A Novel Buffering Technique for Aqueous Processing of Zinc Oxide Nanostructures and Interfaces, and Corresponding Improvement of Electrodeposited ZnO-Cu2O Photovoltaics

• Published in: Advanced functional materials Vol. 21; no. 3; pp. 573 - 582
• Main Authors: Musselman, Kevin P., Marin, Andrew, Wisnet, Andreas, Scheu, Christina, MacManus-Driscoll, Judith L., Schmidt-Mende, Lukas
• Format: Journal Article
• Language: English
• Published: New York WILEY-VCH Verlag 08.02.2011; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: anodic alumina; Aqueous solutions; Bilayers; Buffers; COPPER OXIDE; Copper oxides; CUPROUS OXIDE; DEPOSITION; ELECTRODEPOSITION; Heterojunctions; impedance spectroscopy; Materials science; MICROSTRUCTURES; MICROWIRE; Nanostructure; Nanowires; OXIDES; photovoltaic; Photovoltaic cells; SOLAR CELLS; Solar simulation; SOLUTIONS; Stability; ZINC OXIDE
• ISSN: 1616-301X; 1616-3028; 1616-3028
• DOI: 10.1002/adfm.201001956

A novel buffering method is presented to improve the stability of zinc oxide processed in aqueous solutions. By buffering the aqueous solution with a suitable quantity of sacrificial zinc species, the dissolution of functional zinc oxide structures and the formation of unwanted impurities can be prevented. The method is demonstrated for ZnO films and nanowires processed in aqueous solutions used for the selective etching of mesoporous anodic alumina templates and the electrochemical deposition of Cu2O. In both cases, improved ZnO stability is observed with the buffering method. ZnO‐Cu2O heterojunction solar cells (bilayer and nanowire cells) synthesized using both traditional and buffered deposition methods are characterized by impedance spectroscopy and solar simulation measurements. Buffering the Cu2O deposition solution is found to reduce unwanted recombination at the heterojunction and improve the photovoltaic performance. A novel buffering technique is presented for treatment of functional ZnO films and nanostructures in aqueous solutions. Buffering the solutions with sacrificial zinc species is found to prevent dissolution of the ZnO and unwanted precipitate formation. Bilayer and nanowire Cu2O–ZnO solar cells electrodeposited from buffered solutions display a greater resistance to unwanted recombination at their heterointerface and enhanced performance.