SDK Offers AlGaInP Red LED Chips Optimized for Plant Growth


Showa Denko K.K. (SDK) has started selling samples of aluminum-gallium-indium-phosphide (AlGaInP) LED chips that emit red light with wavelength of 660 nm: the optimum light for accelerating the growth of plants. SDK has achieved output of 11 mW at the drive current of 20 mA by developing a new light-emitting layer. The output figure represents the world’s highest level for 660-nm LED chips as of April 2009, to the best of our knowledge.

In recent years, facilities for growing vegetables in an environment of controlled lighting, temperature, humidity, CO2 concentration and nourishments are attracting attention as they ensure stabilized production regardless of season or place, and realize multiple cropping. Furthermore, they do not need fungicides or insecticides because of the controlled environment. Nearly 30 facilities of this kind are already in operation in Japan.

It has been found that red light with wavelengths of around 660 nm is most effective in increasing the efficiency of photosynthesis, thereby accelerating the growth of plants. Fluorescent lamps, sodium lamps, and conventional red LED lamps are now used at plant growth facilities. However, fluorescent and sodium lamps emit a great deal of light with wavelengths other than around 660 nm, and conventional red LED lamps need to use many chips because of their low output. As a result, these conventional light sources involve problems of energy loss and high costs. Furthermore, the wavelength of conventional AlGaInP LED chips is 650 nm at best, falling short of the ideal wavelength of 660 nm.

In addition to the development of the new 660-nm-light-emitting layer, we have improved shape and arrangement of electrodes as well as the chip surface treatment method. Thus, the external quantum efficiency of LED lamps using the new AlGaInP chips is about three times as high as that of conventional red LED lamps. Compared with the conventional red LED lamps, the new AlGaInP LED lamps reduce electric power consumption by 70% at a given level of brightness, resulting in lower costs and energy consumption at plant growth facilities. Lower heat emission from light sources will also improve the plant growth environment. SDK will step up marketing activities for the new AlGaInP LED chips, while enhancing the chip performance to meet diversified needs from customers.

Under the ongoing Passion Extension, SDK is expanding its ultrabright LED chip operation – consisting of AlGaInP red LED chips and indium-gallium-nitride (InGaN) blue/green LED chips – as a “growth-driver” business. SDK is preferentially allocating its resources to these areas in an effort to further increase its corporate value.

Ultrabright AlGaInP LED lamps

Lamps using the newly developed LED chips