Domestic researchers have implemented QD-OLED panel technology that continuously stacks an OLED light-emitting layer and a quantum dot (QD) color-converting layer on a single substrate using an industrial inkjet printing process. It is evaluated as an achievement that reduces the process complexity of the existing two-substrate bonding method and increases the potential for next-generation display industrialization.

The Korea Electronics and Telecommunications Research Institute (ETRI) announced on the 3rd that it has developed integrated technology for a 'single-substrate stacked QD-OLED' in collaboration with Kosan Tech Co., Ltd. and Duksan Neolux Co., Ltd.

The results of this study were published in the international academic journal *Chemical Engineering Journal* in the field of chemical engineering.

Currently, commercial QD-OLEDs generally have a two-substrate structure in which a blue OLED light-emitting substrate and a QD color-converting substrate are fabricated separately and then bonded.

This method has limitations in that the addition of a filler layer and a bonding process increases panel thickness and manufacturing complexity.

The research team applied a structure in which a thin-film encapsulation (TFE) layer is formed on a blue OLED light source, and a black pixel definition layer (Black PDL) and a QD color conversion layer are directly stacked on top of it.

Through this, the possibility of a process that can continuously fabricate two layers on a single substrate without a separate QD substrate was confirmed.

The core of this technology lies in the integration of three technological elements.

Duksan Neolux Co., Ltd. has developed a high aspect ratio Black PDL material that can be stably formed even in low-temperature processes below 100℃, thereby minimizing the thermal impact on the underlying OLED device.

Gosan Tech Co., Ltd. provided process control technology capable of precisely dispensing QD ink into fine pixel areas using a multi-nozzle-based inkjet head.

ETRI optimized the panel manufacturing process by integrating these materials, components, and equipment technologies.

The research team implemented a total of 184,800 subpixels on a 6-inch substrate and achieved a pixel density of 141 ppi.

This is a 65-inch 8K TV-class displayThe research team explained that it is similar to the level required for.

It is evaluated that the potential for industrialization is high, given that the process was verified at the 6-inch panel level rather than stopping at unit device experiments.

Dr. Kwon Byung-hwa of ETRI’s Realistic Display Research Lab stated, “Having secured a full-cycle technology foundation extending from materials to processes and panel manufacturing, we expect this to contribute to securing a leading position in the future market for ultra-high-resolution mixed reality (MR) and extended reality (XR) displays.”

This research was conducted with support from the Ministry of Trade, Industry and Energy and the Korea Institute for Industrial Technology Evaluation and Management (KEIT)’s Industrial Technology Innovation Project ‘Development of Inkjet Printing Materials, Components, and Equipment for Flexible QD-OLEDs’ and ETRI’s Basic Project ‘Research on Ultra-Realistic Spatial Device Technology’.