  Near-infrared electroluminescence from carbon-based emitters, especially in
the second biological window (NIR-II) or at telecommunication wavelengths, is
difficult to achieve. Single-walled carbon nanotubes (SWCNTs) have been
proposed as a possible solution due to their tunable and narrowband emission in
the near-infrared and high charge carrier mobilities. Furthermore, the covalent
functionalization of SWCNTs with a controlled number of luminescent sp$^{3}$
defects leads to even more red-shifted photoluminescence with enhanced quantum
yields. Here, we demonstrate that by tailoring the binding configuration of the
introduced sp$^{3}$ defects and hence tuning their optical trap depth we can
generate emission from polymer-sorted (6,5) and (7,5) nanotubes that is mainly
occurring in the telecommunication O-band (1260-1360 nm). Networks of these
functionalized nanotubes are integrated in ambipolar, light-emitting
field-effect transistors to yield the corresponding narrowband near-infrared
electroluminescence. Further investigation of the current and carrier
density-dependent electro- and photoluminescence spectra enable insights into
the impact of different sp$^{3}$ defects on charge transport in networks of
functionalized SWCNTs.
