Micro light-emitting diode (micro-LED) will play an important role in the future generation of smart displays. They are found very attractive in many applications, such as maskless lithography, biosensor, augmented reality (AR)/mixed reality etc, at the same time. A monitor that can fulfill saturated color rendering, high display resolution, and fast response time is highly desirable, and the micro-LED-based technology could be our best chance to meet these requirements. At present, semiconductor-based red, green and blue micro-LED chips and color-conversion enhanced micro-LEDs are the major contenders for full-color high-resolution displays. Both technologies need revolutionary ways to perfect the material qualities, fabricate the device, and assemble the individual parts into a system. In this roadmap, we will highlight the current status and challenges of micro-LED-related issues and discuss the possible advances in science and technology that can stand up to the challenges. The innovation in epitaxy, such as the tunnel junction, the direct epitaxy and nitride-based quantum wells for red and ultraviolet, can provide critical solutions to the micro-LED performance in various aspects. The quantum scale structure, like nanowires or nanorods, can be crucial for the scaling of the devices. Meanwhile, the color conversion method, which uses colloidal quantum dot as the active material, can provide a hassle-free way to assemble a large micro-LED array and emphasis the full-color demonstration via colloidal quantum dot. These quantum dots can be patterned by porous structure, inkjet, or photo-sensitive resin. In addition to the micro-LED devices, the peripheral components or technologies are equally important. Microchip transfer and repair, heterogeneous integration with the electronics, and the novel 2D material cannot be ignored, or the overall display module will be very power-consuming. The AR is one of the potential customers for micro-LED displays, and the user experience so far is limited due to the lack of a truly qualified display. Our analysis showed the micro-LED is on the way to addressing and solving the current problems, such as high loss optical coupling and narrow field of view. All these efforts are channeled to achieve an efficient display with all ideal qualities that meet our most stringent viewing requirements, and we expect it to become an indispensable part of our daily life.

Mechanical metamaterials possess unusual mechanical properties that cannot be found in nature. Auxetic metamaterials have negative Poisson's ratios and tend to expand in a direction perpendicular to the axial extension direction. When the Poisson's ratio of a display circuit board is forced to be −1 by adopting an auxetic metamaterial, a display can be stretchable without image distortion, and this display is called a meta‐display in this study. The critical obstacles to implementing a stretchable display are large stretchability, high deformation uniformity, and low image distortion. The meta‐display overcomes these obstacles by incorporating micro‐LEDs and a kirigami‐based auxetic circuit board. An auxetic meta‐display with a stretchability of 24.5%, Poisson's ratio of −1, and no image distortion under uniaxial stretching is demonstrated. Finally, the roll transfer process enabled the scaling‐up of a 3‐inch meta‐display attachable to surfaces with non‐zero Gaussian curvatures. This conformity to the non‐zero Gaussian curvature helps realize biomedical applications such as wearable display, phototherapy, and skincare.

DLG has a superior electromechanical stretchability compared to SLG owing to strain relaxationviasliding of graphene layers over one another.