Electrochemical tuning of electronic states in single-wall carbon nanotubes studied by <i>in situ</i> absorption spectroscopy and ac resistance

Abstract

Electrochemical doping of single-wall carbon nanotube (SWNT) films and concomitant changes in their electronic states were investigated by in situ measurements of optical absorption spectra as well as of ac resistance using a nonaqueous electrolyte solution. A systematic, consistent, and reversible variation of these properties induced by the shift in the electrode potential demonstrated the practicability of fine and continuous tuning of their electronic states. Analysis of the potential dependence of the absorbance at 0.68 eV enabled the estimation of average values of the electron affinity (4.8 eV) and the first ionization potential (5.4 eV) of semiconducting SWNTs.