The device comprises at least one power light emitting diode light source 102 and other means 142 able to constitute one or more heat sources of such a nature as to affect the thermal environment of the light emitting diode light source. In accordance with the invention, the device also comprises a support piece 100 formed at least partially from a material based on anisotropic graphite supporting the light emitting diode light source and opposing an effect of the other means on the thermal environment of the light emitting diode light source. According to other characteristics, the support piece comprises at least one thermal dissipation heat sink 105 and the device can comprise a fan able to force a circulation of air through the heat sink.