Nanoantenna-Enhanced Light-Emitting Diodes: Fundamental and Recent Progress

Light-emitting diodes (LEDs) are a promising solution for energy-saving illumination, terminal display technology, and visible light communication. Driven by the vast markets of these emergent applications, the everlasting demand for LED devices is to continuously improve the luminous efficiency and lifetime while minimizing costs. The luminous efficiency of LEDs can be improved from various perspectives including materials, nanofabrication, encapsulation, and other fields, mainly to increase the internal quantum efficiency of the active layer, the light extraction efficiency, the directionality of luminous emission, and the photoluminescence of color-converting layer. A nanoantenna is a delicately designed functional structure with strong capabilities in decay rate enhancement, light regulation, and other unique optical and electrical characteristics, which fully meet the needs of LED emission enhancement. Starting from the mechanism of nanoantennas, how to enhance LEDs by nanoantennas made of metals, dielectrics, and mixtures of both is discussed. By considering some practical cases, the review of the enhanced functionalities of LEDs under the function of nanoantenna are provided. On top of that, the great potential of nanoantennas for the use in micro- and nanostructures, layered structures, and other new LED geometries, and for the active control of LEDs using reprogrammable nanoantennas is also put forward.