Influence of Sintering Behavior of ZnO Nanoparticles on J-V Characteristics of ZnO-Based Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) are one of the promising photovoltaic devices because of their lower manufacturing cost and higher energy conversion efficiency. Wide-gap, porous semiconducting metal oxides are generally used as electrode materials of DSSCs. Previously we utilized ZnO as DSSC electrodes and achieved a high conversion efficiency of 6.58% by improving the structure of ZnO films. However, open-circuit voltage (V-OC), one of the factors to determine the performance of DSSCs, was still at a lower level (approximate to 0.60 V) than that of common TiO2-based cells. We believe that the lower V-OC is due mainly to the occurrence of recombination. In this work, we tried to enhance V-OC by controlling the heating process of electrodes and suppressing the recombination for further development of ZnO-based DSSCs. As a result, we have achieved a higher V-OC of 0.725 V, confirming that the sintering behavior (grain growth and/or necking of grains) influenced largely the characteristics of DSSCs.