Development of stable current collectors for large area dye-sensitized solar cells

Abstract

The substrate sheet resistance effect in a large area dye-sensitized solar cell (DSC) device is still the main factor responsible for low energy conversion efficiencies. In this work, current collectors made of metal lines were applied by magnetron sputtering on a transparent conducting glass substrate. The introduction of these metal lines enabled a decrease in the sheet resistance from 7.26 Omega.square(-1) to 2.52 Omega.square(-1), by depositing an optimized 1.0 mu m tungsten thick layer on the top of 1.5 mu m thick molybdenum lines. These Mo/W lines withstanded long-term stability when in contact with iodide/triiodide redox couple. Large area dye-sensitized solar cells with 36 cm(2) of active area were assembled and the power conversion efficiency increased from 0.54% to 1.62% when ten metal lines were applied in both electrodes. As a final design, Mo/W lines were only applied onto the counter-electrode and protected with an indium-tin oxide layer; the resulting device showed a power conversion efficiency of 3.43%, compared with the reference efficiency of 2.38%.