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 (4 × 10⁻⁴ S m⁻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 2.8 V. 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%.

基于钙钛矿量子点 (QD) 的发光二极管 (LED) 的外量子效率 (EQE) 超过 25%，且具有窄带发射^1,2，但这些 LED 的工作寿命有限。我们认为，钙钛矿 QD 薄膜中较差的长程有序性（点大小、表面配体密度和点对点堆叠的变化）会抑制载流子注入，从而导致工作稳定性较差，因为在这些 LED 中产生发射所需的偏压较大。在这里，我们报告了一种化学处理方法，以改善钙钛矿量子点薄膜的长程有序：重复量子点单元的衍射强度与对照相比增加了三倍。我们使用协同双配体方法来实现这一目标：用于阴离子交换的富含碘化物的试剂（氢碘化苯胺）和产生强酸的化学反应剂（溴三甲基硅烷），该强酸可原位溶解较小的量子点以调节尺寸并更有效地去除较少的量子点。导电配体可形成致密、均匀且无缺陷的薄膜。这些薄膜表现出高电导率（4 × 10 ^-4  S m ^-1），比对照高2.5倍，是迄今为止钙钛矿量子点中记录的最高电导率。高电导率确保了高效的电荷传输，使红色钙钛矿 QD-LED 能够在 2.8 V 的创纪录低电压下产生 1,000 cd m ^-2的亮度。在此亮度下的 EQE 超过 20%。此外，在EQE超过20%的情况下，该器件的运行稳定性比以前的红色钙钛矿LED好100倍。