Enhancing the outcoupling efficiency of quantum dot LEDs with internal nano-scattering pattern.

We report an effective method to extract light from quantum-dot light emitting diodes (QLEDs) by embedding an internal nano-scattering pattern structure. We use finite-difference time-domain method to analyze the light extraction efficiency of red QLEDs with periodic, quasi-random, and random internal nano-scattering pattern structures. Our simulation results indicate that random internal nano-scattering pattern can greatly enhance the outcoupling efficiency while keeping wide viewing angle for the red QLED. Similar results are obtained by extending this approach to green and blue QLEDs. With the proposed red, green, and blue QLEDs combination, we achieve 105.1% Rec. 2020 color gamut in CIE 1976 color space. We demonstrate that internal nano-scattering pattern structures are attractive for display applications, especially for enhancing the outcoupling efficiency of blue QLEDs.