Effect of Various Factors for the Electrochemical Adsorption of Polydopamine on TiO2 Film

To fabricate polydopamine-sensitized solar cells with improved solar power conversion efficiency, the effects of pH, buffer, adsorption time and electrode potential for the electrochemical oxidation and polymerization of dopamine on TiO2 film were investigated. The optimum pH was around 7. It was found that the use of a buffer, especially 2-(N-morpholino)ethanesulfonic acid, significantly deteriorated the electrochemical adsorption of polydopamine, and the highest solar power conversion efficiency was obtained without buffer. With increasing adsorption time, the amount of adsorbed polydopamine increased but the solar power conversion efficiency decreased, suggesting the increased resistivity of polydopamine with a larger degree of polymerization. It was suggested that the reversal of electrode potential from positive to negative would be essential for the electrochemical adsorption of polydopamine.