γ-Graphyne Two-dimensional Polymerization and Functionalization for Film Formation and Controlled Exfoliation

Background

The continued miniaturization of electronic and photonic devices has driven intense research into two-dimensional carbon materials that combine high charge mobility, mechanical robustness and thermal management. Traditional graphene offers high conductivity and strength but suffers from zero band gap and lacks directional electronic properties, limiting its application in semiconducting architectures. As a result, sp¹–sp² hybrid frameworks like γ-graphyne are targeted for their predicted moderate band gap, intrinsic directional conductivity and self-doping characteristics, attributes that could enable faster transistors, high-efficiency solar cells and advanced energy storage without extensive chemical modification. Current synthetic methodologies for extended γ-graphyne lattices, however, face significant obstacles. Homogeneous cross-coupling routes often rely on unstable or explosive monomers, produce materials with inconsistent sheet size and thickness, and lead to catalyst contamination. High-temperature vapor deposition and pyrolysis are incompatible with acetylenic linkages, yielding amorphous carbon or graphene-like structures rather than true sp¹–sp² networks. Moreover, multistep organic syntheses yield only short, poorly soluble oligomers, and edge functionalities introduced during synthesis can hinder exfoliation into few-layer sheets and complicate subsequent device integration.

Technology Overview

Liquid-interfacial Sonogashira polymerization produces continuous γ-graphyne films by confining 1,3,5-tribromo-2,4,6-triethynylbenzene monomers at an organic/aqueous interface, yielding polycrystalline, multilayer sheets up to ~100 µm across and under 2 µm thick. Transmission electron microscopy and selected‐area electron diffraction reveal a hexagonal lattice, and X-ray photoelectron spectroscopy confirms a 1:1 ratio of sp–sp² carbon. Residual terminal alkynes and aryl bromides enable post-growth Sonogashira or copper-catalyzed azide–alkyne cycloaddition at sheet edges, boosting solubility and facilitating exfoliation into few-layer flakes. This approach is distinguished by its interfacial confinement and crystallization-assisted mechanism, which deliver better control over sheet size, thickness and defect correction compared to homogeneous methods using unstable precursors. By localizing the reaction at a liquid/liquid boundary it prevents palladium nanoparticle contamination, ensures uniform polymer growth and supports large‐area lattices. Edge-functionalization capabilities further set it apart, allowing tailored solubility and scalable production of high-quality, few-layer γ-graphyne films for advanced electronic, photonic and energy applications.

Benefits

• Scalable synthesis of high-quality, continuous γ-graphyne films with controlled thickness and lateral size
• Direct formation of crystalline, multilayer sheets (up to ∼100 µm) with hexagonal lattice symmetry
• Residual terminal alkynes and aryl halides enable post-synthesis edge functionalization for improved solubility and processability
• Liquid-interfacial method provides better reaction control and avoids palladium nanoparticle contamination
• Edge-modified γ-graphyne exfoliates into monolayer/few-layer flakes, facilitating thin-film applications
• Inherent moderate band gap, ultrafast charge mobility, and directional conductivity yield doping-free semiconducting behavior
• Promising multifunctionality across electronics, photonics, energy storage, catalysis, and separation technologies

Applications

• High-speed transistor channels
• Optoelectronic device substrates
• Lithium-ion battery electrodes
• Supercapacitor electrode materials
• Gas separation membrane filters