近日，苏州大学的廖良生&王亚坤及其研究团队取得一项新进展。他们提出了面向高效近红外钙钛矿量子点LED的全覆盖液态双齿配体策略。相关研究成果已于2025年1月7日在国际知名学术期刊《光：科学与应用》上发表。

在这项工作中，研究人员开发了一种化学处理策略，以消除界面猝灭位点并实现高载流子利用率。研究人员采用了一种双齿液态试剂（甲脒硫氰酸盐，FASCN），其与量子点结合紧密，能够有效抑制配体损失和界面猝灭位点的形成。经FASCN处理的薄膜表现出比原始油酸配体高出四倍的结合能。

此外，短链配体（碳链长度<3）使得处理后的薄膜导电性提高了八倍。同时，FASCN的液态特性避免了高极性溶剂的使用，保证了更好的钝化效果。高导电性确保了电荷的有效传输，使得基于钙钛矿量子点的近红外LED在776纳米波长下实现了创纪录的低电压1.6伏。此外，经处理的LED的最高外量子效率（EQE）约为23%，这是对照组的两倍，也是目前报道的基于钙钛矿量子点的近红外LED中的最高值。

据悉，钙钛矿量子点（PQDs）在发光二极管（LEDs）领域展现出巨大潜力。然而，采用钙钛矿量子点的近红外（NIR）LEDs的外部量子效率相较于可见光范围发光的钙钛矿量子点LEDs要低。这一问题的根源在于钙钛矿量子点的动态表面——配体损失和离子向界面位点的迁移会形成猝灭中心，从而导致势阱辅助复合和载流子损失。

附：英文原文

Title: Liquid bidentate ligand for full ligand coverage towards efficient near-infrared perovskite quantum dot LEDs

Author: Liu, Zong-Shuo, Wang, Ye, Zhao, Feng, Li, Hua-Hui, Liu, Wei-Zhi, Shen, Wan-Shan, Duan, Hong-Wei, Wang, Ya-Kun, Liao, Liang-Sheng

Issue&Volume: 2025-01-07

Abstract: Perovskite quantum dots (PQDs) show promise in light-emitting diodes (LEDs). However, near-infrared (NIR) LEDs employing PQDs exhibit inferior external quantum efficiency related to the PQD emitting in the visible range. One fundamental issue arises from the PQDs dynamic surface: the ligand loss and ions migration to the interfacial sites serve as quenching centers, resulting in trap-assisted recombination and carrier loss. In this work, we developed a chemical treatment strategy to eliminate the interface quenching sites and achieve high carrier utilization. We employ a bidentate and liquid agent (Formamidine thiocyanate, FASCN) with tight binding to suppress the ligand loss and the formation of interfacial quenching sites: the FASCN-treated films exhibit fourfold higher binding energy than the original oleate ligands. Furthermore, the short ligands (carbon chain <3) enable the treated films to show eightfold higher conductivity; and the liquid characteristics of FASCN avoid the use of high polar solvents and guarantee better passivation. The high conductivity ensures efficient charge transportation, enabling PQD-based NIR-LEDs to have a record-low voltage of 1.6V at 776nm. Furthermore, the champion EQE of the treated LEDs is ~23%: this is twofold higher than the control, and represents the highest among reported PQD-based NIR-LEDs.

DOI: 10.1038/s41377-024-01704-x

Source: https://www.nature.com/articles/s41377-024-01704-x