Effect of Temperature Gradient on Particle Distribution of Phosphor Film During Curing

The distribution of phosphor particles within the phosphor film is a decisive factor in the performance of LED light-emitting devices. This study utilized both experimental and numerical methods to examine the impact of temperature on the distribution of phosphor particles within a phosphor film and its resultant effect on the luminescence performance during the curing process. The research found that natural convection caused by temperature gradients during the curing process leads to an uneven distribution of particles in the horizontal direction. In addition, it was observed that the viscosity of the organic silicone decreases at the beginning of the process due to an increase in temperature, which exacerbates the natural convection phenomenon. However, as the temperature continues to rise, the cross-linking reaction of the organic silicone intensifies, causing the viscosity to increase more rapidly and ultimately inhibiting natural convection. The final distribution of particles within the phosphor film demonstrated a tendency for concentration and particle size to decrease with the center of the bottom of the film spreading out in all directions. Optical simulations were also performed on the obtained particle distribution, which revealed significant differences in peak intensity at 460 nm and around 560 nm, as well as a nonlinear relationship between temperature variation and correlated color temperature (CCT) and luminescence uniformity.