The determination of the work function of conductive films plays a crucial role in the application of display devices. With the batch application of flexible displays based on new material technologies such as graphene, there is an increasing need for industrialization to accurately measure the work function of graphene flexible conductive films. So far, the mainstream work function testing method is the Kelvin Probe Force Microscopy (KPFM) method. This method is accurate and can obtain information such as material morphology within the test range at the same time. Therefore, it is widely used in the market to test the work function of indium tin oxide (ITO) glass in the previous generation of non-flexible display devices. The disadvantages of the KPFM method are that the test time is relatively long and the test range is small, usually tens to hundreds of square microns. Because the graphene film has a higher degree of defects, the distribution uniformity of the work function in the film is lower than that of ITO glass. At this time, the advantages of measuring work function using photoelectron spectroscopy (UPS method) gradually emerged. First of all, the maximum testing range of the UPS method can be up to 2 mm╳2 mm, which avoids the too microscopic characteristics of KPFM to a certain extent. Secondly, the UPS test is convenient and fast, and the test results can be obtained within a few minutes. In addition, the UPS method can also obtain the energy band information of the sample at the same time. Therefore, the UPS method dynamometer function can be a useful supplement to the KPFM method. The KPFM method is suitable for research and development and other occasions that require high microscopic precision. The UPS method can quickly and accurately obtain the overall work function of the macroscopic film, and is suitable for quality control in batch delivery of products. This document standardizes the UPS method dynamometer function method to standardize the basic operations of the UPS method dynamometer function, so that this method can play a better role in the industrialization process led by flexible display devices.
T/ZSA 39-2020 history
2020T/ZSA 39-2020 Characterization of Graphene - Work function - Ultraviolet photoelectron spectroscopy (UPS) method