Abstract
Photoluminescence spectroscopy measurements are performed on suspended carbon nanotubes in a field-effect configuration, and the gate voltage dependence of photoluminescence spectra are compared for the pristine and the molecularly adsorbed states of the nanotubes. We quantify the molecular screening effect on the trion binding energies by determining the energy separation between the bright exciton and the trion emission energies for the two states. The voltage dependence shows narrower voltage regions of constant photoluminescence intensity for the adsorbed states, consistent with a reduction in the electronic bandgap due to screening effects. The charge neutrality points are found to shift after molecular adsorption, which suggests changes in the nanotube chemical potential or the contact metal work function.
Highlights
Photoluminescence spectroscopy measurements are performed on suspended carbon nanotubes in a field-effect configuration, and the gate voltage dependence of photoluminescence spectra are compared for the pristine and the molecularly adsorbed states of the nanotubes
The Coulomb interactions are enhanced in carbon nanotubes (CNTs) because of the limited screening in onedimensional systems,[1,2] which result in stable exciton and trion formation even at room temperature.[3,4,5,6]
Comparing the gate voltage dependent PL from nanotubes before and after molecular adsorption, we find differences in the emission energies as a)Author to whom correspondence should be addressed: yuichiro.kato@riken.jp well as the voltage dependence
Summary
Photoluminescence spectroscopy measurements are performed on suspended carbon nanotubes in a field-effect configuration, and the gate voltage dependence of photoluminescence spectra are compared for the pristine and the molecularly adsorbed states of the nanotubes. The voltage dependence shows narrower voltage regions of constant photoluminescence intensity for the adsorbed states, consistent with a reduction in the electronic bandgap due to screening effects.
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