Nanoscale Effects in One-Dimensional Columnar Supramolecular Ferroelectrics.

Area of Science:

• Materials Science
• Organic Electronics
• Supramolecular Chemistry

Background:

• Organic ferroelectrics offer environmentally friendly and cost-effective alternatives for memory devices.
• Hydrogen-bonded organic ferroelectrics exhibit remanent polarization comparable to inorganic materials.
• Nanoscale fabrication is crucial for achieving high-density memory using organic ferroelectrics.

Purpose of the Study:

• To investigate the ferroelectric properties of a pyrene derivative with tetradecylamide chains.
• To explore the effect of mixing ferroelectric and non-ferroelectric pyrene derivatives on nanoscale aggregation and ferroelectricity.
• To determine the minimum length required for one-dimensional (1D) ferroelectricity in mixed liquid crystals.

Main Methods:

• Synthesis of a pyrene derivative (1) with four tetradecylamide chains and chiral derivatives (S-2, R-2).
• Formation of homogeneous mixed liquid crystals ((1)1-x(S-2)x) by varying the ratio of ferroelectric (1) and non-ferroelectric (S-2) components.
• Characterization of the liquid crystalline phases and ferroelectric properties of the pure and mixed systems.

Main Results:

• Compound 1 formed a 1D column exhibiting ferroelectricity in the discotic hexagonal columnar (Colh) phase.
• Chiral derivatives S-2 and R-2 did not form the Colh phase or exhibit ferroelectricity.
• Ferroelectricity was maintained in mixed liquid crystals (1)1-x(S-2)x for x ≤ 0.03, requiring an average molecular length of ~12 nm.

Conclusions:

• The nanoscale aggregation state of organic ferroelectrics can be controlled by mixing with non-ferroelectric components.
• 1D supramolecular ferroelectricity in organic materials can be achieved at the nanoscale, comparable to inorganic ferroelectrics.
• This study demonstrates a pathway for fabricating nanoscale organic ferroelectric memory devices.