TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The solvent is a polar solvent or an organic solvent.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The polymer is water-soluble or organic soluble. The carbon nanotube is: a single-walled or a double-walled; or a thin-walled or a multi-walled carbon nanotube. The substrate is implemented as a transparent substrate on which a conductive electrode is coated, a conductive substrate or an insulating substrate. The carbon nanotube film further comprises nanocarbon black. In the carbon nanotube electrode, the substrate and the carbon nanotube film are transparent. The carbon nanotube film of the carbon nanotube electrode has a thickness of 0.05-20 mu m. Preferred Method: The carbon nanotubes film is formed by using one of: a spray or spinning method for spraying or spinning the dispersion solution on the substrate by using an electric field; or a method using the dispersion solution comprising a doctor blade method, a screen printing method, a spray method, a spin coating method, a painting method or a dipping method, where the spray or spinning method using an electric field is one of an electro-spray method, an electro-blown method and/or a flash spinning method. The method of preparing a carbon nanotube electrode further comprises thermally compressing the carbon nanotube film. The nanocarbon black is added to the dispersion solution thus to be sprayed or spin coated or an additional dispersion liquid containing nanocarbon black is sprayed or spin-coated. EXAMPLE - 4-Styrenesulfonic acid sodium salt hydrate (40 g) and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) (2.96 g) were dissolved in ethylene glycol (200 ml). A sodium metabisulfite solution (1.37 g) and a potassium persulfate solution (2.59 g) were added to the mixture solution at 60 degrees C and under a nitrogen atmosphere. Then, the resulting solution was stirred for one hour to obtain polystyrenesulfonate sodium salt (PSSNa)-TEMPO. Multi-walled carbon nanotubes (MWNT) (20 mg) were added to PSSNa-TEMPO (2 g). Then, the mixture was stirred at 120 degrees C for 24 hours. Next, PSSNa was grafted to MWNT by a radical graft reaction, to obtain an MWNT-g-PSSNa. The synthesized MWNT-g-PSSNa was filtered and then was re-dispersed to distilled water by using an ultra-sonicator. The MWNT-g-PSSNa (1 wt.%) was dispersed to a mixture solution between water and ethanol (1:1), respectively. Then, the MWNT-g-PSSNa dispersion solution was electro-sprayed on fluorine-doped tin oxide substrate by using the electro-spray device to obtain a modified carbon nanotube films having various thicknesses.