Dendritic morphology in homeotropically aligned discotic films.

Area of Science:

• Materials Science
• Organic Electronics
• Supramolecular Chemistry

Background:

• Discotic liquid crystals (DLCs) exhibit self-orientation properties crucial for electronic applications.
• Hexa-alkylether-substituted hexa-peri-hexabenzocoronene (HHCB) is a DLC that self-orients upon cooling.
• Dendritic morphologies with optical variations are observed during HHCB solidification.

Purpose of the Study:

• To investigate the structural basis of optical differences in HHCB dendritic structures.
• To understand the self-organization and solidification process of HHCB.
• To assess the implications of observed morphologies on charge transport in organic electronic devices.

Main Methods:

• Microfocus synchrotron radiation experiments for local structural analysis.
• Three-dimensional confocal surface measurements for morphological analysis.
• Optical microscopy to observe dendritic formation and optical variations.

Main Results:

• Identical supramolecular order was confirmed in both dendritic and peripheral areas of HHCB.
• Dendritic structures arise from a dewetting process during solidification.
• The dewetting process significantly reduces the contact area between the DLC and the substrate.

Conclusions:

• The observed dendritic morphology in HHCB is a result of dewetting, not a change in molecular order.
• Reduced contact area due to dewetting can negatively impact charge transport efficiency in organic electronic devices.
• Findings are critical for designing future organic electronics utilizing DLCs, optimizing electrode-material interfaces.