ZnO@SnO(2) engineered composite photoanodes for dye sensitized solar cells

Layered multi-oxide concept was applied for fabrication of photoanodes for dye-sensitized solar cells based on ZnO and SnO(2), capitalizing on the beneficial properties of each oxide. The effect of different combinations of ZnO@SnO(2) layers was investigated, aimed at exploiting the high carrier mobility provided by the ZnO and the higher stability under UV irradiation pledged by SnO(2). Bi-oxide photoanodes performed much better in terms of photoconversion efficiency (PCE) (4.96%) compared to bare SnO(2) (1.20%) and ZnO (1.03%). Synergistic cooperation is effective for both open circuit voltage and photocurrent density: enhanced values were indeed recorded for the layered photoanode as compared with bare oxides (V(oc) enhanced from 0.39 V in case of bare SnO(2) to 0.60 V and J(sc) improved from 2.58 mA/cm(2) pertaining to single ZnO to 14.8 mA/cm(2)). Improved functional performances of the layered network were ascribable to the optimization of both high chemical capacitance (provided by the SnO(2)) and low recombination resistance (guaranteed by ZnO) and inhibition of back electron transfer from the SnO(2) conduction band to the oxidized species of the electrolyte. Compared with previously reported results, this study testifies how a simple electrode design is powerful in enhancing the functional performances of the final device.