The physical/chemical properties and electrode performance variations of SWNT films in consequence of solution based surfactant elimination processes

The effects of the surfactant elimination from single wall carbon tube (SWNT) films on the physical/electrical properties of SWNT films are concretely studied. The surfactant, which helps to disperse the SWNTs in polar solvent without damage, completely wraps SWNT in film as well as in solution condition and therefore, it still critically precludes from showing up the original characteristics of SWNT material. However, after the stepwise dipping processes in deionized water and acid solution, the properties of SWNT film become close to the SWNT characteristics according to the surfactant elimination. Compared to as-deposited SWNT film, the optical transmittance, surface roughness and resistivity noticeably increase after surfactant elimination processes and besides, the acid solution treatment generates the partially functionalization (-OH or -COOH group introduction) of SWNTs. Because the functionalization of SWNT increases the work function as well as number of catalytic, those have highly positive influences on the performances of electrodes for organic devices. Actually, compared to as-deposited or deionized water treated SWNT film, the HNO₃ treated SWNT film shows higher performance as source/drain electrode in organic thin film transistor and catalytic cathode electrode in dye sensitized solar cell.