Zinc oxide (ZnO) films consisting of vertically aligned nanorods were hydrothermally grown on a seed layer at 90 °C using two precursors (zinc acetate, zinc nitrate). The microstructures and growth kinetics of ZnO films from various processing conditions were investigated to correlate to photovoltaic (PV) properties. For this, dye-sensitized solar cells (DSSCs) were assembled. Vertically grown nanorods exhibited the (002) out-of-plane texture and its size, alignment, density, and growth rate could be controlled by both solution and seed layer conditions. In particular, the stepwise deposition implemented by changing precursor solution every 2 h exhibited a higher power conversion efficiency (~2.3% for 1.55-μm-thick ZnO film) than the continuous deposition. The zinc acetate seed layer cured as low as 100 C enabled the templated growth of ZnO nanorods with an efficiency of ~1.7% (for thickness of 1.4 μm). This will allow current low-temperature processing to be adopted for the fabrication of low-cost flexible PV devices.
Lee, Sunghee, Biplab Kumar Roy, Junghyun Cho
Jpn. J. Appl. Phys.