Enhancing light extraction from perovskite light-emitting diodes via lens design

Perovskite light-emitting diodes (PeLEDs) have made significant progress in recent years, achieving external quantum efficiencies (EQEs) exceeding 20%, on par with the latest organic LEDs (OLEDs). 20%, comparable to those of the state-of-the-art organic LEDs (OLEDs). However, the EQEs of PeLEDs have approached conventional limits due to poor light extraction efficiencies (LEEs) similar to the case of OLEDs. Here, we propose a simple yet effective approach to improve LEEs by extracting the substrate modes in PeLEDs through lens design. The maximum EQEs of the control devices are boosted from 13.5% to 26.8% with a 6-mm-diameter hemispherical lens. Further, we investigate the LEE enhancement with different diameters ranging from 10 μm to 10 mm, and we show that, unlike OLEDs, the LEEs of PeLEDs exhibit very limited improvements using a standard microlens array. Instead, the LEE enhancement becomes more pronounced as the lens diameter increases to above ~2 mm.