High-resolution all-inkjet-printed quantum dot light emitting diodes with reduced intermixing using crosslinkable
Jonghyun Choi1,2, Byeong-Kwon Ju2, Youngwoong Kim3
1Autonomous Manufacturing & Process R&D Department, Korea Institute of Industrial Technology (KITECH), Ansan-si 15588, Republic of Korea.
Nanotechnology
|November 14, 2025
Summary
Researchers developed fully inkjet-printed quantum-dot light-emitting diodes (QLEDs) using a novel photo-crosslinkable polymer. This innovation prevents layer erosion, significantly improving device efficiency and enabling clear, pixelated electroluminescence for advanced display technologies.
Area of Science:
- Materials Science
- Organic Electronics
- Nanotechnology
Background:
- Inkjet printing of multilayer quantum-dot light-emitting diodes (QLEDs) faces challenges in precise droplet deposition and preventing interfacial mixing.
- Intermixing between the hole transport layer (HTL) and emissive layer (EML) causes material erosion, degrading device performance.
- Existing methods struggle to achieve high-resolution pixelation and uniform layer formation in solution-processed QLEDs.
Purpose of the Study:
- To develop a photo-crosslinkable polymer for the hole transport layer (HTL) in inkjet-printed QLEDs.
- To mitigate interfacial mixing and material erosion during the fabrication of high-resolution multilayer QLEDs.
- To enhance the external quantum efficiency (EQE) and electroluminescence (EL) uniformity of inkjet-printed QLEDs.
Main Methods:
- Synthesized a crosslinkable polymer (Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine)] or TFB) with 30 mol% azide-functionalized backbones for photo-crosslinking.
- Fabricated inkjet-printed QLEDs using both pristine and crosslinked TFB HTLs, comparing device performance and characteristics.
- Utilized Fourier-transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and photoelectron spectroscopy in air (PESA) for material and device analysis.
Main Results:
- The crosslinked TFB HTL prevented interfacial mixing and erosion, leading to smooth, continuous CdSe@ZnS emissive layers.
- Devices with crosslinked TFB showed approximately a twofold improvement in external quantum efficiency (EQE), rising from 0.11% to 0.21%.
- Clear pixel-scale electroluminescence (EL) was achieved with the crosslinked TFB, unlike the erosion artifacts observed with pristine TFB.
Conclusions:
- Photo-crosslinking of the TFB HTL is an effective strategy to overcome interfacial mixing issues in inkjet-printed multilayer QLEDs.
- The improved morphology and electronic properties (0.1 eV downward shift in HOMO) of the crosslinked HTL enhance hole injection and exciton confinement.
- This study presents the first laboratory-scale realization of fully inkjet-printed multilayer QLEDs with pixelated substrates, demonstrating a viable fabrication route.
