Photoconductivity Switching in Semiconducting Two-Dimensional Crystals via Molecular Tetris

Area of Science:

• Materials Science
• Organic Chemistry
• Solid-State Physics

Background:

• Two-dimensional (2D) organic materials typically rely on covalent bonding and π-π stacking for structural integrity.
• The stability of 2D layers formed by weaker noncovalent interactions has been a significant challenge in materials design.

Purpose of the Study:

• To investigate the feasibility of constructing stable 2D organic materials using solely noncovalent interactions.
• To explore the mechanical properties and functional applications of these novel noncovalently bonded 2D materials.

Main Methods:

• A 'molecular Tetris' strategy was employed to assemble polycyclic aromatic heterocycles.
• A single-crystal-to-dissolution-to-single-crystal transformation method was used to obtain X-ray mountable single crystals.
• Macromechanical analysis via nanoindentation and X-ray diffraction, solid-state spectroscopy, and electrochemical studies were performed.

Main Results:

• A graphite-like 2D layered material stabilized purely by noncovalent connectivity (intermolecular and π-π interactions) was successfully synthesized.
• The material demonstrated shearing behavior under mechanical stress, quantified by nanoindentation.
• Reversible iodine intercalation into the 2D lattice significantly enhanced photoconductivity by 17-fold.

Conclusions:

• Noncovalent interactions are sufficient to stabilize robust 2D organic layered materials.
• The developed material exhibits promising properties for optoelectronic applications due to reversible intercalation and enhanced photoconductivity.