Article
Chemistry, Multidisciplinary
Kyung Min Lee, Urice Tohgha, Timothy J. Bunning, Michael E. McConney, Nicholas P. Godman
Summary: Controlling the phase behavior of blue phase liquid crystals (BPLCs) can be achieved by varying the concentration of the amorphous crosslinker PETA. PETA stabilizes the BP-I phase and prevents the formation of the BP-II phase. The addition of PETA widens the temperature window of BP-I and polymer stabilization further enhances the properties of BPLCs.
Review
Chemistry, Physical
Kyung Min Lee, Zachary M. Marsh, Ecklin P. Crenshaw, Urice N. Tohgha, Cedric P. Ambulo, Steven M. Wolf, Kyle J. Carothers, Hannah N. Limburg, Michael E. McConney, Nicholas P. Godman
Summary: Cholesteric liquid crystals (CLC) are molecules that self-assemble into helicoidal superstructures with circularly polarized reflection. The resulting optical properties make CLCs a promising technology for various industrial applications. Polymer-stabilized CLCs (PSCLCs), formed via photopolymerization, exhibit a dynamic optical response induced by external stimuli. This review discusses the electro-optic response and potential mechanism of PSCLCs, highlighting multiple identified responses and their potential applications.
Article
Crystallography
Kyung M. Lee, Timothy J. Bunning, Timothy J. White, Michael E. McConney, Nicholas P. Godman
Summary: The study demonstrates that the position and bandwidth of the selective reflection notch in polymer-stabilized cholesteric liquid crystals (PSCLCs) can be adjusted by applying a DC field. The concentration of ions trapped within the polymer network significantly influences the electro-optic response of PSCLC, with photoinitiators increasing ion density in PSCLC. By isolating the contribution of ionic impurities associated with liquid crystal monomers (LCMs) through initiator-less polymerization, the study shows that the tuning or bandwidth broadening of the CLC reflection band depends on the concentration of LCMs and the chirality of the LCM.
Article
Chemistry, Physical
Brian P. Radka, Kyung Min Lee, Nicholas P. Godman, Timothy J. White
Summary: Prior research has shown that polymer networks can stabilize the CLC phase and achieve tunable and switchable electro-optic reconfiguration. Recent studies have demonstrated that structural chirality can be retained in polymer networks stabilized by liquid crystalline monomers. In this study, we show that structural chirality can also be retained in aliphatic, non-liquid crystalline monomers, and PSCLCs prepared from these monomers exhibit reversible electro-optic responses. The role of surface affinity and crosslink density in transferring structural chirality to the liquid crystal media is also explored.
Article
Optics
Risti Suryantari, Yi-hong Shih, Yu-han Shih, Hui-yu Chen, Cen-shawn Wu, Chia-yi Huang
Summary: This work utilizes surface acoustic waves (SAWs) generated by a piezoelectric substrate with an interdigital transducer (IDT) to fabricate a polymer-stabilized blue phase liquid crystal (PS-BPLC) layer. The PS-BPLC layer exhibits a more uniform optical microscope (OM) image and smaller full width at half maximum (FWHM) when a voltage of 2 mV is applied compared to zero voltage. The monodomain structure of the PS-BPLC layer is attributed to the longitudinal and transverse vibrations induced by SAWs in the vertical plane. The proposed method shows potential for low power consumption in the fabrication of reflective optical devices.
Review
Polymer Science
Yong Ye, Li Guo, Tingjun Zhong
Summary: Polymer-stabilized liquid crystals (PSLCs) are versatile materials with polymer networks providing anchoring energy for liquid crystals. This review details various improvements in PSLCs, including polymer-stabilized nematic, cholesteric, blue phase, smectic, ferroelectric, and antiferroelectric liquid crystals. PSLCs offer multiple functionalities, such as reorientation in smart windows and manual tuning of reflection bandwidth in broadband reflectors. PSBPLCs open up new possibilities for displays, modulators, sensors, lasers, lenses, and photonics applications. Polymer networks in PSFLCs or PSAFLCs enhance grayscale memories for flexible displays and energy-saving smart cards. The remaining challenges and research opportunities in PSLCs are also discussed.
Article
Nanoscience & Nanotechnology
Ying Chen, Huaruo Cui, Ran Duan, Ruiqi Tang, Yingping Tong, Dongyu Zhao, Wanli He
Summary: Blue phase liquid crystals (BPLCs) have significant potential as next-generation candidates for liquid crystal displays (LCDs), but they suffer from low brightness and energy efficiency due to the need for an extra backlight device. Carbon dots (CDs), a novel fluorescent carbon nanomaterial, were synthesized and introduced into BPLCs to create photoluminescent blue phase liquid crystals (CDs-BPLCs) with self-photoluminescence. CDs not only improve the stability of BPLCs, but also enhance their optical properties. This research opens up possibilities for the development of novel energy-saving display devices.
Article
Optics
M. M. Jahanbakhshian, M. A. Kiani, M. Arshadi Pirlar, R. Karimzadeh
Summary: The electro-optic effect is an important mechanism for refractive index tuning, and this research measured the quadratic electro-optic coefficient for a graphene oxide film. The results showed a significantly higher coefficient compared to other materials, indicating the potential for improving devices based on this effect. The graphene oxide film's giant electro-optic Kerr coefficient can reduce power consumption and device complexity by requiring a lower electric field.
Article
Chemistry, Multidisciplinary
Steven M. Wolf, Zachary M. Marsh, Steven M. Quarin, Kyung Min Lee, Sushma Karra, Michael E. McConney, Tod A. Grusenmeyer, Nicholas P. Godman
Summary: Nature efficiently produces chiral compounds, making them potential chiral dopants for cholesteric liquid crystal systems. In this study, 10 naturally occurring biomolecules were tested as chiral dopants for CLCs, with progesterone and lithocholic acid derivatives showing promise. Progesterone was highly miscible with nematic liquid crystals and used in responsive liquid crystal devices, while the derivatives of lithocholic acid exhibited blue tuning behavior in polymer stabilized CLCs.
APPLIED SCIENCES-BASEL
(2023)
Article
Chemistry, Physical
Asha Kumari, Sameer Dhawan, Hanuman Singh, V Haridas, Aloka Sinha
Summary: In this study, the stabilization of a nematic liquid crystal using chiral amino acid-based polymers is reported. The effect of molecular weight of structurally similar polymers on the physical parameters of polymer-stabilized liquid crystals (PSLCs) is investigated for the first time. By varying the molecular weight of the polymers, the size of the self-assembled network in the liquid crystal can be adjusted, thereby altering the dielectric, electrical, electro-optic, and optical properties. This method presents several possibilities for fabricating optoelectronic devices.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Chemistry, Multidisciplinary
Yujie Chen, Chenglin Zheng, Wenjie Yang, Jing Li, Feng Jin, Xiuhong Li, Jingxia Wang, Lei Jiang
Summary: This study successfully achieved a broad-temperature reconstructed laser based on a dye-doped polymer-stabilized blue-phase liquid crystal with a high working temperature range. The temperature-tunable behavior of the laser is associated with the phase transition of the unpolymerized content in the system.
ADVANCED MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Sumit Yadav, Poonma Malik, Praveen Malik
Summary: A hybrid blue phase liquid crystal material with a wide blue phase temperature range of over 40K was prepared and its optical, electro-optical, and dielectric properties were investigated. The hybrid material, which contained cadmium telluride quantum dots in polymer stabilized blue phase liquid crystals, showed significantly improved thermal stability compared to other blue phase liquid crystal systems. In addition, the present work also observed a substantial reduction in operating voltage, improvement in transmittance, and increased Kerr constant with a threefold increase in dielectric permittivity in quantum dots doped polymer stabilized blue phase liquid crystals. The examined hybrid materials with wide blue phase temperature range and superior electro-optical properties are expected to be important for various photonic applications.
Article
Chemistry, Physical
Garima Chauhan, Praveen Malik, Akash Deep
Summary: TiO2 nanoparticles dispersed polymer stabilized cholesteric liquid crystal (PSCLC) composites were prepared and studied. The effects of TiO2 NPs doping on the properties of the samples including phases, molecular states, dielectric, electro-optic, and photoluminescence properties were investigated. The morphological studies showed that TiO2 NPs could switch the orientation of liquid crystal molecules into a vertical state at a lower voltage. The permittivity decreased and the dielectric anisotropy and the threshold and saturation voltage improved with the doping of 0.5 wt% TiO2 NPs. The photoluminescence intensity increased with TiO2 NPs concentration but the emission wavelength remained unchanged. This work provides a facile approach to fabricate low energy consumption based electro-optical devices with affordable and eco-friendly nature of TiO2 NPs.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Chemistry, Physical
Vandna Sharma, Pankaj Kumar
Summary: The electro-optically oriented polymer dispersed liquid crystals (PDLCs) are important for their optical transmission, scattering, and optical phase modulation characteristics. In this study, nanoparticles (NPs) were dispersed in normal mode PDLCs using the polymerization induced phase separation method. The results showed that the phase transition temperature from nematic to isotropic decreased and droplet size increased in NPs dispersed PDLCs compared to pristine PDLCs. The reorientation of liquid crystals required a much lower voltage in NPs dispersed PDLCs, and the Kerr phase increased with the dispersion of NPs.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Chemistry, Multidisciplinary
Jamal Hemine, Abdelhamid El Kaaouachi, Mimoun Ismaili, Redouane Douali, Christian Legrand, Abdelylah Daoudi
Summary: In this study, the effect of a polymer network on the ferroelectric phase in a polymer stabilised ferroelectric liquid crystal system was investigated. Electro-optic and dielectric investigations were performed on films with different polymer concentrations, revealing a gradual decrease in dielectric strength with an increase in network density. The Goldstone relaxation mechanism was particularly studied, showing that the relaxation frequency of this mechanism is insensitive to polymer network density.
Article
Optics
Jing Yan, Yufei Xing, Zhengbo Guo, Qing Li
Article
Optics
Jing Yan, Yufei Xing, Qing Li
Article
Physics, Applied
Jing Yan, Qing Li, Kai Hu
JOURNAL OF APPLIED PHYSICS
(2013)
Article
Chemistry, Multidisciplinary
Yifan Liu, Su Xu, Daming Xu, Jing Yan, Yating Gao, Shin-Tson Wu
Article
Physics, Applied
Jing Yan, Jibin Lin, Qing Li, Ruo-Zhou Li
JOURNAL OF APPLIED PHYSICS
(2019)
Article
Chemistry, Multidisciplinary
Daye Ding, Ruozhou Li, Jing Yan, Jiang Liu, Yuming Fang, Ying Yu
Summary: In this study, the influence of microcracks on the RF characteristics of flexible microstrip was investigated by stretching the microstrip and proposing an equivalent circuit model to reveal the mechanisms. The morphology of the microcracks was characterized by SEM and the DC resistance was monitored. The changes in equivalent circuit element parameters (R, L, C) were found to be due to the change in conductive pathways, affecting the transmission and reflection of RF signals.
APPLIED SCIENCES-BASEL
(2021)
Article
Chemistry, Multidisciplinary
Ruo-Zhou Li, Zheyuan Wu, Junhui Ji, Xiaoxing Yin, Jing Yan, Yuming Fang, Ying Yu
Summary: Laser-direct writing has been used to fabricate a wideband open-end termination for microwave devices, utilizing a resistive film overlapped on a strip conductor to reduce fabrication difficulties. The tapered shape of the resistive film enables small gradual changes in impedance, resulting in minimized reflections. The prototype demonstrates good performance with a measured |S-11| over -15 dB from 6 GHz to at least 30 GHz.
APPLIED SCIENCES-BASEL
(2021)
Article
Computer Science, Information Systems
Xingye Fan, Ruozhou Li, Jing Yan, Yuming Fang, Ying Yu
Summary: This study demonstrates a tunable stepped-impedance resonator using liquid crystal, with two resonant frequencies that can be continuously tuned by external voltages. The device achieves wide tunable ranges at a low driving voltage, showing good agreement with simulation results. It also has low insertion loss and high return losses, providing a new protocol for tunable frequency in communication systems.
FRONTIERS OF INFORMATION TECHNOLOGY & ELECTRONIC ENGINEERING
(2021)
Article
Optics
Jing Yan, Zhengbo Guo, Yufei Xing, Qing Li
Proceedings Paper
Crystallography
Daming Xu, Jiamin Yuan, Martin Schadt, Jing Yan, Shin-Tson Wu
EMERGING LIQUID CRYSTAL TECHNOLOGIES X
(2015)
