Toyoda Gosei began research on blue LEDs in 1986 under the guidance of Professors Isamu Akasaki and Hiroshi Amano, who were awarded the Nobel Prize in Physics in 2014. We were the first in the world to successfully develop blue LEDs in 1991 and began mass producing them in 1995. Blue LEDs use gallium nitride and UV-C LEDs use aluminum nitride, both of which are main materials in nitride semiconductors. Since the principle of forming chips on a sapphire substrate is the same, the knowledge and technical abilities that Toyoda Gosei cultivated over many years in the development and production of blue LEDs is applied in the development of UV-C LEDs.

UV-C LEDs differ from blue LEDs in that the lens material diffuses light. Normally resin or glass is used for lenses, but because the transmittance of UV-C LEDs is low a special lens with high transparency called quartz glass is used. However, quartz glass has the property of absorbing light itself, making inefficient extraction of light an issue. Electricity is changed into greater amounts of light and as the light output is raised the sterilization effect becomes higher. Therefore, we are concentrating on development to improve the light extraction efficiency.
In 2021, the Ministry of the Environment adopted the development of highly efficient, long-life UV-C LEDs as a demonstration project. Toyoda Gosei is working together with Meijo University, Nagoya University, Tohoku University, University of Tokyo, and WOTA Corporation in an industry-government-academia project. Professor Hiroshi Amano, with whom Toyoda Gosei worked in the past on the research and development of blue LEDs, is also participating. We look forward eagerly to project results that will help bring forward the day mercury lamps can be replaced.

Toyoda Gosei is also dedicated to product development using UV-C LEDs. One such product is water purification units. To effectively purify water with UV-C, the way the water flows (fluidity) and the light irradiation methods are key aspects. We applied the fluid analysis technology we cultivated in the plastic molding of automotive parts, lengthened the water retention time inside the unit, and studied the structural design and light reflectance for the effective irradiation of UV-C light. Since current UV-C LEDs produce much heat, heat dissipation was also considered and a structure that cools LEDs with water passing through the inside was adopted.
As a result, both a high disinfecting performance that can disinfect eight liters of water per minute and a compact size that fits in the palm of your hand, at one-third the size of previous products, were achieved. These units can be installed in limited spaces, and are used in Eco-cute heat pump water heaters with a disinfecting function.
In April 2024, we developed UV-C LEDs that achieved light output at the 200 milliwatt level on a single chip. The LED device structure was improved, the amount of light that could be extracted was increased about four-fold, and the sterilization capacity was raised three-fold. Sample sales have begun in Japan and internationally, and applications are being expanded with use in water, air and more. We will expand the fields of use of UV-C LEDs, including future replacement of mercury lamps, and contribute to more hygienic, secure, and safe living.