Electrical Control of Quantum Emitters in a Van der Waals Heterostructure

Controlling and manipulating individual quantum systems in solids underpins the growing interest in development of scalable quantum technologies1, 2. Recently, hexagonal boron nitride (hBN) has garnered significant attention in quantum photonic applications due to its ability to host optically stable quantum emitters3-7. However, the large band gap of hBN and the lack of efficient doping inhibits electrical triggering and limits opportunities to study electrical control of emitters. Here, we show an approach to electrically modulate quantum emitters in an hBN–graphene van der Waals heterostructure. We show that quantum emitters in hBN can be reversibly activated and modulated by applying a bias across the device. Notably, a significant number of quantum emitters are intrinsically dark, and become optically active at non-zero voltages. To explain the results, we provide a heuristic electrostatic model of this unique behaviour. Finally, employing these devices we demonstrate a nearly-coherent source with linewidths of ~ 160 MHz. Our results enhance the potential of hBN for tunable solid state quantum emitters for the growing field of quantum information science.

Solution-Processed NiO as a Hole Injection Layer for Stable Quantum Dot Light-Emitting Diodes

In this work, we fabricated quantum dot light-emitting diodes using solution-processed NiO as the hole injection layer to replace the commonly used poly(3,4-ethylenedioxythiophene): poly(styrene-sulfonate) (PEDOT:PSS) layer. We successfully prepared NiO films by spin coating the NiO precursor, then annealing them, and then treating them with UV-ozone under optimized conditions. The best device with the NiO film shows higher current efficiency (25.1 cd/A) than that with the PEDOT:PSS layer (22.3 cd/A). Moreover, the long-term stability of the devices with NiO which is annealed at 500 °C is improved substantially. These results suggest that the NiO layer can be a good alternative for developing stable devices.