Molecular screening effects on exciton-carrier interactions in suspended carbon nanotubes

• Published in: Applied physics letters Vol. 113; no. 12
• Main Authors: Uda, T., Tanaka, S., Kato, Y. K.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 17-09-2018
• Subjects: Applied physics; Carbon nanotubes; Chemical potential; Contact potentials; Dependence; Electric potential; Excitons; Nanotubes; Organic chemistry; Photoluminescence; Screening; Spectrum analysis
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.5046433

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.