Highly Efficient Color Conversion of 3D Photonic Crystal Phosphor Films for Micro‐Light‐Emitting Diode Applications

Abstract

The color conversion efficiency of phosphor films can be significantly improved by producing them in the shape of photonic crystals (PhCs). When light with photonic band‐edge wavelengths is incident on a PhCs phosphor film, the excitation photons are resonantly absorbed, enhancing the emission intensity. This study develops three‐dimensional PhC phosphor films based on self‐assembled inverse opal structures. PhC phosphors are constructed using a silk fibroin polymer and red organic fluorescent dyes (λpeak ≈ 610 nm) doped into it. The photonic structures are designed using electromagnetic wave simulations and photonic band structure analyses. The fabricated PhC phosphor films are integrated with blue micro‐light‐emitting diode (micro‐LED) chips (λpeak ≈ 452 nm), resulting in a color conversion efficiency increase of more than 1.5 times that of bulk phosphor films. Additionally, experiments are performed using various micro‐LED chips with a size of less than 100 μm. Overall, the results of this study demonstrate the potential of PhC phosphor films in future micro‐LED‐based devices and applications, including displays and communication systems.