1 research outputs found
Implications of phosphor coating on the thermal characteristics of phosphor-converted white LEDs
The phosphor layer in phosphor-converted white
Light Emitting Diodes (pcLEDs) affects their optical and thermal
performances. This paper reports the effects of phosphor
thickness and particle concentration on the optical efficiency and
temperature rise on conformal phosphor-coated LED package. It
is observed that a thicker phosphor layer and a higher phosphor
particle concentration will increase the amount of backscattering
and back reflection of light from the phosphor layer. These light
extraction losses not only reduce the optical efficiency of the light
output but also cause heat accumulation in the phosphor layer,
leading to higher LED junction temperature. At 2700 K
correlated colour temperature (CCT), the temperature rise is
observed to increase by as much as 2.6 times as compared to its
blue emitting LED package. However, the self-heating effect can
be reduced through its die-bonding configuration. Structure
function-based thermal evaluation shows heat accumulation in
the phosphor layer and that flip-chip bonding can dissipate the
heat generated in the GaN LED and phosphor layer effectively.
Evidence in this study demonstrates that optical efficiency and
thermal resistance of pcLEDs are dependent on the CCT ratings