Pseudo-4D Printing of Microbubble Arrays in Quantum Dot-Doped Polymer Films for Effective Light Extraction

Quantum dots (QDs) with excellent optical properties are rapidly emerging as promising materials for the construction of photonic devices and systems. However, the light generated within QD-based devices always suffers from limited light out-coupling efficiency due to photon trapping effects caused by successive total internal reflection and waveguide losses at the edge. This study introduces a pseudo-4D printing strategy to construct microbubble arrays to tackle light trapping in QDs films. By direct writing of QD-doped polymers, microbubbles can be gradually generated in printed QD films through thermal-induced vaporization. Through precise control of the temperature and internal stress, the size distribution of microbubble arrays within the printed film can be effectively adjusted. These embedded microbubbles act as effective light scatterers, significantly suppressing waveguide modes propagating toward the edges. The resulting films achieved a remarkable non-edge out-coupling efficiency of 79.55%, significantly outperforming conventional films without microbubble arrays (25.11%).