Ultrathin, Large‐Area, and Multifunctional Polarizer Based on Highly Ordered Carbon Nanotubes Produced by Simple Shear Flow

Abstract Aligning carbon nanotubes (CNTs) with high orientational ordering in a 2D array is essential for realizing optical polarizers with high polarization efficiency over a wide spectral range. Two methods are reported: dispersing CNTs in a polymer matrix followed by stretching, and mechanical stretching of a vertically grown CNT forest and then transferring it onto a substrate. However, neither can realize nanometer‐thin or large polarizers. Herein, a novel approach is demonstrated to construct a large and thin (150 nm) conductive CNT polarizer by achieving liquid crystal (LC) phase of size‐controlled CNTs in chlorosulfonic acid, unidirectional shearing, and then drying. The polarizer exhibits an excellent polarization efficiency of 98.4% for ultraviolet (365 nm) and 96.0% for visible light (550 nm). This performance is maintained even at 400 °C, while the conventional iodine‐type polarizer starts to lose efficiency over 100 °C. The CNT polarizer with high polarization efficiency for UV can replace the costly nano‐patterned wire‐grid polarizers currently used for photoaligning LCs and also its multifunction playing role of polarizer, electrode, and LC alignment is confirmed with switching of LC device. This study provides a new paradigm for realizing ultrathin and large CNT polarizers for broadband applications with outstanding heat resistance.