Long-range order enabled stability in quantum dot light-emitting diodes

• 成果类型: Article
• 署名作者: Wang, Ya-Kun; Wan, Haoyue; Teale, Sam; Grater, Luke; Zhao, Feng; Zhang, Zhongda; Duan, Hong-Wei; Imran, Muhammad; Wang, Sui-Dong; Hoogland, Sjoerd; Liao, Liang-Sheng
• 署名单位: Soochow University - China; University of Toronto; University of Oxford
• 刊物名称: Nature
• ISSN/ISSBN: 0028-3830
• DOI: 10.1038/s41586-024-07363-7
• 发表日期: 2024-05-16
• 页码: 586-+
• 关键词: highly efficient

摘要

Light-emitting diodes (LEDs) based on perovskite quantum dots (QDs) have produced external quantum efficiencies (EQEs) of more than 25% with narrowband emission(1,2), but these LEDs have limited operating lifetimes. We posit that poor long-range ordering in perovskite QD films-variations in dot size, surface ligand density and dot-to-dot stacking-inhibits carrier injection, resulting in inferior operating stability because of the large bias required to produce emission in these LEDs. Here we report a chemical treatment to improve the long-range order of perovskite QD films: the diffraction intensity from the repeating QD units increases three-fold compared with that of controls. We achieve this using a synergistic dual-ligand approach: an iodide-rich agent (aniline hydroiodide) for anion exchange and a chemically reactive agent (bromotrimethylsilane) that produces a strong acid that in situ dissolves smaller QDs to regulate size and more effectively removes less conductive ligands to enable compact, uniform and defect-free films. These films exhibit high conductivity (4x10(-4)Sm(-1)), which is 2.5-fold higher than that of the control, and represents the highest conductivity recorded so far among perovskite QDs. The high conductivity ensures efficient charge transportation, enabling red perovskite QD-LEDs that generate a luminance of 1,000cdm(-2) at a record-low voltage of 2.8V. The EQE at this luminance is more than 20%. Furthermore, the stability of the operating device is 100 times better than previous red perovskite LEDs at EQEs of more than 20%.