In reality, the linewidth is commonly of the order of 1.1 eV to 2 eV, depending on the state of samples (bulk, nanocrystal, or particles etc.), instrumental conditions and natural linewidth of O1s. Our calculations suggest that, under real experimental conditions, Vo 2+ and Vo 0 would be hardly visible by XPS. As the most stable native defect in ZnO, Vo is very important for physical properties. For decades, researchers have been correlating Vo with the defect peak situated between the lattice O 2-and surface -OH peak in XPS analysis. We show some of the literature results in Figure . As can be seen, Vo 2+ is usually claimed to have a Δ B.E. of 1.1eV-1.8eV, which is significantly larger than the simulated result. However, we hardly find any convincing evidence or explanation for such an assignment in the literature. In fact, the signal of Vo comes from the adjacent O atoms, which have complete four Zn neighbors and whose electronic structure is only slightly affected by Vo 2+ , as displayed below. Blue: more charge (0.08e/A 3 isosurface), Red: less charge ( -0.08e/A 3 isosurface). The atomic number is the same as in Figure .