Future trends of display technology: micro-LEDs toward transparent, free-form, and near-eye displays

Displays are one of the most indispensable electronic devices used in our daily lives. Over the past decades, display technology has evolved relentlessly, driven by innovation in materials, structures, and manufacturing processes that have enabled higher image quality, larger screen size, slimmer form factor, and novel functionalities. The display market is currently dominated by liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays, but significant investment and research efforts are being directed toward emerging self-emissive display technologies, such as micro-light-emitting diodes (micro-LEDs), as well as unconventional applications such as transparent, deformable, and near-eye displays. This review article begins with a historical background of self-emissive display technology and an overview of the recent advances in organic-, quantum dot-, perovskite-, and micro-LED displays. We then critically review the current state of micro-LED technology, including its size-dependent performance issues, different types of mass transfer technologies, backplane interconnection techniques, methods for detection/repair of defective pixels, and emerging display applications, including transparent, deformable, and virtual and augmented reality (VR/AR) displays.