Effect of medium dielectric constant on the physical properties of single-walled carbon nanotubes

The photophysical properties of semiconducting single walled carbon nanotubes (SWNTs) in different environments are analyzed by steady-state and time-resolved photoluminescence (PL) spectroscopy. The PL emission of SWNTs shows a red shift with the increase of the dielectric constant of the environments. The solvatochromic shift depends on the structural properties of the nanotubes and reaches almost 100 milli-electron volts in the case of (7, 5) tubes. These experimental results allow deriving a relationship between the PL shift and the structure of SWNTs. Moreover, the dynamics of ‘bright’ excitons in semiconducting SWNTs and the effect of the medium on the decay of the excitons are discussed by using time-resolved spectroscopy.