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

Electrochemical doping of single-wall carbon nanotube (SWNT) films and conc omitant changes in their electronic states were investigated by in situ mea surements 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 potenti al demonstrated the practicability of fine and continuous tuning of their e lectronic 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 SWNT s. (C) 2001 American Institute of Physics.