Synthesize of aluminum zinc oxide nanowires for dye sensitized solar cell application

Abstract

Zinc oxide nanowires (ZnO NWs) have evoked extensive attention in recent years because of their potential technological applications. Aluminum (Al-ZnO) doped ZnO NWs have been deposited onto indium tin oxide (ITO) glass substrate, by using sol-gel spin coating and hydrothermal methods. Al-ZnO NWs with the percentage of Al content up to 6% were annealed at 450–600 °C. The structural, electrical and optical properties of the samples were characterized with X-ray diffraction (XRD), Energy-dispersive X-ray (EDX) spectroscope, Field-emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), and UV-Visible spectrophotometer and photoluminescence (PL) spectrometer. Meanwhile, the Al-ZnO NWs conductivity level was determined by Van der Pauw method. XRD analysis confirmed a single phase spinel structure with the crystallite size between 20-50 nm calculated using the Scherrer’s formula. The highest main diffraction peak corresponding to the (002) orientation was due to the dominant phase of Al-ZnO at annealing temperature of 550 °C. The FE-SEM and AFM micrographs displayed the formation of well-defined and homogenous crystallite grains. The biggest grain size of 37 nm was observed for Al-ZnO NWs prepared with 6% Al concentration and annealed at 550 °C. The samples showed a high transmittance of more than 85% in the visible region, with energy band gap in the range of 3.25 to 3.35 eV. In addition, the electrical measurement result of the Al-ZnO NWs showed the lowest conductivity value of 2.49×10-4 S/cm with the activation energy Ea = 27 meV. A dye sensitized solar sell (DSSC) with this design showed a high short-circuit current density of 3.94 mA/cm2 and open circuit voltage of 0.48 V. A DSSC with efficiency of 0.72% was achieved using this photo-anode.