Ameliorating the photovoltaic conversion efficiency of ZnO nanorod based dye-sensitized solar cells by strontium doping

Strontium doped ZnO nanorods with various concentrations were grown by a simple and low-cost reflux method. The structure and morphology of the prepared samples were studied by X-ray diffraction and scanning electron microscopy. The results demonstrate the hexagonal wurtzite structure and the presence of strontium atoms in the ZnO lattice. Transmission emission microscopy, diffuse reflectance, and photoluminescence studies were also performed to characterize the prepared samples. The optical measurements revealed the shrinkage in the band gap from 3.24 to 3.18 on 3:97 M Sr:ZnO doping. Dye-sensitized solar cells (DSSCs) were fabricated by using the undoped and Sr2+ doped ZnO based photoanodes. Electrochemical impedance spectroscopic studies revealed the charge transfer properties of the prepared DSSCs. An increased short-circuit current density of 1.93 mAcm(-2) and photovoltaic conversion efficiency of 1.02% were obtained with 3:97 M Sr: ZnO based DSSC, while undoped ZnO based DSSC exhibited a current density of 1.37 mAcm(-2) and efficiency of 0.80%. The morphological changes and the improved light scattering ability of the doped ZnO have resulted in the enhanced photovoltaic performance.