Photosensitization of nanocrystalline TiO2 films by a polymer with two carboxylic groups, poly (3-thiophenemalonic acid)

Photovoltaic devices were assembled using a conducting polymer; poly (3-thiophenemalonic acid) sensitized TiO2 electrodes and an electrolyte containing I3−/I− redox couple. This cell exhibited a short-circuit photocurrent ( J sc ) of ∼6.65 mA cm−2, an open circuit voltage ( V oc ) of ∼355 mV and an efficiency of 1.5% under the illumination of 100 mW cm−2 (AM 1.5). Addition of an ionic liquid, 1-methyl 3-n-hexylimidazolium iodide, into the electrolyte led to an improvement in the cell performances, achieving an overall efficiency of 1.8% under the same illumination. The average cell characteristics of the later devices are J sc = ∼ 7.6 mA cm - 2 , V oc = 365 mV with a fill factor of 0.65.