Hierarchical Tin Oxide Nanostructures for Dye‐Sensitized Solar Cell Application

Abstract

Nanoscale material manipulation is the key to increasing solar light harvesting and photon‐to‐electron conversion efficiency (PCE) for an organic–inorganic photovoltaic system. Many SnO2 1D nanostructures, including nanowires and nanobelts, have been employed because of their potential of enhancing the charge collection properties of DSSCs by eliminating losses caused by grain boundary scattering of carriers in nanoparticle‐based DSSCs. Here, a new approach to growing hierarchical 1D SnO2 nanostructured layer by catalyst‐assisted pulsed laser deposition after introducing NiO into the SnO2 target is reported, and a plausible growth mechanism to describe the observed hierarchical nanostructures is presented. A remarkable improvement in the solar cell performance, including open circuit voltage, short circuit current density, fill factor, and PCE, by simple surface modification of the hierarchical SnO2 nanostructured photoanode is further demonstrated. Surface passivation is achieved on the as‐deposited hierarchical SnO2 nanostructures by dip coating with an MgO passivation layer of appropriately optimized thickness. Such an insulating layer is found to effectively reduce the recombination process caused by the higher electron mobility of SnO2 photoanode nanostructures. Compared with a pristine SnO2 nanobelt photoanode, a tenfold enhancement in their PCE (to 4.14%) has been observed for MgO‐passivated hierarchical SnO2 nanostructures.