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This study investigated the improvement of the electro-optical properties of a liquid crystal (LC) cell fabricated through brush coating using graphene oxide (GO) doping. The physical deformation of the surface was analyzed using atomic force microscopy. The size of the groove increased as the GO dopant concentration increased, but the direction of the groove along the brush direction was maintained. X-ray photoelectron spectroscopy analysis confirmed that the number of C–C and O–Sn bonds increased as the GO concentration increased. Since the van der Waals force on the surface increases as the number of O–metal bonds increases, we were able to determine why the anchoring energy of the LC alignment layer increased. This was confirmed by residual DC voltage and anchoring energy measurements that were later performed. As the GO concentration increased, the width of the hysteresis curve decreased, indicating that the residual DC voltage decreased. Additionally, the 15% GO-doped sample exhibited a significant increase in its anchoring energy up to 1.34 × 10−3 J/m2, which is similar to that of rubbed polyimide. It also secured a high level of electro-optical properties and demonstrated potential as a next-generation thin-film display despite being produced via a simple brush-coating process. [ABSTRACT FROM AUTHOR]

In this study, we describe the characterization and applicability of the liquid crystal (LC) system of brush-coated indium strontium oxide (InSrO) film. To achieve this aim, the film curing temperature was adjusted and the surface morphology was examined using atomic force microscopy and corresponding line profile data. In particular, we revealed a nano/microgroove anisotropic surface structure on the film after curing at 230°C, which was derived from the shear stress generated during movement of the wet brush hairs and subsequent active thermal oxidation of InSrO. In addition, x-ray photoelectron spectroscopy confirmed the presence of a well-formed InSrO film on the substrate. The film also exhibited hydrophilic properties at higher curing temperatures along with an amorphous structure. The InSrO film represented high optical transmittance to the LC system, and we confirmed the uniform and homogeneous LC alignment state using polarized optical microscopy and pre-tilt angle analyses. The oriented anisotropic film structure induced the alignment of LCs on the surface through geometric constraints. The InSrO film also exhibited advanced electro-optical performance with a fast response time and low operating voltage compared to the polyimide layer conventionally used in LC systems. From these results, we expect that brush-coated InSrO film will be a good alternative in advanced LC systems. [ABSTRACT FROM AUTHOR]

This paper introduces anisotropic nickel yttrium oxide (NYO) film formed by the brush coating technique. X-ray photoelectron spectroscopy confirmed well-formed NYO film after the curing process, and the morphology of the surface was investigated using atomic force microscopy. The shear stress driven from brush hair movements caused the nano/micro-grooved anisotropic surface structure of NYO. This anisotropic surface induced uniform liquid crystal (LC) alignment on the surface, which was confirmed by pre-tilt angle analysis and polarized optical microscopy. The contact angle measurements revealed an increase in hydrophilicity at higher temperature curing, which contributed to homogenous LC alignment. The NYO film achieved good optical transmittance and thermal stability as an LC alignment layer. In addition, the film demonstrated good electro-optical properties, stable switching, and significantly enhanced operating voltage performance in a twisted-nematic LC system. Therefore, we expect that this brush coating method can be applied to various inorganic materials to achieve an advanced LC alignment layer. [ABSTRACT FROM AUTHOR]