Inclusion of amphoteric zinc oxide (ZnO) thin films in energy conversion technologies such as photovoltaics and batteries requires advancement in nanometer-scale control over  the morphology and chemical composition of the near-surface region; intrinsic and extrinsic doping of the layers to improve conductivity; and rates of interfacial charge transfer to enhance charge injection or extraction.  The following extensive theoretical and experimental protocol is used to understand the role of interfacial defects on interfacial charge transfer all as a function of oxygen content in synthesis gas for sputtered ZnO samples: x-ray photoelectron spectroscopy to identify the presence of surface defects surface defects (hydroxyls, oxygen and zinc vacancies, zinc interstitials, and gallium dopants);  DFT calculations, photoluminescence, and ultraviolet photoemission spectroscopy to evaluate the energetics of mid-gap states; extended x-ray absorption fine structure (EXAFS) measurements to determine interatomic distances.  Connections are made with application-based electrochemical measurements and organic photovoltaic device performance.

Atomic-level defects in ZnO: Is characterization possible?

245th National Meeting (2013)

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