Abstract:
In this presentation, I would like to emphasize how materials science and engineering are playing a key role in realizing innovation, reducing environmental impact and saving energy, using GaN-based light emitting diodes (LEDs) as an example. Portable game machines and cellular/smart phones are very familiar items, especially to young people. It should be stressed that the younger generation can now enjoy full-color portable games and cellular/smart phones because of the emergence of blue LEDs based on InGaN. Today, the applications of blue LEDs are not limited to displays. In combination with phosphors, blue LEDs can act as a white light source and are also used in general lighting. In Japan, about three-quarters of general lighting systems composed of incandescent and fluorescent lamps will have been replaced with LED lamp systems by 2020, by which we can reduce total electricity consumption by 7%, corresponding to a saving of 1 trillion yen per year. AlGaN-based deep-ultraviolet (DUV) LEDs are effective for the sterilization and purification of water. UNICEF reported that 663 million people still lack access to safe drinking water and 2.4 billion people do not use safe sanitation facilities. New water sterilization and purification systems have been commercialized, in which high-power DUV LEDs are installed. Other applications of DUV LEDs include sterilization in sanitation facilities, resins and the curing of inks, detecting forged banknotes, photolithography, and dermatology. I will describe how these material systems were developed and what the researchers who first developed these systems were aiming for. In addition, I will discuss what the next generation of researchers should be doing to achieve future innovations.