Effect of Blocking Layer to Boost Photoconversion Efficiency in ZnO Dye-Sensitized Solar Cells

Year: 2014

Authors: Selopal GS., Memarian N., Milan R., Concina I., Sberveglieri G., Vomiero A.

Autors Affiliation: Univ Brescia, Dept Informat Engn, SENSOR Lab, I-25133 Brescia, Italy; CNR INO SENSOR Lab, I-25123 Brescia, Italy; Semnan Univ, Fac Phys, Semnan, Iran.

Abstract: The effect of a ZnO compact blocking layer (BL) in dye-sensitized solar cells (DSSCs) based on ZnO photoanodes is investigated. BL is generated through spray deposition onto fluorine-doped tin oxide (FTO) conducting glass before the deposition of a ZnO active layer. The functional properties of dye-sensitized solar cells (DSSCs) are then investigated as a function of the thickness of the BL for two different kinds of ZnO active layer, i.e., hierarchically self-assembled nanoparticles and microcubes composed of closely packed ZnO sheets. Presence of BL leads to the improvement of photoconversion efficiency (PCE), by physically insulating the electrolyte and the FTO. This effect increases at increasing BL thickness up to around 800 nm, while thicker BL results in reduced cell performance. Remarkable increase in J(sc) is recorded, which doubles as compared to cells without blocking layer, leading to PCE as high as 5.6% in the best cell under one sun irradiation (AM 1.5 G, 100 mW cm(-2)). Electrochemical impedance spectroscopy (EIS) elucidates the mechanism boosting the functional features of the cells with BL, which relies with enhanced chemical capacitance together with an almost unchanged recombination resistance, which are reflected in an increased electron lifetime. The results foresee a straightforward way to significantly improve the performance of ZnO-based DSSCs.

Journal/Review: ACS APPLIED MATERIALS & INTERFACES

Volume: 6 (14)      Pages from: 11236  to: 11244

More Information: F-Light Marie Curie EC contract 299490, WIROX EC contract 295216, Regione Lombardia (National Research Council Project Tecnologie e Materiali per l’utilizzo efficiente dell’energia solare).
KeyWords: zinc oxide; dye sensitized solar cells; blocking layer; electron recombination
DOI: 10.1021/am501360a

Citations: 38
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