Synthesis of hierarchical SnO2 octahedra with tailorable size and application in dye-sensitized solar cells with enhanced power conversion efficiency

Abstract

Following the previous report on the fabrication of three-dimensional hierarchical SnO₂ octahedra consisting of nanoparticles via a rapid sonochemical process (Wang et al., Chem.–Eur. J., 2010, 16, 8620–8625), the influences of ultrasonic time, amplitude, ratio of H₂O–diethylene glycol (DEG), and different Sn salts on the morphology and size of SnO₂ have been further investigated in the present article. The hierarchical SnO₂ octahedra with average edge lengths of 0.5, 0.8, 1.0, 1.5 and 1.8 μm composed of 30–40 nm SnO₂ nanoparticles have been successfully obtained. The power conversion efficiencies of dye-sensitized solar cells (DSSCs) based on the hierarchical SnO₂ octahedra photoanodes varied from 5.57%, 5.82%, 6.40%, 6.45% to 6.80% with the corresponding octahedron sizes of 0.5, 0.8, 1.0, 1.5 and 1.8 μm, respectively. Intensity-modulated photocurrent spectroscopy (IMPS), intensity-modulated voltage spectroscopy (IMVS) and UV-vis diffuse spectroscopy were used to investigate the influences of the SnO₂ octahedron size on the photovoltaic performances of DSSCs.