Unique Zn-doped SnO2 nano-echinus with excellent electron transport and light harvesting properties as photoanode materials for high performance dye-sensitized solar cell

A unique Zn-doped SnO2 nano-echinus, characterized by nanowire-covered mesoporous spheres, was successfully synthesized in a binary ethylenediamine (En)/water solvent system using a solvothermal route. Combination of hierarchically assembled and well-defined spheres, high surface area, and doped-Zn makes our new nanostructures an interesting candidate for photoanode application in dye-sensitized solar cells (DSSCs) with excellent transport and light harvesting properties. Zn doping into the SnO2 framework also induces a negative shift in the flat-band potential (V-FB) and increases the isoelectric point. Consequently, the dye-sensitized solar cell employing Zn-doped SnO2 nano-echinus photoanodes exhibit higher open-circuit photovoltages, larger short-circuit currents, longer electron lifetimes, and increased dye loading than their undoped SnO2 counterparts. The energy-conversion efficiency (eta) 4.15% is achieved with 4.95 at.% Zn-doped SnO2 photoanodes, a nearly three-fold improvement compared to undoped SnO2 photoanode DSSCs (1.13%). The Zn-doped SnO2 nano-echinus is thus believed to be a very promising material, which has good potential for application in DSSCs.