Printed Polymer‐Stabilized Chiral Nematic Liquid Crystal Privacy Windows

Abstract

In this paper, drop-on-demand (DoD) printing is demonstrated of polymer stabilized chiral nematic liquid crystal (PSCLC) privacy windows that can function in either a conventional mode (scattering to transparent) or reverse mode (transparent to scattering) with the application of an electric field. Inkjet printed droplets of the PSCLC mixture, with diameters of the order of 100-200 μm and sandwiched in LC layer thicknesses of ≈10-15 μm, are characterized in terms of their transmission as a function of the electric field amplitude and the response times for switching into and out of the scattering state. The results show that the printed droplets, and arrays thereof, exhibit similar electro-optical properties to analogous thin-film devices, but with the ability to incorporate bespoke features such as images and decorative patterns. Finally, the electro-optical switching of a printed PSCLC privacy window whereby alphanumeric characters can be made to appear and disappear with the application of an electric field is demonstrated.

Smart Switchable Window with Bistability and Tunability of Transmission

“…The scattering based technologies include polymer dispersed liquid crystals (PDLCs), [16][17][18][19][20][21] polymer stabilized liquid crystal (PSLC), [22][23][24][25][26][27][28][29] and polymerstabilized cholesteric textures (PSCTs). [30][31][32][33][34][35][36][37] In one state under a specific voltage condition, the liquid crystal in the window is in an optically uniform state and is transparent. In another state with a different voltage condition, the liquid crystal is in a multidomain state and is scattering.…”

Drop‐on‐Demand Electrohydrodynamic Printing of Nematic Liquid Crystals

“…[29] Our group have also recently used inkjet printing to fabricate polymer-dispersed LC smart/privacy windows with embedded logos and images. [30,31] Very recently, Coppola et al have DOI: 10.1002/adem.202400245 Electrohydrodynamic (EHD) printing of nematic liquid crystals (LCs) is demonstrated. Miniscule LC droplets, as small as 1 micron, are generated with the EHD printing system and deposited with high precision onto a glass substrate.…”

“…[ 29 ] Our group have also recently used inkjet printing to fabricate polymer‐dispersed LC smart/privacy windows with embedded logos and images. [ 30,31 ] Very recently, Coppola et al have reported the deposition of nematic LC droplets for microlens applications with sizes around 400 μm using a pyro‐electrohydrodynamic technique. [ 32 ]…”