Smart electro-optical iris diaphragm based on liquid crystal film coating with photoconductive polymer of poly(N-vinylcarbazole)

This study develops a light shutter whose transmittance can be tuned electro-optically. The liquid crystal (LC) film applies the photoconductive material of poly(N-vinylcarbazole) (PVK) based on twisted nematic (TN) liquid crystals (LCs). The hole-transport layer of PVK could reduce the built-in electric field of the LC film under the exposure of UV light. The driving voltage is considerably decreased with the aid of UV light exposure. The repeating optical switching is performed under sunlight illumination with an external bias of electric field $\sim 5\mathrm{V}$. Further, it could be operated under a parallel/cross-polarizer to change the light beam/ring as an iris and used to automatically block the UV light to protect an optical integrated system.