Scientific exploration of ferroelectric liquid matter: elusidation of physical/chemical features and its functional application

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K15438
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 29010:Applied physical properties-related
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: Nishikawa Hiroya 国立研究開発法人理化学研究所, 創発物性科学研究センター, 特別研究員 (50835519)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 強誘電性ネマチック / フェロネマチック / 巨大分極 / トポロジー / フォトコンデンサ / キャパシタ / 極性らせん構造

Outline of Final Research Achievements

By focusing on unique features, i.e. fluidity, topology and polarization, of ferroelectric nematic material (NF), I successfully create a polar helix and a novel device using the gigantic polarization of NF. I demonstrate that in the polar helix, the local nematic director is non-degenerated, that is, the head-and-tail symmetry is broken, and electrically/quickly inter-convertibility of selective reflection related to the half-/full-pitch bands in the distorted helix. On the other hand, I develop a novel device a.k.a. a photo-condenser by just blending NF and a photo-trigger with visible light responsivity. I demonstrate that in the photo-condenser, the reversible trans-cis isomerization of the photo-trigger under blue (415 nm) and green (525 nm) light irradiation causes a switch between two liquid-crystalline phases that exhibit drastic tuning of dielectric permittivities (200 < ε < 18,000), with a rapid response time (< 30 s) and excellent reversibility (~ 100 cycles).

Free Research Field

液晶化学、強誘電材料、有機合成化学

Academic Significance and Societal Importance of the Research Achievements

巨大分極特性（誘電率、自発分極）に加え高い流動性をもつユニークな性質を伴う強誘電性ネマチック（NF）材料は国内外で多くの関心を集めている。本研究では、NF材料において、流動性・トポロジー・分極の相互関係と強誘電発現起源の相関理解に取り組み、極性トポロジーが織り成す新規構造（極性らせん構造）の創製・機能評価や、巨大分極特性を利用した革新的機能性マテリアル（フォトコンデンサ）の創製に成功した。本成果により、NF材料は既存材料の常識を覆すポテンシャルをもつことを実証した。強誘電発現起源のさらなる深化により、NF材料の自在設計が可能となり、学術分野ならびに産業分野全体に波及効果をもたらすと確信する。