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They alternate their body color by stretching the skin to enlarge the embedded chromophores.[23] Mechanical modulation is a common practice to control light transmission macroscopically, such as the opening and closing of curtains and blinds. However, mechanical driving of macroscopic units is cumbersome and they must communicate through a mainframe. It is highly desirable to develop a skin-like material/device that can be integrated into building components to change transparency or color. At the microand nanoscales, tuning of the optical properties by mechanical stretching and compressing has been demonstrated from patterned polymer thin films, including micro-[24] and nanopillar arrays [25] on wrinkled poly (dimethylsiloxane)(PDMS), shape memory polymers consisting of periodic microhole arrays [26] and micro-optic components.[27] Many of them have inherent, angle-dependent structural color due to Bragg diffraction from the periodic structures. Typically, the initial state is opaque or colored, attributed to the pre-existing micro-/nanostructures. The windows exhibit increased transmission upon stretching due to the reduction of surface roughness, thus less scattering. However, the roughness of the materials and the resulting light scattering cannot be completely eliminated. Therefore, it is difficult to achieve high transparency with> 90% transmittance in the visible region either before or after mechanical modulation. Here, we prepared a composite film consisting of a thin layer of quasi-amorphous array of silica nanoparticles (NPs) embedded in bulk elastomeric PDMS. Importantly, it was highly transparent (> 90% transmittance in …