Fabrication of a double layered photoanode consisting of SnO2 nanofibers and nanoparticles for efficient dye-sensitized solar cells

Abstract

Hierarchical one-dimensional SnO₂ nanofibers (NFs) consisting of nanoparticles (NPs) have been synthesized and employed as an efficient light scattering layer to fabricate double layered dye-sensitized solar cells (DSSCs). The photovoltaic performance (5.44%) of the DSSC based on the SnO₂ NPs (14.5 μm)/NFs (4.0 μm) double layered photoanode showed a 26.3% enhancement compared to that of a SnO₂ NPs photoanode (18.5μm, 4.30%). Intensity modulation photocurrent spectroscopy (IMPS), intensity-modulated voltage spectroscopy (IMVS) and open-circuit voltage decay (OCVD) spectroscopy were used to investigate the kinetic process of electron transport and recombination within SnO₂ NPs or NPs/NFs based DSSCs, revealing a faster electron transport rate and a lower recombination rate in the SnO₂ NPs/NFs photoanode. The UV-vis diffuse reflectance spectroscopy results showed that the SnO₂ NPs/NFs possess better light scattering ability which enhanced their photovoltaic performance compared to the SnO₂ NPs. Furthermore, an overall power conversion efficiency of 6.31% (with a J_sc of 16.78 mA cm⁻², V_oc of 711 mV and FF of 0.53) was achieved for the SnO₂ NPs/NFs double layered photoanode with an additional SnO₂ blocking layer, which suppressed electron recombination between the FTO glass and the electrolyte.