 doping limits, band gaps, work functions and energy band alignments of undoped and donor-doped transparent conducting oxides ZN0 and 203 and SN02 as accessed by X-ray and ultraviolet photoelectron spectroscopy XPS slash UPS are summarized and compared. The presented collection provides an extensive data set of technologically relevant electronic properties of photovoltaic transparent electrode materials and illustrates how these relate to the underlying defect chemistry, the dependence of surface dipoles on crystallographic orientation and or surface termination and Fermi level pinning. This article was authored by Diana E. Prophet, Thomas O. Mason, Stephen P. Harvey and others.