KOH Treatment of Photoanode on Photovoltaic Properties of ZnO Based Dye-Sensitized Solar Cell

ZnO films were deposited on fluorine doped tin oxide glass substrate and chemically treated by KOH solutions. The films were immersed into 2 M KOH solution with various immersing time of 0-6 min at room temperature, rinsed and thermally treated. Small pore size was observed for treated films by scanning electron microscopy indicated that dense ZnO particles were removed. Eosin-Y sensitizer was loaded into treated photoanode using re-adsorption technique. The photovoltaic characteristics were investigated under standard light illumination (AM1.5). Short circuit current densities are not much changed for 0-4 min treatment. After then, it is rapidly decreased for 6 min treatment. Open-circuit voltage, fill factor and shunt resistance are increased after treatment. In addition, increased charge transfer resistance indicated that recombination is reduced by KOH solution treatment. The reduced recombination contributes efficient electrons transport through external circuit. These improvements resulting efficiency reached maximum value of 0.72% at 4 min treatment, compared with pristine cell efficiency of 0.64%.