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.