Fig. 3. Spectroscopic characterization of postdeposition treatments.

(A) XPS of CNT arrays showing C 1s, N 1s, and Cl 2p peaks following solvent rinsing and vacuum annealing. A.U., arbitrary units. (B) Optical absorbance spectra of CNT array films deposited on quartz with the approximate spectral windows corresponding to the first three CNT S_ii transitions marked for clarity. Black open circles correspond to “as-deposited,” red open triangles correspond to “rinsed,” and blue open squares correspond to “rinsed + annealed” treatments. (C) FTIR spectroscopy of 10-nm-thick PFO-BPy films. Vacuum annealing reduces the alkyl C–H stretching modes centered at 2855 and 2926 cm⁻¹, corresponding to loss of the polymer side chains.