Ordered mesoporous Zn-doped SnO2 synthesized by exotemplating for efficient dye-sensitized solar cells

Ordered mesoporous zinc-doped SnO2 (Zn-doped meso-SnO2) particles with a high surface area and a 2D hexagonal-type pore structure are synthesized by a double-replication procedure using SBA-15 silica and CMK-3 carbon as successive hard templates. The double-replication procedure provides large mesopores (diameter similar to 10 nm), which are essential in dye-sensitized solar cells (DSCs) for the facile diffusion of redox electrolytes. It is shown that Zn doping into an ordered mesoporous SnO2 framework induces a negative shift in the flat-band potential (V-FB) and also increases the isoelectric point. Consequently, DSCs employing Zn-doped meso-SnO2 photoanodes demonstrate longer electron lifetimes and increased dye loading than their undoped meso-SnO2 counterparts. A maximum energy-conversion efficiency (eta) of 3.73% is achieved from solar cells fabricated with 3 mol% Zn-doped meso-SnO2 photoanodes, a nearly five-fold improvement compared to undoped meso-SnO2 photoanode DSCs (eta = 0.81%).