Intense Light Treatment of Inkjet-Printed Metal Oxide Hole Injection Layer for Quantum Dot Light-Emitting Diodes

초록

Inkjet printing is a key technology for realizing electroluminescent quantum displays owing to its high material utilization efficiency and excellent scalability in patterning processes. Nevertheless, despite continuous advances in quantum dot synthesis and device architecture, QLED devices in which all layers are fabricated exclusively via inkjet printing remain extremely rare. This limitation originates from insufficient process compatibility among functional materials and the narrow solvent selection window required to achieve uniform thin-film formation. Herein, these challenges are addressed by introducing an intense pulsed light (IPL) process as an alternative to conventional thermal annealing, enabling the use of materials that require high-temperature treatment without damaging the pattern definition layer. Furthermore, the physicochemical properties of solvents were systematically analyzed to optimize processing conditions for uniform thin-film formation via inkjet printing. Consequently, compared with PEDOT:PSS-based devices, which exhibit limited control over thin-film morphology, devices employing IPL-treated MoOX achieved an approximately sixfold enhancement in external quantum efficiency (EQE) while successfully realizing a pixelated, fully inkjet-printed QLED device with a resolution of 200 ppi. These results demonstrate that the proposed approach effectively expands the material selection window for inkjet-printed QLED displays and presents a promising processing strategy for next-generation printed display applications.

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