Face Selective Etching of ZnO During Attachment of Dyes

TitleFace Selective Etching of ZnO During Attachment of Dyes
Publication TypeJournal Article
Year of Publication2013
AuthorsPalacios-Lidóna, E, Pickup, DF, Johnson, PS, Ruther, RE, Tena-Zaera, R, Hamers, RJ, Colchero, J, Himpsel, FJ, Ortega, JE, Rogero, C
JournalJournal of Physical Chemistry C
Date Published2013

Scanning force microscopy and near edge X-ray absorption spectroscopy are used to study the attachment of Protoporphyrin IX dye molecules to the low-index single crystal faces of ZnO, i.e., the polar (000-1) face and the non-polar (10-10) face. We show how surface etching depends on the crystal face for various dye immobilization procedures: while the polar (000-1) surface remains nearly unaltered, the non-polar (10-10) surface is strongly etched by acidic solutions. These results demonstrate selective attachment of dye molecules onto ZnO surfaces, showing that it is extremely sensitive to both the exposed facet as well as to the immobilization protocol. This could be a factor in the surprisingly poor efficiency observed for ZnO based dye-sensitized solar cells, especially those using ZnO nanorod arrays.

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