Inter-Backbone Charge Transfer as Prerequisite for Long-Range Conductivity in Perylene Bisimide Hydrogels

Area of Science:

• Supramolecular chemistry
• Materials science
• Nanotechnology

Background:

• Hydrogelation enables the assembly of molecules into functional soft materials.
• Perylene bisimide (PBI) hydrogels possess tunable properties based on their supramolecular structure.
• Understanding structural motifs is crucial for optimizing PBI hydrogel conductivity.

Purpose of the Study:

• To elucidate the comprehensive structural picture of PBI hydrogels.
• To investigate the role of structural motifs in long-range conductivity.
• To explore the potential of PBI hydrogels in sensing applications.

Main Methods:

• Supramolecular self-assembly of perylene bisimide molecules.
• Structural characterization of hydrogel networks.
• Electrical conductivity measurements under varying conditions.

Main Results:

• Identified nanocrystalline ribbon-like structures as the primary electronic and structural units.
• Demonstrated that charge transfer between these ribbons is mediated by polar solvent bridges.
• Observed a 5-orders-of-magnitude increase in conductivity upon exposure to polar vapor.

Conclusions:

• The long-range conductivity of PBI hydrogels is limited by charge transfer between electronic backbones.
• Nanocrystalline ribbons and polar solvent bridges are critical for charge transport.
• The interplay between structure and medium is vital for designing PBI hydrogel-based devices.