Electrohydrodynamically printed microlens arrays for directional light emission with enhanced intensity from quantum dots

Quantum dots (QDs)—one of the most promising luminescent materials—usually exhibit Lambertian emission characteristics. However, a significant portion of the emitted light is lost due to the large emission angle. To address this issue, we propose a simple approach to achieve highly directional emission with enhanced brightness, where a thin glass layer is added in approximate contact with the printed QD arrays, followed by a microlens array (MLA) electrohydrodynamically printed onto the thin glass surface with coaxial alignment. By leveraging the focusing capability of the MLA, off-axis light rays from QDs are effectively redirected, resulting in highly directional emission and enhanced light intensity (more than 1.5 times increase in brightness) simultaneously.