  Their outstanding electrical and optical properties make semiconducting
single-walled carbon nanotubes (SWCNTs) highly suitable for charge transport
and emissive layers in near-infrared optoelectronic devices. However, the
luminescence spectra of SWCNT thin films on commonly used glass and Si/SiO2
substrates are often compromised by broadening of the main excitonic emission
and unwanted low-energy sidebands. Surface passivation with a commercially
available, low dielectric constant, cross-linked bis-benzocyclobutene-based
polymer (BCB) enhances the emission properties of SWCNTs to the same level as
hexagonal boron nitride (h-BN) flakes do. The presence of BCB suppresses
sideband emission, especially from the Y1 band, which is attributed to defects
introduced by the interaction of the nanotube lattice with oxygen-containing
terminal groups of the substrate surface. The facile and reproducible
deposition of homogeneous BCB films over large areas combined with their
resistance against common solvents and chemicals employed during
photolithography make them compatible with standard semiconductor device
fabrication. Utilizing this approach, light-emitting (6,5) SWCNT network
field-effect transistors are fabricated on BCB-treated glass substrates with
excellent electrical characteristics and near-intrinsic electroluminescence.
Hence, passivation with BCB is proposed as a standard treatment for substrates
used for spectroscopic investigations of and optoelectronic devices with SWCNTs
and other low-dimensional emitters.
