Two dimensional materials are crystalline solids composed of a single or just a few atomic layers. Their extreme thinness gives them electronic, optical and mechanical properties that differ radically from their bulk counterparts and can be engineered with great precision.

Graphene, a single layer of carbon atoms in a hexagonal lattice, is the archetype. It combines exceptional electrical conductivity, high carrier mobility, mechanical strength and flexibility, and remarkable thermal conductivity. These features make it a candidate for high speed transistors, transparent electrodes, flexible electronics and advanced composites.

Beyond graphene, transition metal dichalcogenides such as MoS2, WS2 and others form a broad family of semiconducting 2D materials. Many of them have direct band gaps in the visible range, enabling efficient light absorption and emission. Their electronic band structures can be tuned by strain, thickness, stacking and external fields, which is valuable for transistors, photodetectors and light emitting devices. Strong Coulomb interactions in these atomically thin layers lead to tightly bound excitons and rich many body physics.

Other important classes include hexagonal boron nitride, an insulating 2D material with an atomically flat surface used as a dielectric and encapsulation layer, and 2D oxides and nitrides with diverse functionalities.

Stacking different 2D layers into van der Waals heterostructures allows nearly arbitrary combinations of metals, semiconductors and insulators without lattice matching constraints. This opens a route to designer materials with tailored properties for nanoelectronics, spintronics, valleytronics and quantum technologies. Research also explores scalable synthesis methods, stability, defect control and integration with existing semiconductor processes to move these materials from fundamental studies to real world applications.