Fabrication of TiO2-Embedded Polyimide Layer with High Transmittance and Improved Reliability for Liquid Crystal Displays

Abstract

Construction of liquid crystal (LC) alignment by introducing polyimide (PI) to indium tin oxide (ITO) electrodes is one of the main methods to realize high-resolution images in liquid crystal displays (LCD). However, the loss of transmittance caused by the difference in refractive index between ITO and PI leads to direct degradation of LCD performance. Thus, we herein fabricated a functional hybrid PI alignment layer that reduces the difference in refractive index and greatly increases the transmittance of the device by introducing inorganic titanium dioxide (TiO2) nanoparticles (NP) to the organic PI. The highly refractive TiO2 NPs were surface-treated with stearic acid comprising long alkyl chains to improve their dispersibility and uniformly dispersed in the PI matrix by simply stirring the mixture. The hybrid PI mixture was spin-coated on the ITO substrate, and the resulting LC cell exhibited excellent electro-optical properties. In addition, the reliability of the LC cells was enhanced by the inclusion of the TiO2 NPs, which was confirmed through the evaluation of voltage holding ratio, residual direct current, and LC cell reliability. Overall, functional hybrid PI can be used in advanced display technology for next-generation LC devices that require high transmittance and reliability.

Preparation and characterization of photo‐decomposable ester‐containing semi‐alicyclic polyimide alignment layers for potential applications in in‐plane switching thin‐film transistor liquid crystal display devices

“…The voltage corresponding to the transmittance at 10% was defined as the threshold voltage ( V th ) of the LC cells, which are shown in Table 2. Although the V‐T plots of one LC minicell might be influenced by various conditions, such as the fabricating procedures for the cells, and the material properties of LC, alignment layer, and so on, some valuable information related with the structural effects of the PI alignment layers might be revealed with the prerequisites of the similar cell‐making conditions and the same LC materials 56 . It could be deduced from Figure 11 that the V th values of the minicells increased with the order of PI‐I a (3.5 V) < PI‐I b (3.6 V) < PI‐II a (4.0 V).…”

“…Although the V-T plots of one LC minicell might be influenced by various conditions, such as the fabricating procedures for the cells, and the material properties of LC, alignment layer, and so on, some valuable information related with the structural effects of the PI alignment layers might be revealed with the prerequisites of the similar cellmaking conditions and the same LC materials. 56 It could be deduced from Figure 11 that the V th values of the minicells increased with the order of PI-I a (3.5 V) < PI-I b (3.6 V) < PI-II a (4.0 V). Generally, the V th value of one minicell is closely related with the interactions between the LC and the PI alignment layers.…”

Recent Advances in Electro-Optic Response of Polymer-Stabilized Cholesteric Liquid Crystals

“…To alleviate the potential issue of image sticking, the choice of negative Δε LC and alignment layer would need to be optimized to reduce the affinity for the ions to adsorb to the alignment layer [ 81 ]. Another potential solution that has been shown to reduce image sticking is through doping of either the LC phase or alignment layer with nanoparticles such as γ-Fe2O3 [ 82 ] and TiO2 [ 83 ]. The doping method would need to be further explored in PSCLC systems, as the proposed mechanism for reducing image sticking relies on ion impurities being absorbed by the nanoparticles, which could reduce tuning ability.…”

56‐5: HTR‐ADS—A Novel Ultra‐High Transmittance Display Mode

“…In recent years, the competition in the panel industry has become increasingly fierce, especially in the fields of low cost, high transmittance [1][2][3] , high contrast 4,5 , and so on. As mentioned the above, the panel transmittance is the top priority of competition point among each panel factory.…”