Intrinsically Stretchable OLEDs with a Designed Morphology-Sustainable Layer and Stretchable Metal Cathode

Abstract Recently, the growing desire to conformally integrate electronics with the human body in the form of wearable devices has spurred the need for additional form factors, skin-like softness, and stretchability of organic light-emitting diodes (OLEDs). Traditional intrinsically stretchable OLED (is-OLED) approaches have focused on improving the luminance and stretchability through methods such as blending materials to endow the component layers with stretchability and complex lamination processes. However, the designed microstructure of the blended layer cannot be maintained due to the different orthogonality between the solvents of subsequently coated layers. In addition, the lamination method often leads to degradation of the performance due to delamination induced by formed defects. To overcome these challenges, we developed a sequentially coated is-OLED and confirmed the maintenance of the designed morphologies of each layer and a highly stretchable metallic is-cathode. Our is-OLEDs achieved a maximum total luminance of 3,151 cd m-2 and a total current efficiency of 5.4 cd A-1 (on both the anode and cathode sides). Furthermore, our is-OLEDs exhibited a higher static stretchability of up to 70% than previous work and a notable cyclic stretchability, maintaining 80% of the luminance at 0% strain after 300 stretching cycles under 40% strain. This breakthrough in the fabrication process, coupled with the use of novel stretchable materials, represents a significant step forward in the field of is-OLED technology, potentially leading to a new era of highly durable and efficient soft electronic devices.