High-Performance Quantum Dot Light-Emitting Diodes With Self-Assembled Bilayer Light Extraction Structure

Quantum dot photodiodes (QLEDs) hold promising potential for next-generation display and lighting devices due to their high emission efficiency, high color purity in the visible region, tunability of emission wavelengths, and low manufacturing costs. However, QLEDs confine a large number of photons inside the device that cannot be utilized, leading to low external quantum efficiency. In this paper, a simple and efficient strategy to construct bilayer light extraction structures is developed based on the self-assembled polystyrene (PS) microspheres embedded in polyvinyl butyral (PVB) film with excellent thermoplasticity. The maximum external quantum efficiency (EQE) of blue-QLED, green-QLED and red-QLED increased from 8.18% to 13.51%, 12.96% to 19.61% and 21.7% to 25%, respectively. It is found that bilayer light extraction structure does not change the light intensity angular distribution of Lambertian emission mode. The bilayer optically coupled structure proposed in this work provides an efficient and stable way for the improvement of QLED performance.