Inorganic light-emitting diode displays using micro-transfer printing

Large quantities of microscopic red, green, and blue light-emitting diodes (LEDs) made of crystalline inorganic semiconductor materials micro-transfer printed in large quantities onto rigid or flexible substrates form monochrome and color displays having a wide range of sizes and interesting properties. Transfer-printed micro-LED displays promise excellent environmental robustness, brightness, spatial resolution, and efficiency. Passive-matrix and active-matrix inorganic LED displays were constructed, operated, and their attributes measured. Tests demonstrate that inorganic micro-LED displays have outstanding color, viewing angle, and transparency. Yield improvement techniques include redundancy, physical repair, and electronic correction. Micro-transfer printing enables revolutionary manufacturing strategies in which microscale LEDs are first assembled into miniaturized micro-system light engines, and then micro-transfer printed and interconnected directly to metallized large-format panels. This paper reviews micro-transfer printing technology for micro-LED displays.