Self-Adaptive Conformal–Remote Phosphor Coating of Phosphor-Converted White Light Emitting Diodes

Angular color uniformity (ACU) and luminous efficiency are the most important optical parameters of white light emitting diodes (WLEDs). In this paper, we proposed conformal-remote phosphor coating structure, including conformal silicone layer and phosphor layer, to improve ACU and luminous efficiency of phosphor-converted WLEDs (pc-WLEDs). Due to the effect of conformal silicone layer, the extraction efficiency of blue light increases and the thermal effect of phosphor layer decreases, which improve the luminous efficiency. In addition, the structure composed by conformal silicone layer and self-adaptive phosphor layer can better match spatial intensity distribution of the chip emitting light. The experimental results have verified that the conformal-remote phosphor coating structure shows very high ACU performance, compared with the conventional phosphor coating and self-adaptive remote phosphor coating structure. Besides, for the self-adaptive conformal-remote phosphor coating, the thickness of silicone layer absolutely had no effect on the luminous efficiency and ACU.