Enhancing the solar cell efficiency through pristine 1-dimentional SnO2 nanostructures: Comparison of charge transport and carrier lifetime of SnO2 particles vs. nanorods

Abstract

Efficiency of dye-sensitized solar cells (DSSC) fabricated with pristine SnO2 nanocrystals was reported to be less superior compared to DSSC based on mesoporous TiO2 nanoparticles though both oxides have comparable electrical and surface properties. Owing to inherent high charge recombination properties of SnO2 nanoparticles, photoanode fabricated with SnO2 nanoparticles resulting in unexpected low open circuit voltage (Voc) and fill factor (FF). To overcome inherent charge recombination in SnO2, we investigated pristine SnO2 nanorods and showed enhanced Voc, FF and overall conversion efficiency (η) for SnO2 nanorods. The photoanode made of SnO2 nanorods yields nearly a 2-fold improvement in fill factor, 5 fold increases in η and a greater than 2-fold increase in short-circuit current density with a moderate increase in open-circuit photovoltage. The effects appear to arise primarily from longer electron lifetimes and reduced charge recombination of SnO2 nanorod based solar cells compared to that of SnO2 particles owing to 1-D nature of SnO2 nanorod which were evaluated by open-circuit voltage decay (OCVD) and electrochemical impedance spectroscopy (EIS) methods.