Synthesis conditions, light intensity and temperature effect on the performance of ZnO nanorods-based dye sensitized solar cells

We present in this work a careful study of the different parameters affecting vertically-aligned ZnO-nanorods (NRs) based dye sensitized solar cells (DSCs). We analyze the effect of synthesis conditions, light intensity, UV light and working temperature, and correlated them to the final photovoltaic properties of the DSC. Although similar studies can be found in the literature for DSCs based on TiO2, this work is, to our knowledge, the first detailed study carried out for DSC based on vertically-aligned ZnO nanorods. The ZnO NRs were grown between 1.6 and 5.2 mu m long. Electrodes made with 1.6 +/- 0.2 mu m thickness were used to analyze parameters such as synthesis conditions, light intensity (800 similar to 1500W m(-2)), UV light irradiation and temperature (25-75 degrees C). We have also carried out initial analysis of the solar cell lifetime under continuous light irradiation at 45 degrees C, and analyzed the ZnO electrode before and after testing. The best photovoltaic response was characterized by a power conversion efficiency of 1.02%, with J(sc) of 3.72 mA cm(-2), V-oc of 0.603 V and 45% FF (at 72 degrees C), for a ZnO NR electrode of 5.2 mu m thickness. Comparison of our power conversion efficiency values with published data is also presented, as well as a brief discussion on the possible reasons behind the low power conversion efficiency observed for these type of solar cells. (C) 2011 Elsevier B.V. All rights reserved.