Excitonic Properties of sp3-Doped (6,5) Single-Walled Carbon Nanotubes as a Single Photon Emitter

Single-walled carbon nanotubes (SWCNTs) doped with <i>sp3</i> defects are a promising class of optoelectronic materials with bright tunable photoluminescence and demonstrated single-photon emission (SPE). Experimental and theoretical studies on <i>sp3</i>-defective (6,5) SWCNT performed by us suggest that the introduction of the defect leads to presence of a localized unpaired electron around the <i>sp3</i> defect site and an in-gap dispersionless state. Here, we study the low-energy excitations associated with this defect state in order to better understand the role of <i>sp3</i> defects in SPE. Many-body perturbation theory within the GW/BSE approximation predicts strong excitonic effects with an exciton binding energy of ~ 1 eV for both the pristine and defective (6,5) SWCNT. Additionally, GW/BSE, as well as hybrid time-dependent density functional theory, indicate that the exciton in the enhanced photoluminescence state is a linear combination of the pristine-like transition and that involving the in-gap defect state. Lastly, we present studies of carrier-phonon scattering as a cause of exciton dephasing in <i>sp3</i>-defective (6,5) SWCNT by considering electron-phonon and hole-phonon interactions using the independent boson model.<br/>The authors acknowledge financial support from NSF DMR-19005990.