Yang Jingwen, Duan Zaihua, Zeng Wenxin, Bu Yichen, Tang Xing, Wang Guosheng, Zhou Xin, Dai Qian, Yuan Zhen, Jiang Yadong, Tai Huiling
State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu 611731, China.
Southwest Institute of Technical Physics, 610041 Chengdu, China.
Nanoscale Horiz. 2025 Sep 2. doi: 10.1039/d5nh00495k.
Quantum dots (QDs) have emerged as promising materials for next-generation infrared semiconductors due to their facile solution processing, low-cost, tunable bandgap and superior optoelectronic properties. However, organic long-chain ligands that modify the surface of QDs hinder charge transfer, thus impairing the performance of QD infrared photodetectors. Here, we report a two-step ligand exchange strategy that decouples the native long-chain ligands from the QDs using specific molecules and then attaches the short-chain ligands, resulting in high response for lead-rich lead selenide (PbSe) QD photodetectors. During the layer-by-layer film deposition process, 1-octanethiol is first used for primary ligand exchange to remove stable ligands, followed by 3-mercaptopropionic acid for secondary exchange to ensure thorough passivation of surface defects. The two-step processing PbSe QD photodetector has a responsivity of up to 1.28 A W, a detectivity of 9.65 × 10 Jones and a record high external quantum efficiency of 144.4% at a bias voltage of 0.5 V at 1100 nm. Benefitting from the high performance, the PbSe QD photodetector can be integrated into a pulse monitoring platform, achieving a physiological sign monitoring by capturing real-time pulse signals of human superficial arteries.
量子点（QDs）因其易于溶液处理、低成本、可调节带隙和优异的光电性能，已成为下一代红外半导体的有前途的材料。然而，修饰量子点表面的有机长链配体会阻碍电荷转移，从而损害量子点红外光电探测器的性能。在此，我们报告了一种两步配体交换策略，该策略使用特定分子将天然长链配体与量子点解耦，然后连接短链配体，从而使富含铅的硒化铅（PbSe）量子点光电探测器具有高响应率。在逐层薄膜沉积过程中，首先使用1-辛烷硫醇进行一次配体交换以去除稳定配体，随后使用3-巯基丙酸进行二次交换以确保表面缺陷得到彻底钝化。两步处理的PbSe量子点光电探测器在1100nm波长、0.5V偏置电压下具有高达1.28A/W的响应率、9.65×10琼斯的探测率和创纪录的144.4%的高外量子效率。受益于其高性能，PbSe量子点光电探测器可集成到脉冲监测平台中，通过捕获人体浅表动脉的实时脉冲信号实现生理信号监测。
