近日，苏州大学功能纳米与软物质研究院的廖良生及其研究团队取得一项新进展。经过不懈努力，他们发现长程有序能够实现量子点发光二极管的稳定性。相关研究成果已于2024年5月8日在国际权威学术期刊《自然》上发表。

该研究团队成功报道了一种化学处理方法，显著提升了钙钛矿QD（量子点）薄膜的长程有序性。相比对照组，来自重复QD单元的衍射强度显著增加了三倍。这一成果得益于研究人员采用的一种协同双配体方法。他们首先使用富碘剂（氢碘苯胺）进行阴离子交换，接着利用化学反应剂（溴三甲基硅烷）产生强酸，这种强酸能够原位溶解较小的量子点，以调节尺寸，并有效去除不导电的配体，从而实现致密、均匀和无缺陷的薄膜。这些薄膜具有高导电性(4×10^-4Sm^-1)，比对照组高2.5倍，是迄今为止钙钛矿量子点中记录的最高导电性。高导电性确保了高效的电荷传输，使红色钙钛矿QD-LEDs在2.8V的创纪录低电压下产生1000 cd  m^-2的亮度。更值得一提的是，此亮度下的EQE大于20%。

据悉，基于钙钛矿量子点(QDs)的发光二极管LEDs)在窄带发射下产生了超过25%的外部量子效率(EQEs)，但这些LEDs的工作寿命有限。人们假设钙钛矿QD薄膜中较差的长程有序——点尺寸、表面配体密度和点对点堆叠的变化——抑制了载流子注入，导致运行稳定性较差，因为在这些LEDs中产生发射所需的大偏置。

附：英文原文

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

Author: 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

Issue&Volume: 2024-05-08

Abstract: Light-emitting diodes (LEDs) based on perovskite quantum dots (QDs) have produced external quantum efficiencies (EQEs) of more than 25% with narrowband emission, 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 1,000 cd m^-2 at a record-low voltage of 2.8V. The EQE at this luminance is more than 20%.

DOI: 10.1038/s41586-024-07363-7

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