What’s the effect of organosilicon doping concentration on the light diffusion films?

Light transmittance and haze are two important indexes to characterize the properties of light diffusion films. The former determines the intensity of light passing through, while the latter determines the uniformity and diffusion effect of line and surface light sources. The transmittance of the PET substrate is 91.13% and the haze is 0.91%. Figure 3-8 (a) shows the variation of the transmittance of the light diffusion film with the doping concentration. Figure 3-8b) shows that the haze varies with the doping concentration. The haze of the doped cylindrical lens light diffusion film increased from 31.67% to 48.87% from 1 wt% to 7 wt%, the haze value increased by 17.2%, and the transmittance increased from 94.82% to 96.92%. For the doped microlens light diffusion film, the haze increased from 80.08% to 83.99%, and the transmittance remained stable. The transmittance of the doped diffusion film increases to a certain extent compared with the PET substrate.

The refractive index of UV cured resin and silicone is lower than that of PET, and the diffusion layer of doped diffusion film. It is equivalent to a layer of low refractive index material, so the transmittance is higher than that of PET substrate. With the increase of doping concentration, the change of transmittance is small, and more particle scattering centers lead to the increase of haze. However, for different micro-nano structures, the haze increases at different rates. The haze growth rate of the diffusion film of the cylindrical lens array is faster, while that of the microlens array is slow. In this paper, the microlens array is honeycomb, with a duty cycle of 0.85 and a diameter of only 35 microns.

Therefore, the light diffusion film of microlens array has a large diffusion range without adding light diffuser.And strong diffusion ability, so the fog value obtained by the test is also larger. Therefore, the addition of low concentration of light diffuser does not have much effect on haze. However, from the diffusion effect photos of the following chapters, we can see that the light diffusion film of the microlens array can not achieve a uniform light diffusion effect when the light diffuser is not doped or the doping concentration is low; for the cylindrical lens array, because its visual angle on the y-axis is compressed, so the increase of doping concentration will increase the diffusion range of the light diffusion film along the y-axis. It can also be seen from the photos of the diffusion effect under different light sources in the following chapters, thus increasing its haze.