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

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.