Using high-performance materials to create a next-generation lighting business
White LED lighting consumes less than one-eighth of the power of an incandescent light bulb, and their lifetime is 40 times longer. In the worldwide lighting market, which is estimated at 10 trillion yen, LEDs are taking at the leading edge. And recently, white LEDs have become an indispensable component for back lighting in ultra-thin LCD TVs.
White LEDs consist of a phosphor, an encapsulant and an LED chip―made from a crystal substrate and an emitting layer. The emitting layer is made from a compound semi-conductor, which converts electric energy into light. The phosphor, dispersed inside the encapsulant, takes the light and produces a variety of colors. Mitsubishi Chemical has developed an LED that, unlike the traditional white LED, produces near-natural white light. The characteristic features of Mitsubishi Chemical's white LEDs are shown below. (This is not an actual comparison, but an outline of the difference in characteristics)
In an effort to produce next-generation white LEDs, we have begun development of a gallium nitride (GaN) violet light emitting chip, not only for the emitting layer but also for the crystal substrate. We have stepped up our commercialization program by sourcing chip technology from Mitsubishi Cable Industries and gaining patent rights for the GaN substrate from Cree (USA). By combining the red, green and blue (RGB) phosphors, we have been able to express colors more freely, and greatly improve light quality.
Among other things, Mitsubishi Chemical also realized the difficult objective of fabricating the worlds first 'm-plane GaN substrate'. The GaN substrate is created by thinly slicing a block of GaN. Unlike traditional methods, it is sliced it from the m-plane. A substrate sliced from the m-plane has improved electrical properties and substantially higher light efficiency. In combination with improvements to the RGB phosphor and other components, we are working to develop LEDs with three times the light efficiency of traditional white LEDs.
Not only are m-plane GaN substrates optimal for use in light emitting devices such as LEDs and semiconductor lasers, their superior power and high frequency means that they have potential for use in electronic devices. A broad range of applications can be expected, in everything from mobile phone transceiver stations to motorized components for vehicles.
The emergence of high-brightness LED chips has stimulated demand for encapsulants and packaging materials that are durable enough to withstand strong light. Mitsubishi Chemical and Mitsubishi Plastics are utilizing their technical expertise to develop highly functional and efficient components that meet these needs. In 2009, Mitsubishi Chemical began production and sales of violet light emitting chips and white LEDs for lighting apparatus. The company is also making an expansion into the US and European markets with the Verbatim brand. Verbatim has built up a global sales network in the recording media field, and looks set to be a driving force behind the sales promotion of LEDs. With the door about to open for our next-generation LED technology, the future has never been brighter.
