In Situ Investigation of Defect Site Formation in Carbon Nanotubes

Abstract

Semiconducting single-walled carbon nanotubes (SWCNTs) exhibit a photostable excitonic fluorescence in the short wave near-infrared (SWIR). Recently, the covalent functionalization of nanotubes opened new avenues to manipulate their excitonic fluorescence [1]. These “organic color centers (OCCs)” act as localized potential wells on the nanotube surface, trapping locally otherwise diffusing excitons. This effectively results in an increase in the SWCNT emission, the trapped excitons avoiding possible quenching sites along the nanotube surface (structural defects, nanotube ends) [2]. This new radiative pathway results in a shifting of the SWCNT emission towards longer wavelengths and allows SWCNT excitation on their first-order excitonic transition (ca. SWIR) [3]. Altogether, these properties make OCC-functionalized SWCNTs particularly attractive for various applications ranging from biological imaging to quantum information. Yet, the functionalization reaction of SWCNTs with OCC is still poorly understood, stochastic and, as a result, poorly controlled. To gain knowledge and control over these reactions, we developed a two-color imaging platform to image simultaneously both the SWCNT and OCC emissions in situ during the functionalization reaction [4]. We will present how this platform allows to monitor the kinetics of the functionalization reaction and further discuss our findings which provide insights on the interactions existing between OCCs and the SWCNT surface.[1] A. H. Brozena et al., Nat. Rev. Chem., vol. 3, no. 6, pp. 375–392, 2019[2] N. Danné et al., ACS Nano, vol. 12, no. 6, pp. 6059–6065, 2018[3] A. K. Mandal et al., Sci. Rep., vol. 10, no. 1, pp. 1–9, 2020[4] B.P. Lambert et al., in preparation