Controlled Color Centers in SP2 Carbon: Defect Characterization Using Resonant Raman Spectroscopy

Fully controllable materials for single photon emission (SPE) are sought, especially in the telecom region. Single-wall carbon nanotubes (SWCNTs) have exact and unique crystal structures. Every SWCNT of the same (n,m), a vector which describes the angle of the graphene lattice and defines the cylinder diameter, has identical optoelectronic properties, e.g., optical bandgap, in the absence of extrinsic effects. A key development is the addition of single-point covalent modifications to the sp2 lattice to introduce atomic-scale color center defects. These defects localize emission, vastly increase quantum yield, and enable fine spectral tuning through a wide range of chemical modifications. Using highly purified, single-chirality sample sets wrapped with DNA, we have developed a modified chemistry to produce distinctly defective lattice structures. Resonance Raman spectroscopy identified unique features beyond the common “D peak” to characterize the defect types.