"Red Carbon": A Rediscovered Covalent Crystalline Semiconductor.

Area of Science:

• Materials Science
• Polymer Chemistry
• Semiconductor Physics

Background:

• Carbon suboxide (C3O2) is a molecule known for spontaneous polymerization into conjugated structures.
• Despite its potential, the properties and applications of this carbonaceous material remain underexplored.
• This study aims to reintroduce "red carbon" as a functional polymeric semiconductor.

Purpose of the Study:

• To simplify the synthesis and control the structure of carbon suboxide polymers.
• To elucidate the chemical structure and electronic properties of the resulting material.
• To evaluate the material's potential for photocatalytic applications.

Main Methods:

• Solution polymerization adapted for controlled synthesis at low temperatures (0°C).
• Spectroscopic and elemental analyses to determine chemical structure.
• Density functional theory (DFT) calculations for structural and electronic properties.
• Optical analysis to confirm bandgap properties.

Main Results:

• A crystalline covalent material, identified as conjugated ladder polypyrone ribbons, was synthesized.
• DFT calculations predicted an AB stack crystalline structure and direct bandgap semiconducting nature.
• Optical analysis confirmed a medium bandgap, consistent with DFT predictions.
• The material demonstrated promising photocatalytic activity under blue light irradiation.

Conclusions:

• The developed condensation-aromatization route enables straightforward synthesis of conjugated ladder polymers at low temperatures.
• Carbon suboxide polymers exhibit semiconductor properties with potential for photocatalysis.
• This work highlights the potential of "red carbon" and inspires further research into low-temperature synthesis of carbonaceous materials.