Work function of fluorine doped tin oxide

Abstract

Fluorine doped tin oxide (FTO) is a commonly used transparent conducting oxide in optoelectronic device applications. The work function of FTO is commonly cited as 4.4 eV, which is incommensurate with recent device performance results. Using x-ray photoelectron spectroscopy, the authors measured the work function of commercial FTO to be 5.0±0.1 eV. UV ozone treatment was found to increase the work function by ∼0.1 eV due to surface band bending. The origins of the much lower work function previously reported are also discussed and are found to be a result of carbon contamination and UV induced work function lowering.