Photoluminescence recovery from single-walled carbon nanotubes on substrates

We have observed bright photoluminescence (PL) from single-walled carbon nanotubes (SWNTs) on self-assembly monolayer (SAM) functionized SiO2/Si substrates. By contrast, no PL was observed from pristine SWNTs grown on substrates (SiO2/Si and Al2O3). This suggests a successful blocking of substrate-induced nonradiative decay of excitons. PL recovery from transferred SWNTs on substrates is attributed to breaking chemical bonding between SWNTs and underlying substrates and blocking electron transfer from SWNTs to defect states in SiO2. By analyzing dependence of PL intensity on thickness of SAMs, key constant P for electron transfer in SWNT/SAM/SiO2 system was obtained (beta = 0.11, 0.14 angstrom-1 for the emission region in 1380-1480 and 1480-1580 nm, respectively).