Effects of counter electrode geometry on the power conversion efficiency of large-area dye-sensitized solar cells

Abstract

In order to design electrode with reasonable geometry for large-area dye-sensitized solar cells (DSSCs), the effect of counter electrode geometry on the power conversion efficiency (PCE) of DSSCs has been investigated. The fill factor and shunt resistance decrease with the increase of active area, which results in a relatively low PCE in large-area DSSCs. If the F-doped SnO2 (FTO) substrate of counter electrode is replaced by metal substrate while keeping the electrode geometry unchanged, the drop in PCE will be smaller, which indicates that Ag grids can’t help inject electrons to counter electrode as effective as those help collect electrons in photoanode. The variation of the PCE of DSSCs with same length and different width suggests that the PCE can be improved greatly by reducing active area from the width rather than the length, which is proportional to the distance between positive and negative ohmic contact, and a reference value related to the series resistance (Rs) is proposed that the PCE of DSSCs are influenced by the deviation between theoretical Rs and Rs obtained by measurement.