [29][30][31][32][33][34] except for several examples without such prepatterned structures.…”

“…[34][35][36][37] As recent examples, by the precise deposition of droplets using the drop-on-demand inkjetprinting technique, thin red-(R), green-(G), blue-(B), and/or white-emitting material layer (EML) pixels were fabricated for highperformance light-emitting pixel arrays of organic LEDs (OLEDs) as well as QD LEDs (QD-LEDs). [29][30][31][32][33][34] Nevertheless, in many of these examples, prior to the inkjetprinting deposition step, the substrates were usually prepatterned with insulating polymeric walls of acrylate or polyimide materials surrounding each pixel site in the form of a bank-like structure, into which the ink droplets can be held, [29][30][31][32][33][34] except for several examples without such prepatterned structures. [12,[22][23][24] Such a prepatterning process, normally including complex photolithographic procedures, has the potential to contaminate the surface of the substrate, unavoidably deteriorating device performance capabilities.…”

“…Further perspectives are also discussed with respect to the production of single-inkjet-printed light-emitting devices of μ-OLEDs as well as μ-QD-LEDs (or nano-LEDs). [34,37,46,47] To the best of our knowledge, this is the first time the simplest single-inkjet process is reported for high-performance microinlaid OLED pixel arrays using a phase-separable material combination. The single-inkjet-printing technique investigated in this work is based on the use of a material combination of laterally phaseseparable functional compounds.…”