Incandescent lamps, HID lamps, LED lamp light sources, and other illuminants are used in automobile headlights, which have become more energy-efficient and compact. While headlights that use LEDs as light sources are increasingly common, the light intensity of a single LED light source is insufficient, requiring headlights to use as many as 50 LEDs. Accordingly, these headlights are more expensive than conventional lights.

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Studies on increasing the efficiency and amount of light are focusing on LD illuminants, which have begun to see adoption in luxury automobiles. As LD illuminants emit coherent light with high light density, reports have noted concerns that the headlights could cause eye damage. In response, blue laser light is irradiated to phosphor powder (doped fluorescent substance (Ce:YAG), in monocrystals) to convert wavelength in order to convert the light to safe incoherent light of reduced density. However, Ce:YAG monocrystal is so expensive that adoption in popular vehicles is difficult.

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Accordingly, the combination of a composite of quantum-dot silica-based inorganic materials (light conversion materials that are inexpensive, highly efficient, and possess outstanding light durability) and blue LDs in common use will enable the provision of safe, durable, and affordable illuminants.