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

Title：

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

Authors：

Ya-Kun Wang^1#Haoyue Wan^2#, Sam Teale^2,3, Luke Grater², Feng Zhao¹, Zhongda Zhang¹, Hong-Wei Duan¹, Muhammad Imran², Sui-Dong Wang¹, Sjoerd Hoogland²& Liang-Sheng Liao¹*

Institutions：

¹Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, People’s Republic of China.

²Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada.

³Clarendon Laboratory, University of Oxford, Oxford, United Kingdom.

Abstract：

Light-emitting diodes (LEDs) based on perovskite quantum dots (QDs) have produced external quantum efficiencies (EQEs) of more than 25% with narrowband emission1,2, 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 (4×10−4Sm−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%.

IF：

64.8

Link：

https://www.nature.com/articles/s41586-024-07363-7