Oriented Yttrium Strontium Tin Oxide Micro/Nanostructures Induced by Brush Coating for Low-Voltage Liquid Crystal Systems

Abstract

We present a convenient liquid crystal (LC) alignment method using brush hairs. An yttrium strontium tin oxide (YSrSnO) solution was prepared using a sol–gel process, and the one-step brush-coating process integrated film deposition and alignment. X-ray photoelectron spectroscopy confirmed a well-formed YSrSnO film via thermal oxidation. Atomic force microscopy showed oriented micro/nanostructures of the brush-coated film, attributed to shearing stress from brush-hair movements on the coating surface; the directionality was identical to that of the brushed coating, which caused physical surface anisotropy and uniform LC alignment on the YSrSnO layer. Uniform and homogeneous LC alignment was confirmed by polarized optical microscopy and pretilt angle measurements. Thermal stability tests of the LCs showed a suitable thermal budget, and the YSrSnO film showed fine optical transparency. Excellent electro-optical properties were observed in twisted-nematic LC system with remarkable low operating voltage. Thus, we expect brush coating to be a viable next-generation technology for LC systems.

Anisotropic Surface Formation Based on Brush-Coated Nickel-Doped Yttrium Oxide Film for Enhanced Electro-Optical Characteristics in Liquid Crystal Systems

“…The O 1s spectra comprised two sub-peaks, each indicating metal-oxide bonding and oxygen vacancy. These peaks were centered in the ranges of 528.50-530.00 eV and 531.00-531.50 eV, respectively.The peak intensity increases of Ni 2p, Y 3d, and metal-oxide bonding as the curing temperature is increased from 70 to 230 • C indicated that thermal oxidation was well-progressed at the higher curing temperature[21]. This contributed to the formation of a stable NYO film during the curing process, although 70 • C curing was relatively insufficient for producing a stable oxidized NYO film structure, as confirmed by the AFM analysis.…”