onelayer

Onelayer is a term used in materials science to denote a structure consisting of a single layer of atoms or molecules. In practice, it is often synonymous with monolayer or single-layer, particularly in discussions of two-dimensional (2D) materials. A onelayer material is typically only one atomic or molecular layer thick, and its properties can differ markedly from the bulk material.

Onelayer structures are typically prepared through methods such as mechanical exfoliation (peeling a single layer from a bulk crystal), chemical vapor deposition or molecular beam epitaxy to grow a single layer on a substrate, and various solution-based or chemical synthesis approaches. Well-known onelayer examples include graphene, monolayer transition metal dichalcogenides (such as MoS2 and WS2), and monolayer hexagonal boron nitride (h-BN). Graphene onelayers exhibit high in-plane strength and exceptional electrical conductivity but lack a natural bandgap, while MoS2 and similar monolayers can have a direct bandgap around 1.8 eV, enabling optoelectronic applications.

Key properties of onelayer materials include reduced thickness, enhanced surface area, and electronic or optical structures that can differ significantly from bulk counterparts. These features give rise to potential applications in nanoelectronics, optoelectronics, photovoltaics, sensing, catalysis, and energy storage. Characterization often employs Raman spectroscopy, atomic force microscopy, scanning tunneling microscopy, and electron microscopy to assess thickness, defects, and electronic structure.

Challenges for onelayer materials include large-area uniform synthesis, defect control, environmental stability, and interactions with substrates, which can influence performance in devices. See also: monolayer, two-dimensional materials, graphene, transition metal dichalcogenide monolayers.