Huang Ziyang, Zhang Zehao, Zhang Rongjie, Ding Baofu, Yang Liu, Wu Keyou, Xu Youan, Zhong Gaokuo, Ren Chuanlai, Liu Jiarong, Hao Yugan, Wu Menghao, Ma Teng, Liu Bilu
Shenzhen Graphene Centre, Shenzhen Key Laboratory of Advanced Layered Materials for Value-added Applications, Tsinghua-Berkeley Shenzhen Institute and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
Institute of Technology for Carbon Neutrality, Faculty of Materials Science and Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
Natl Sci Rev. 2024 Mar 21;11(5):nwae108. doi: 10.1093/nsr/nwae108. eCollection 2024 May.
Electro-optical effect-based liquid crystal devices have been extensively used in optical modulation techniques, in which the Kerr coefficient reflects the sensitivity of the liquid crystals and determines the strength of the device's operational electric field. The Peterlin-Stuart theory and the O'Konski model jointly indicate that a giant Kerr coefficient could be obtained in a material with both a large geometrical anisotropy and an intrinsic polarization, but such a material is not yet reported. Here we reveal a ferroelectric effect in a monolayer two-dimensional mineral vermiculite. A large geometrical anisotropy factor and a large inherent electric dipole together raise the record value of Kerr coefficient by an order of magnitude, till 3.0 × 10 m V. This finding enables an ultra-low operational electric field of 10-10 V m and the fabrication of electro-optical devices with an inch-level electrode separation, which has not previously been practical. Because of its high ultraviolet stability (decay <1% under ultraviolet exposure for 1000 hours), large-scale production, and energy efficiency, prototypical displayable billboards have been fabricated for outdoor interactive scenes. This work provides new insights for both liquid crystal optics and two-dimensional ferroelectrics.
基于电光效应的液晶器件已广泛应用于光调制技术中，其中克尔系数反映了液晶的灵敏度，并决定了器件工作电场的强度。彼得林 - 斯图尔特理论和奥康斯基模型共同表明，在具有大几何各向异性和固有极化的材料中可以获得巨大的克尔系数，但尚未有此类材料的报道。在此，我们揭示了单层二维矿物蛭石中的铁电效应。大几何各向异性因子和大固有电偶极矩共同将克尔系数的记录值提高了一个数量级，达到3.0×10⁻¹⁰ m² V⁻²。这一发现使得能够实现10⁻¹⁰ V m⁻¹的超低工作电场，并制造出电极间距达英寸级的电光器件，而这在以前是不实际的。由于其高紫外线稳定性（在1000小时紫外线照射下衰减<1%）、大规模生产能力和能源效率，已制造出用于户外互动场景的原型可显示广告牌。这项工作为液晶光学和二维铁电体都提供了新的见解。
