Synergistic effect of Fe and Ag co-doping on the persistent photoconductivity of vertical ZnO nanorods

Undoped, doped and co-doped vertically aligned ZnO nanorods (NRs) are synthesized using sonicated sol-gel immersion method. A significant variation in structural, morphological, optical and photoconductivity properties of ZnO NRs after incorporation of transition metal ions (Fe or/and Ag) is obtained. XRD analysis revealed that incorporation of Fe ameliorates while that of Ag deteriorates the c-axis growth of NRs. The diameter of the NRs is tuned from 236 nm to 103 nm. The Fe-doped ZnO NRs exhibit significantly thinner diameter, longer length, and highest aspect ratio. The doping and co-doping reduces the optical band gap of ZnO by 20 meV and 10 meV respectively. A reduction in near band edge emission whereas enhancement in defect-related-green-emission is obtained. Noticeable enhancement in the light harvesting efficiency and significant quenching of the persistent photoconductivity is obtained by co-doping.