ZnO@SnO2 engineered composite photoanodes for dye sensitized solar cells
Authors: Milan R., Selopal G. S., Epifani M., Natile M. M., Sberveglieri G., Vomiero A., Concina I.
Autors Affiliation: 1,2,5,7 : Department of Information Engineering, University of Brescia, via Valotti 9, Brescia, Italy;
1,2,5,7 : CNR-INO SENSOR Laboratory, via Branze 45, Brescia, Italy;
3 : Istituto per la Microelettronica e Microsistemi, IMMCNR, via Monteroni, Lecce, Italy
4 : CNR-IENI, Department of Chemical Sciences, University of Padova, via F. Marzolo 1, Padova, Italy
6 : Department of Engineering Science and Mathematics, Luleå University of Technology, Luleå, Sweden
Abstract: Layered multi-oxide concept was applied for fabrication of photoanodes for dye-sensitized solar cells based on ZnO and SnO2, capitalizing on the beneficial properties of each oxide. The effect of different combinations of ZnO@SnO2 layers was investigated, aimed at exploiting the high carrier mobility provided by the ZnO and the higher stability under UV irradiation pledged by SnO2. Bioxide photoanodes performed much better in terms of photoconversion efficiency (PCE) (4.96%) compared to bare SnO2 (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 SnO2 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 SnO2) and low recombination resistance (guaranteed by ZnO) and inhibition of back electron transfer from the SnO2 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.
Journal/Review: SCIENTIFIC REPORTS
Volume: 5 Pages from: 14523 to: 14523
KeyWords: open-circuit voltage; electrical-properties; nanocrystalline SNO2