A Rapid Synthesis of Vertically Aligned Taper-Like K-Doped ZnO Nanostructures to Enhance Dye-Sensitized Solar Cell Efficiency

Abstract

Large-scale K-doped ZnO nanotapers were successfully grown on an indium tin oxide (ITO) substrate using a facile electrochemical route. The structural and morphologic analysis exhibited that the K-doped ZnO nanostructures had a nanotaper morphology and strong preferential [0001] c-axis direction with a hexagonal polycrystalline structure. The optical results show that the incorporation of K+ ions as the donors in a ZnO lattice leads to substantial modulation of the band gap structure of ZnO nanotapers, which results in a redshift in the ultraviolet emission peaks. The considerable enhancement of performance in K-doped ZnO-based dye-sensitized solar cells (DSSCs) can be related to the doping structure, which leads to higher dye loading (3.34 × 10−8 mol/cm2). The good photovoltaic behavior of the K-doped ZnO nanotapers can be attributed to the higher surface-to-volume ratio and large K-doped ZnO nanotaper/ITO interfacial band bending, indicating the potential of a low-temperature aqueous electrochemical approach to synthesizing doped ZnO nanotapers for DSSCs.