Distortion‐Free Stretchable Light‐Emitting Diodes via Imperceptible Microwrinkles
Sujin Jeong, Hyungsoo Yoon, Byeongmoon Lee, Seunghwan Lee, Yongtaek Hong
Abstract
Abstract Stretchable organic light‐emitting diodes (OLEDs) have been considered as a promising technology for next‐generation free‐form and wearable displays. However, an approach to ensure both high device performance and high resolution has not yet been suggested. While introducing a wrinkled structure in the active pixel areas is a decent method, the formation of out‐of‐plane macroscopic wrinkles having a wavelength of a few hundred µm has caused distortion in the shape of the pixel, which is a critical drawback for a matrix‐configured display demanding a sharp pixel definition. Herein, microwrinkled OLEDs are fabricated to define a distortion‐free pixel by direct deposition of OLEDs on biaxially prestretched elastomeric substrate, being feasible by a low‐temperature‐based solution process. The total thickness of the device can be significantly reduced up to 350 nm, producing the imperceptible microwrinkles having a wavelength under 20 µm. The microwrinkled OLEDs show a luminance over 8000 cd m −2 and maximum current efficiency of 7.76 cd A −1 , which is comparable to the device without wrinkled structure. Finally, a stretchable 4 × 4 OLED pixel array with a microwrinkled structure is demonstrated showing sharply defined square‐patterned emission, proving the potential in the future high‐resolution stretchable display.