(Invited) Controlling Defect-State Emission in Covalently Functionalized Single-Walled Carbon Nanotubes: A Theoretical Perspective

Abstract

Unique electronic and optical properties of chemically semiconducting carbon nanotubes have inspired a wide range of optoelectronic, sensing, imaging and quantum communication applications. As such, a great deal of recent research focuses on strategies toward rigid control of their photoluminescence characteristics. Such strategies include controlling the functionalization species, localized defect geometry, and defect concentration. Our quantum-chemical modeling have shown how chemical surface adducts locally alter the pi-conjugated network of the nanotube surface that leads to a spatial confinement of the electronically excited wavefunctions. Experimental photoluminescence studies reveal a complex structure of electronic states and their dynamics induced by surface modifications. Our simulations suggest an association of these spectroscopic features with deep trap states tied to different specific chemical species, nanotube chiralities and their mod index. Engineering of interfacial surface structures of single-chirality nanotube materials with dopant-induced defects then allowed us for accurate control over energy transfer and luminescence properties. Overall, these results suggest that covalent doping chemistry is a powerful route toward harnessing dynamics of excitons and charges in carbon nanotubes leading to new enhanced optical behaviors.