Conductive Glassy Nonconjugated Open-Shell Radical Polymer with Organosulfur Backbone for Macroscopic Conductivity.

Area of Science:

• Materials Science
• Polymer Chemistry
• Organic Electronics

Background:

• Nonconjugated organic radicals possess unique properties due to their radical pendant sites.
• Radical polymers show improved processability, stability, and optical characteristics compared to doped conjugated polymers.
• Existing organic radical polymer conductors, like those based on TEMPO radicals, need further design optimization for enhanced charge transport.

Purpose of the Study:

• To develop amorphous, nonconjugated radical polymers with backbone-pendant group interaction and low glass transition temperature for rapid charge transport.
• To investigate the relationship between polymer structure, charge transport mechanisms, and optical properties in radical polymers.
• To achieve conductivity exceeding 32 S m^-1 while maintaining high optical transparency.

Main Methods:

• Synthesis of amorphous, nonconjugated radical polymers featuring backbone-pendant group interactions.
• Characterization of polymer properties including glass transition temperature, charge transport, and optical transparency.
• Analysis of the correlation between polymer morphology, molecular interactions, and charge mobility.

Main Results:

• Demonstrated rapid charge transport in the solid state, achieving conductivity greater than 32 S m^-1.
• Attributed high conductivity to the formation of local ordered regimes with energetically favored orientations due to strong backbone-pendant group coupling.
• Achieved high optical transparency (up to 98% in a 1.5 μm thick film) owing to the nonconjugated nature of the polymer.

Conclusions:

• The developed radical polymer design enables significantly enhanced charge transport in amorphous systems.
• Strong coupling between backbone and pendant groups effectively modulates polymer packing and facilitates electronic communication.
• These findings present a new paradigm for designing high-performance organic radical polymers for next-generation electronic applications.