Study of UV‐Induced ITO Work Function Changes Using Photoemission Yield Spectroscopy

ABSTRACT Transparent conductive oxides (TCOs) are often used as electrodes or charge transport layers. Some of the most essential parameters of TCOs are their optical transmittance, electrical conductivity, and work function (WF). It has been shown that ultraviolet photoemission spectroscopy (UPS) measurements can induce WF shifts. In this work, the UV‐induced WF shift in indium tin oxide (ITO) samples was studied using photoemission yield spectroscopy (PYS) as an alternative to the more commonly used UPS. Despite the low intensity of UV radiation, the ITO work function (WF ITO ) shifts of around 0.6 eV from the initial 4.69 to 4.07 eV after 10 measurements were observed. These measurements were done in a vacuum. Ten minutes in air were enough for WF ITO to return to the initial value, hinting that the effect could be UV‐induced desorption of surface oxygen. Taking advantage of PYS, the series of measurements was performed in air. In that case, no WF shift was observed, indicating that PYS is an efficient method for WF studies without altering the sample surface.