Extended Data Fig. 2: XPS characterizations.
From: Multifunctional ytterbium oxide buffer for perovskite solar cells
a, Photograph of 1.5 nm YbOx film deposited on a large-scale ITO substrate (100 cm2) by a scalable thermal evaporation approach. The areas at the corner of the sample highlighted by the dotted box were used to conduct the XPS measurements. b, Yb 4d XPS spectra corresponding to the highlighted areas in (a). The XPS data show that YbOx on an 100-cm2 substrate can be formed when upscaling in the device fabrication chamber with a base pressure of 10−4 Pa.
