Diffusion films fabricated by phase separation of polymer blend and their application on color uniformity enhancement of LEDs

Based on the phase separation and surface roughening of polymer blend, diffusion films are developed to improve the angular color uniformity (ACU) of light-emitting diodes (LEDs). By controlling the weight ratio of polymethyl methacrylate-polystyrene, diffusion films with different scattering properties can be obtained. Results show that the haze increases with the increasing of microstructure density. The haze can be tuned from 0% to 52% by controlling the material weight ratio. When the film with the highest haze is applied to a LED lamp with a correlated color temperature (CCT) of ~6000 K, the CCT deviation is reduced from 1111k to 532k from −90° to 90°. In conclusion, the diffusion films can be applied as remote films on LED lamps to improve their ACU.