Tunable Optical Diffusers Based on the UV/Ozone-Assisted Self-Wrinkling of Thermal-Cured Polymer Films

Tunable optical diffusers have attracted attention because of the rapid development of next generation stretchable optoelectronics and optomechanics applications. Flexible wrinkle structures have the potential to change the light path and tune the diffusion capability, which is beneficial to fabricate optical diffusers. The generation of wrinkles usually depends on an external stimulus, thus resulting in complicated fabricating equipment and processes. In this study, a facile and low-cost method is proposed to fabricate wrinkle structures by the self-wrinkling of thermal-cured polymer for tunable optical diffusers. The uncured polydimethylsiloxane (PDMS) precursors were exposed to UV/ozone to obtain hard silica layers and then crosslinked via heating to induce the wrinkle patterns. The wrinkle structures were demonstrated as strain-dependent tunable optical diffusers and the optical diffusion of transmitted light via the deformable wrinkle structures was studied and adjusted. The incident light isotropically diffused through the sample at the initial state. When the wrinkle structures deformed, it showed a more pronounced isotropic optical diffusion with uniaxial tensile strain. The optical diffusion is anisotropical with a further increase in uniaxial tensile strain. The proposed method of fabricating wrinkles by UV/ozone-assisted self-wrinkling of thermal-cured polymer films is simple and cost-effective, and the obtained structures have potential applications in tunable optical diffusers.