Samsung Advanced Institute of Technology

By composing phosphor films in the shape of photonic crystals, the color conversion efficiency of the films can be significantly improved. When the light with photonic band-edge wavelengths is incident on the photonic crystal phosphor film, the excitation photons are resonantly absorbed and thus the emission intensity is enhanced. This study reports on the development of 3D photonic crystal phosphor films based on self-assembled inverse opal structures. The photonic crystal phosphors are constructed using a silk fibroin polymer and red organic fluorescent dyes (l_peak ~ 610 nm) doped into it. The photonic structures are designed through electromagnetic wave simulations and photonic band structure analysis. Fabricated photonic crystal phosphor films are integrated with blue micro-LED chips (l_peak ~ 452 nm), resulting in a color conversion efficiency increase of more than 1.5 times that of bulk phosphor films. Additionally, the experiments are performed using various micro-LED chips with a size of less than 100 micrometers. Overall, our results demonstrate the potential of the photonic crystal phosphor film for future micro-LED-based devices and applications, including displays, lighting, and communication systems.