Facile electropolymerized-PANI as counter electrode for low cost dye-sensitized solar cell

The in situ electropolymerized-polyaniline (PANI) film (thickness: 5–20 μm) on FTO (fluorine tin oxide) glass doped by various counterions SO42-, ClO4-, BF4-, Cl−, p-toluenesulfonate (TsO−), etc. was prepared with electropolymerized charge capacity of 50–600 mC cm−2. Different doping counterions have great impact on the morphology, electrochemical activity of electropolymerized-PANI film. The electropolymerized-PANI doped by SO42- anion (PANI-SO4) film with much porous morphology and pore size diameter of several micrometers possesses higher reduction current for reduction of I3- and a low charge-transfer resistance of 1.3 Ω cm2 in comparison with Pt as counter electrode (CE). Dye-sensitized solar cell with PANI-SO4 as CE was assembled, and the device under full sunlight illumination (100 mW cm−2, AM 1.5 G) shows 5.6% photovoltaic conversion efficiency, which is comparable to 6.0% of that with Pt CE under the same experimental condition.