A collaborative effort involving POSTECH and the University of Technology Sydney has yielded an advancement in light source technology. The team used graphene to develop a quantum light emitting diode (Quantum LED) that can precisely emit light using a single atom. This innovative technology generates light by injecting charges into a luminescent material composed of a single atom.
The research team implemented this advanced light source technology using hexagonal boron nitride (hBN), a material known for its ability to stably confine electrons in various atomic defects. Unlike traditional quantum dots, which are composed of hundreds to thousands of atoms, the quantum LED developed by the team exhibits excellent quantum light source characteristics even at room temperature. This breakthrough addresses a significant challenge in the field, as hBN's wide bandgap has historically made it difficult to inject charges electrically, thus hindering the development of LED devices. To overcome this obstacle, the researchers designed a "graphene-hBN-graphene" van der Waals tunneling structure.
Graphene, known for its exceptional electrical properties, plays a crucial role in this structure by rapidly transporting electrons to the interior of hBN. By doping the graphene, the team was able to adjust the energy state of the electrons, thereby maximizing charge injection efficiency. The injected charges were then guided to concentrate on the atomic defects within hBN, resulting in the successful emission of light across a wide range of wavelengths from visible to near-infrared.
The device's ability to operate stably at room temperature marks a significant advancement in the field of quantum technologies. Park Kyu-na, a graduate student at POSTECH and the first author of the paper, emphasized the potential impact of this development, stating, "It will open up new possibilities for the application of next-generation optoelectronic devices and quantum technologies."