Design of photonic crystals for light-emitting diodes

Photonic crystals (PCs) can greatly enhance the optoelectronic performance of light-emitting diodes (LEDs) due to their distinctive color, photonic band gap, etc. Therefore, many scholars have conducted extensive research based on the high light extraction efficiency, good monochromaticity, and other excellent optoelectronic properties of PC LEDs. This review discusses the main principles of photonic crystals to improve the optoelectronic performance of LEDs and summarizes 12 structural applications of photonic crystal LEDs, such as PC slabs, Bragg grating, backside reflectors, surface PC, embedded PC, dual PC, PC beads, CPC, PC thin films, LIPC, defective PC, and composite architectures with other materials that boost LED optoelectronic qualities. In summary, it is found that photonic crystals can not only greatly improve the light extraction efficiency of LEDs but also improve other optoelectronic properties such as luminescent color and directional radiation angle, and reduce the manufacturing cost of LEDs. Photonic crystal LEDs are expected to be a strong candidate for future lighting technology. Finally, the prospects and challenges of PC LEDs are summarized.