US Ireland R&D Partnership: Ferroelectric and Electroclinic Effects in Nano-particle Doped de Vries Smectic Liquid Crystals: Molecular Organisation and Order

美国 爱尔兰 R

• 批准号: 1410649
• 负责人: Satyendra Kumar
• 金额: $ 38.5万
• 依托单位: Kent State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1410649&HistoricalAwards=false
• 关键词: US; Ireland; R&D; Partnership; Ferroelectric

Non-Technical Abstract:The liquid crystal technology currently used in flat panel displays has reached the limits of switching speed and contrast ratio, and cannot meet the requirements of next generation of high-performance displays. Two relatively new and less studied liquid crystal switching phenomena, known as the electroclinic and ferroelectric effects, hold the promise of more than a thousand times faster switching speeds and much higher contrast than the present liquid crystal displays. With support from the Solid State and Materials Chemistry Program in the Division of Materials Research, this interdisciplinary research team under the US Ireland R&D Partnership program of the National Science Foundation seeks to design and synthesize new liquid crystal molecules that optimize these switching phenomena, study the molecular organization and response of these materials to applied electric fields, investigate the role of dissolved nano-particles of different shapes and sizes in improving their performance, and develop protocols and processes leading to the fabrication of proof-of-concept display cells based on these two transformative technologies. The project brings together graduate students, and junior and senior researchers from the US, Ireland, and Northern Ireland and provides them with opportunities to collaborate and acquire diverse sets of technical skills not available in any one laboratory. The project educates students in cutting edge experimental and analytical techniques such as micro-Raman scattering, specialized optical methods, and high-resolution synchrotron x-ray studies at the Advanced Photon Source (Argonne National Laboratory) and the National Synchrotron Light Source (Brookhaven National Laboratory). Participation in research activities during summer by undergraduate students at Kent State University and from (two-year) Stark State College, science demonstrations at local schools, and laboratory visits by K-12 students are among the key educational components of the project. Technical Abstract:de Vries smectic liquid crystals exhibit negligible thermal expansion and hence offer an important and perhaps the only pathway to technological applications of their ferroelectric and electroclinic properties. This US Ireland R&D Partnership project strives to understand the phenomena underlying the remarkable thermal characteristics, the electroclinic and ferroelectric effects, their dependence on molecular structure, and to develop the essential surface alignment protocols required for device applications. The research team plans to synthesize and study molecules with different ratios of siloxane to hydrocarbon segments, chiral centers, and per fluorinated molecules with a hydrocarbon end-segment to acquire the ability to predict their behavior from molecular structure. This is achieved using state-of-the-art experimental techniques such as synchrotron X-ray diffraction, Raman and IR scattering, and wideband dielectric spectroscopy. Determination of the orientational order parameters, orientational distribution function, director tilt order parameter, and smectic order parameter are critical in resolving which of the theoretical models, diffuse cone or sugarloaf, is valid. Doping of liquid crystals with nano-particles, -rods, and -discs is planned to improve the response time, threshold voltage, and contrast ratio. The project team plans to acquire a comprehensive understanding of these systems and demonstrate proof-of-concept new generation electroclinic and ferroelectric liquid crystal devices for displays, optical communications, and sensor applications.

非技术摘要：目前用于平板显示器的液晶技术已经达到了开关速度和对比度的极限，无法满足下一代高性能显示器的要求。两种相对较新且研究较少的液晶切换现象，称为电诊所和铁电效应，有望比目前的液晶显示器快一千倍以上的切换速度和更高的对比度。在材料研究部固态与材料化学项目的支持下，美国国家科学基金会美国爱尔兰研发合作伙伴项目下的这个跨学科研究团队&寻求设计和合成新的液晶分子，优化这些开关现象，研究这些材料的分子组织和对外加电场的响应，研究不同形状和尺寸的溶解纳米颗粒在提高其性能方面的作用，并开发基于这两种变革性技术的概念验证显示单元制造的协议和工艺。该项目汇集了来自美国，爱尔兰和北方爱尔兰的研究生，初级和高级研究人员，并为他们提供合作机会，并获得任何一个实验室都无法获得的各种技术技能。该项目在先进光子源（阿贡国家实验室）和国家同步加速器光源（布鲁克海文国家实验室）对学生进行尖端实验和分析技术的教育，如显微拉曼散射、专业光学方法和高分辨率同步加速器X射线研究。该项目的主要教育内容包括：肯特州立大学和斯塔克州立学院（两年制）的本科生在夏季参加研究活动，在当地学校进行科学演示，K-12学生参观实验室。技术摘要：德弗里斯近晶液晶显示出可忽略的热膨胀，因此提供了一个重要的，也许是唯一的途径，其铁电和电诊所性质的技术应用。这个美国爱尔兰研发合作项目致力于了解显着的热特性，电诊所和铁电效应，其依赖于分子结构的现象，并制定必要的表面排列协议所需的设备应用。研究小组计划合成和研究具有不同比例的硅氧烷与烃链段、手性中心的分子，以及具有烃端基的全氟化分子，以获得从分子结构预测其行为的能力。这是实现使用国家的最先进的实验技术，如同步加速器X射线衍射，拉曼和红外散射，和宽带介电光谱。取向序参数，取向分布函数，导演倾斜序参数，和近晶序参数的确定是解决的理论模型，扩散锥或糖面包，是有效的关键。掺杂的液晶与纳米粒子，棒，和盘计划，以提高响应时间，阈值电压，和对比度。项目团队计划全面了解这些系统，并展示用于显示器、光通信和传感器应用的新一代电诊所和铁电液晶器件的概念验证。