Tailoring Particle Distribution for White LEDs With High Color-Uniformity by Selective Curing

The phosphor layer determines optical performances of phosphor-converted white light-emitting diodes (WLEDs). In this letter, a new method to control phosphor particle spatial distributions is proposed. Using blue laser irradiation, phosphor gel was selectively and rapidly cured. In the cured phosphor gel, phosphor particles were fixed. The sedimentation occurred in uncured phosphor gel to form particle patterns. With such a method, a kind of remote-conformal-combined particle distribution was obtained. It has been demonstrated that this phosphor layer configuration can result in the high-angular-color-uniformity LED packaging with different average correlated color temperatures (CCT). Compared to the dispensing coating and settling coating, the presented selective curing coating reduces the angular CCT difference by more than 74% and realizes the minimum CCT difference of 184K in the viewing angles ranging from -70 degrees to 70 degrees. Besides, it has no impact on the light intensity distribution. The Pearson correlation coefficients between the light intensity distributions of the selective curing coating with those of the others are larger than 0.999.