Optimization of a New ZnO Nanorods Hydrothermal Synthesis Method for Solid State Dye Sensitized Solar Cells Applications

We report on the growth control of zinc oxide nanorods to point out the effect of the ZnO nanorods quality on the power conversion efficiency (PCE) of transparent conductive oxide (TCO)/ZnO nanorods/dye/spiro-OMe-TAD/metal electrode photovoltaic devices. A promising PCE of 0.61% was measured for the best nanorods growth conditions. A careful control of all the growth parameters during the seeds layer deposition and the hydrothermal synthesis was necessary to reach such a high PCE for this kind of device. A regular nanorod layer with a flat upper surface was obtained for ethylenediamine to zinc acetate dihydrate molar ratio equal to 1.74 and a pH of 8.2. The growth was performed at 65 degrees C for 2 h to avoid zinc oxide brushes deposition on the surface, arising from zinc hydroxyacetate decomposition during the hydrothermal treatment. The effect of ZnO nanorods length (ranging from 1 to 3 mu m) on solar cell efficiency was tested. Although the UV-vis absorption increases when the nanorods length increases, the best photovoltaic parameters were measured for the shortest nanorods length studied (1 mu m).