Enhanced Photon Recycling Enables Efficient Perovskite Light‐Emitting Diodes

• Published in: Advanced functional materials Vol. 34; no. 49
• Main Authors: Cho, Changsoon, Sun, Yuqi, You, Jeonghwan, Cui, Lin‐Song, Greenham, Neil C.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.12.2024
• Subjects: Efficiency; electroluminescence; indium tin oxide; Indium tin oxides; Light emitting diodes; Near infrared radiation; near‐infrared perovskite light‐emitting diodes; optical modeling; parasitic absorption; Perovskites; Photoluminescence; photon recycling; Photons; Quantum efficiency; Upper bounds
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202411556

Perovskite light‐emitting diodes (PeLEDs) have recently experienced rapid growth in performance. While photon recycling, which involves the reemission of reabsorbed light, significantly boosts efficiency, PeLED structures are typically based on classical design principles, often overlooking photon recycling. Here, a practical strategy to maximize the benefit of the photon recycling effect in PeLEDs is demonstrated. Parasitic absorption in electrodes represents a significant loss that impedes the efficient recycling of photons in trapped modes. The design strategy is verified by improving the average electroluminescence quantum efficiencies from 19.5% to 22.0% in near‐infrared PeLEDs with thinner indium tin oxide (ITO) electrodes, ultimately achieving a champion efficiency of 23.9%. The effect of photon recycling is visualized by transient photoluminescence mapping. It is quantified computationally that the additional efficiency coming from photon recycling is doubled from 2.3% to 4.8% in the device by suppressing the relative loss in ITO from 39% to 13%. The strategies raise the theoretical upper bound efficiency of PeLEDs with a gold top electrode from 27% to 37% by boosting the photon recycling effect. Optical design rules for perovskite light‐emitting diodes (PeLEDs) are investigated. The reduction of parasitic absorption loss in transparent electrodes doubles the benefit of photon recycling in near‐infrared PeLEDs, enhancing the external quantum efficiency to 23.9%. While current PeLED efficiencies are already near the saturation point, such an optical strategy can raise the theoretical maximum efficiency from 27% to 37%.