Tian Fengshou, Zhou Tianhong, Zhang Xuanyu, Chen Rui, Chen Shuming
State Key Laboratory of Quantum Functional Materials, Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
Light Sci Appl. 2025 Aug 19;14(1):279. doi: 10.1038/s41377-025-01972-1.
Colloidal quantum dots (QDs) are promising gain materials for realizing solution-processable, wavelength-tunable and low-cost laser diodes. However, achieving electrically pumped amplified spontaneous emission (ASE) in QDs, a prerequisite for lasing, is hampered by the low net optical gain and low current injection of the diodes. Here we demonstrate electrically pumped and surface-emitting ASE from QDs by electro-thermal-optically co-designing a quantum-dot light-emitting diode (QLED) with high net optical gain and high current injection. By developing a top-emitting cavity featuring a Ag/indium-zinc-oxide (IZO) bottom reflective electrode and a IZO/Ag top semi-transparent electrode, the QD emission is effectively resonated; moreover, not only are the surface plasmon polariton losses induced by the metallic electrodes completely eliminated, but also the optical field can be confined primarily within the QDs, resulting in a reduction in loss and a 2-fold enhancement in gain. As a result, the QLED exhibits surface-emitting ASE with a threshold of 10 μJ cm when pumped by a 100 fs laser at 77 K. By building the QLED directly on a Si heat sink and driving the QLED with an ns-pulsed current source, the Joule heat is effectively dissipated, allowing the QLED to operate stably even at a high current of 2000 A cm. At 153 K and an injection current of 94 A cm, the QLED demonstrates surface-emitting ASE with strong directionality, high intensity and narrow bandwidth. The developed QLED, capable of generating surface-emitting ASE, paves the way for the development of QD based vertical cavity surface-emitting laser diodes.
胶体量子点（QDs）是实现可溶液处理、波长可调谐且低成本激光二极管的有前景的增益材料。然而，在量子点中实现电泵浦放大自发辐射（ASE）（激射的先决条件）受到二极管低净光学增益和低电流注入的阻碍。在此，我们通过对具有高净光学增益和高电流注入的量子点发光二极管（QLED）进行电热光协同设计，展示了来自量子点的电泵浦和表面发射ASE。通过开发一种顶部发射腔，其具有Ag/铟锌氧化物（IZO）底部反射电极和IZO/Ag顶部半透明电极，量子点发射得以有效谐振；此外，不仅完全消除了金属电极引起的表面等离激元极化激元损耗，而且光场可主要限制在量子点内，从而导致损耗降低且增益提高两倍。结果，当在77K下由100 fs激光泵浦时，该QLED表现出阈值为10 μJ cm的表面发射ASE。通过将QLED直接构建在硅散热器上并用纳秒脉冲电流源驱动QLED，焦耳热得以有效消散，使得QLED即使在2000 A cm的高电流下也能稳定运行。在153K和94 A cm的注入电流下，该QLED展示出具有强方向性、高强度和窄带宽的表面发射ASE。所开发的能够产生表面发射ASE的QLED为基于量子点的垂直腔表面发射激光二极管的发展铺平了道路。
