WAVELENGTH CONVERTED LIGHT EMITTING DEVICE

摘要

In a method according to possible embodiments of the invention, for a predetermined amount of light produced by a light emitting diode and converted by a phosphor layer comprising a host material and a dopant, and for a predetermined maximum reduction in efficiency of the phosphor at increasing excitation density, a maximum dopant concentration of the phosphor layer is selected. Accordingly, a structure is defined comprising : a light source emitting light having a first peak wavelength; and a phosphor disposed in a path of light emitted by the light source, the phosphor for absorbing light emitted by the light source and emitting light having a second peak wavelength, wherein the phosphor comprises: a host material and a dopant; a first region having a first dopant concentration; and a second region having a second dopant concentration; wherein the second dopant concentration is less than the first dopant concentration; and the phosphor is arranged such that light emitted by the light source reaches the second region before the first region. The first and second regions may be formed by the core and shell of phosphor particles, respectively.