Improving the photovoltaic conversion efficiency of ZnO based dye sensitized solar cells by indium doping

Abstract

Indium doped zinc oxide nanoparticles (NPs) with various indium concentrations were prepared by cost effective and low temperature aqueous solution method. The structure and chemical composition of the material were characterized using X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that indium doped ZnO maintained a hexagonal wurtzite structure, and that indium atoms were successfully incorporated into the lattice of ZnO. The doping of indium has a significant influence on the optical properties of ZnO. Indium doping into ZnO nanoparticle photoanodes could simultaneously capture and transport photogenerated electrons injected into ZnO by excited dyes. This approach was useful for electrons to fluently transfer to the collection electrode due to the decreased internal resistance and electron recombination loss. The dye sensitized solar cells (DSSCs) based on 0.2 mm indium doped ZnO photoanode exhibited a high short-circuit photocurrent density of 12.58 mA/cm2 and a power conversion efficiency (PCE) of 2.7% whereas DSSCs made from pure ZnO NPs exhibited a current density of 8.02 mA/cm2 with 1.8% efficiency. Both the improved surface area and the enhanced light scattering could increase the light-harvesting efficiency of the photoelectrode and, thus, promote the overall conversion efficiency of solar cells.