41‐2: Invited Paper: Active Matrix Micro‐LED Stretchable Display and Technical Challenges

Abstract

In this paper, we report a 13‐inch active matrix (AM) micro‐LED stretchable display, which can be stretched by up to 20% with a 72 ppi resolution. It features a unique panel de sign, including stretchable interconnects fabricated via the conventional LTPS backplane process and micro‐LED for a light emitting device. This paper will discuss methods for realizing a stretchable panel and practical problems in stretchable display engineering.

High‐resolution active‐matrix micro‐LED stretchable displays

“…When using the panel structure depicted in Figure 2, the main advantage is that only the interconnects need to be stretchable, enabling the use of parts that are difficult to stretch, such as TFTs or micro‐LEDs, in the panel. However, since the designated pixel space contains both rigid and soft areas, the interconnect within the soft area must stretch more than the overall elongation of the pixel 3 . Therefore, reducing the size of the rigid area can help alleviate the strain on the interconnect, but it is not an easy task as a complex pixel driving circuit consisting of multiple TFTs and the minimum space required for micro‐LEDs must be secured within the rigid area.…”

“…However, since the designated pixel space contains both rigid and soft areas, the interconnect within the soft area must stretch more than the overall elongation of the pixel. 3 Therefore, reducing the size of the rigid area can help alleviate the strain on the interconnect, but it is not an easy task as a complex pixel driving circuit consisting of multiple TFTs and the minimum space required for micro-LEDs must be secured within the rigid area. On the other hand, increasing the size of the soft area allows for a design that maximizes the stretchability of the interconnect, but it affects the overall pixel size and panel resolution.…”

“…As the popularity of foldable and rollable products using flexible displays continues to grow, the importance of display form factors is increasing, and research into the next technology-stretchable displaysis becoming more active. In fact, in recent years, several display companies have showcased their future displays using stretchable technology, [1][2][3][4] which offers the possibility of implementing various designs that were previously impossible with existing technologies.…”

Embracing Stretchable “Form Factor‐Free” Displays

“…LG Display also demonstrated a highly stretchable 12-inch 100-pixels per inch (ppi) active-matrix microLED display that can be stretched ~20 percent. 12 According to this graph, the value (product of stretchability and resolution) increases exponentially every year. If these trends persist, it is expected that pushing for further performance improvements through structural design approaches will reach its limits, and a transition to material innovation will be necessary in the near future.…”

“…Prototypes were fabricated based on the materials and methods used to fabricate commercialized flexible displays, and as a result, there is no degradation of the display such as luminance and color volume, even after stretching or deformation. LG Display also demonstrated a highly stretchable 12‐inch 100‐pixels per inch (ppi) active‐matrix microLED display that can be stretched ∼20 percent 12 …”