Updated: May 11, 2026

Planar and Three-Dimensional Printing of Conductive Inks
Published on: December 9, 2011
Joong-Yeon Cho1, Kyeong-Jae Byeon, Jin-Seung Kim
1Department of Materials Science and Engineering, Korea University, Sungbuk-gu, Seoul, South Korea.
This study introduces a new way to make brighter red LEDs using direct printing and dry etching. Traditional methods use wet etching to roughen the LED surface, but this leads to uneven shapes that reduce light output. The researchers developed a technique that creates precise cone-shaped structures, improving light extraction without affecting electrical performance. Their method increased light output by 12% compared to traditional LEDs and worked well even after packaging. This could lead to better-performing LEDs for lighting and displays.
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Area of Science:
Background:
AlGaInP red LEDs are widely used in lighting and display applications. Their performance depends heavily on light extraction efficiency. Traditional methods rely on wet etching to roughen surfaces and improve light output. However, wet etching has limitations in pattern height and shape due to the crystal structure of AlGaInP. This results in tiled cone shapes that reduce effectiveness. Prior research has shown that surface roughening can enhance light extraction, but the shape and uniformity of the etched structures remain a challenge. No prior work had resolved the issue of achieving a high-aspect-ratio cone shape using alternative methods. This gap motivated the exploration of dry etching combined with direct printing. The goal was to overcome the limitations of wet etching while maintaining electrical performance. This study introduces a novel fabrication approach to improve LED efficiency.
Purpose Of The Study:
The aim of this work was to enhance the light extraction efficiency of AlGaInP red LEDs. Current methods using wet etching produce structures with limited height and irregular shapes. This reduces the effectiveness of light extraction. The researchers sought to develop a new fabrication technique that could create more uniform and effective surface patterns. They focused on using direct printing and dry etching to overcome the limitations of traditional methods. The study aimed to compare the performance of LEDs fabricated with this new technique to those made using wet etching. The researchers also wanted to ensure that the new method did not degrade electrical performance. Their goal was to achieve a more efficient and reliable LED design.
The method increased light output power by 12% compared to wet-etched LEDs without electrical degradation.
Dry etching creates high-aspect-ratio cone shapes, while wet etching leads to tiled structures that reduce efficiency.
The patterning process does not degrade electrical characteristics, ensuring stable operation after fabrication.
The cone shape enhances light extraction efficiency by optimizing surface roughness and structure.
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Main Methods:
The researchers used direct printing and dry etching to fabricate the LED structures. Direct printing allowed for precise patterning of the LED surface. Dry etching was used to create high-aspect-ratio cone shapes. This process avoided the limitations of wet etching, which leads to tiled cone structures. The team compared the new LED design to traditional wet-etched LEDs. They measured light output power and electrical performance before and after packaging. The fabrication process was optimized to ensure consistent cone shapes. The study evaluated the impact of surface patterning on light extraction efficiency.
Main Results:
The LEDs fabricated using direct printing and dry etching showed a 12% increase in light output power compared to wet-etched LEDs. The new method produced a perfectly cone-shaped pattern with high aspect ratio. This structure improved light extraction efficiency without affecting electrical performance. The enhanced output power was maintained even after the packaging process. The results suggest that the new fabrication technique is effective for improving LED performance. The patterning did not lead to any degradation in electrical characteristics. The LED structures remained stable and functional after fabrication. The findings indicate that direct printing is a viable alternative to wet etching for LED surface patterning.
Conclusions:
The authors concluded that direct printing combined with dry etching improves LED performance. The new method overcomes the limitations of wet etching by producing high-aspect-ratio cone shapes. These structures enhance light extraction efficiency without electrical degradation. The 12% increase in light output power supports the effectiveness of the new fabrication approach. The results were consistent even after the packaging process. The study suggests that direct printing is a promising technique for LED fabrication. The authors propose that this method can be applied to other LED designs to improve efficiency. The findings provide a foundation for further development of high-brightness LEDs.
Yes, the 12% increase in output power was maintained even after the packaging process.
They propose applying direct printing to other LED designs to improve brightness and efficiency.