Full-angle light out-coupling enhancement of quantum dot light-emitting diodes by Mie-scattering micro-lens arrays

High efficiency, high brightness, and long-life quantum dot light-emitting diodes (QLEDs) are crucial for realizing integrated display and lighting applications. However, about 80% of the light is confined inside the device with substrate mode, waveguide mode, and plasma mode, which greatly weakens the brightness, efficiency and lifetime of the device. Here, a quasi-periodic concave template with large area was fabricated through the spontaneous condensation of droplets on the substrate surface. Based on the quasi-periodic template, SiO₂ micro-lens arrays (SiO₂-MLAs) Mie scattering composite structure was fabricated by imprinting on a SiO₂-nanosphere thin film, which significantly improved light out-coupling at full angles with optimized quasi-Lambertian luminescence characteristics. In comparison to the planar QLED with state-of-the-art, the external quantum efficiency (EQE) demonstrated a qualitative improvement (>20%). Accordingly, the EQE, luminance (L), T₅₀ lifetime (reduce to half brightness) of the green QLEDs with SiO₂-MLAs structure have been optimized by 22%, 28%, 31%, and up to 24.21%, 381962.6 cd/m², 111335 h, respectively. This strategy provides valuable insights into mass-producing and utilizing SiO₂-MLA Mie scattering composite structures to boost QLED performance in high-efficiency display and lighting applications.