LEDs (Light Emitting Diodes) are the new competitive solid
lighting devices in the twenty-first century. Compared with the
traditional light sources, LEDs have long lifetime, high reliability
and efficiency. With the ‘‘energy saving, low-carbon economy’’
characteristics, LED is the trend of the times as the ‘‘fourth generation’’
lighting, and it has been widely used in many applications.
However, the LED chip junction temperature is a critical factor
which restricts the LED light source to be used in the automotive
headlight. Currently, the power of modern LED chip for light is
above 1 W, even up to 5 W, and the area of chip is less than
1 mm2
, corresponding to 100 W/cm2 of heat flux, which will result
in high chip junction temperature [1], and the high junction temperature
will greatly lead to the dominant luminescence wavelength
drift, the decline of the optical efficiency, as well as the
degradation lifetime of the phosphor [2]. As a result, the ability
to thermally manage and reduce the chip junction temperature
has become paramount in the overall development of LED automotive
headlight