Indium Tin Oxide-Free Polymer Solar Cells: Toward Commercial Reality - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 203

Fig. 14 a Plot of measured film conductivity as a function of the inverse of mean junction
resistance; b Ultrasonically spray deposited large-area (6 9 6 inch 2 ) SWCNTs film;.
c Comparison of transmission spectra for ITO and SWCNT (with and without PEDOT:PSS).
Inset shows TEM image of ultrasonically sprayed; and d Light (solid lines) and dark (dashed
lines) JV curves for devices on SWNT and ITO transparent electrodes, with and without PEDOT
as an HTL. Inset shows NREL-certified light IV curve for a BHJ device on a SWNT electrode
without an HTL. Reprinted permissions a 2013 American Chemical Society. Reprinted, with
permissions from Ref. [ 45 ]; c 2013 John Wiley and Sons. Reprinted, with permission from Ref.
[ 47 ]; and b, d 2013 American Institute of Physics. Reprinted, with permission from Ref. [ 46 ]
with the use of ultrasonication of the nanotubes dissolved in a solvent. The sur-
factant and/or acid treatments are generally used in addition to ultrasonication to
achieve stable dispersions. However, when these suspensions are deposited as
films, the surfactants are hard to eliminate and require high-temperature thermal
treatment, which is not compatible to flexible substrate such as PET. Such chal-
lenges are constantly being addressed with the rapid progress in processing of
carbon nanotube films. For example, in one method, SWCNTs are dispersed in
aqueous solvents with high molecular weight (*90,000 MW) cellulous-sodium