Japan develops new light-emitting diodes, making next-generation LED lighting systems possible

　　Quantum dots have experienced an important moment. Last month, Samsung's first QLED TV officially shipped, and production is gradually increasing, which means the promise made 15 years ago seems to have been fulfilled.

　　Currently, researchers at Hiroshima University in Japan have used silicon-based quantum dots to develop a new type of light-emitting diode, promising a new revolution in the history of lighting systems. These researchers have created an inorganic/organic hybrid light-emitting diode that can emit blue-white electroluminescence through quantum dots. This blue-white electroluminescent diode will allow us to invent a new generation of free-lighting and display lighting systems.

　　In a research paper published in Applied Physics Letters, the researchers stated that their quantum dot light-emitting diode only requires a voltage of 6 volts to emit light, and 78% of the effective light emission comes from silicon quantum dots.

To let you know how these figures were calculated: about 6 years ago, the optical efficiency of quantum dots used in state-of-the-art electroluminescent diodes dropped from over 90% to about 15%, because these quantum dots had to be embedded in an organic thin film in order to conduct electricity.

These Japanese researchers also claim that the input and output power densities generated by their LEDs are 280 and 350 times those of previously reported devices, respectively. The reason these quantum dot-based LEDs achieve such high input and output power densities is that the hierarchical structures are continuously optimized in some way, thereby better enabling carrier transfer.

The actual physical size of this LED provides an effective area of 4 square millimeters, which is 40 times that of a typical commercial LED. In addition, this LED is only 0.5 millimeters thick.

Perhaps the most attractive aspect of this research is that this new type of LED is manufactured through a solution-based processing method, which needs to be carried out at room temperature and pressure.

This manufacturing process requires selecting a glass substrate and then pouring onto it some conductive polymer solution and a colloidal silicon quantum solution.

　　Professor and research leader Ken-ichi Saitow of Hiroshima University added: "Quantum dot LEDs have attracted significant attention as the next generation of LEDs. Although their successful application still requires some breakthroughs, the remarkable achievements of quantum dot hybrid LEDs will far exceed our imagination."