UPS analysis of (semi)conducting samples allows the measurement of the work function of a material. Combined with XPS, this is a powerful combination of techniques to gain information about the valence structure of the surface. Here, a thin film, hybrid organic-inorganic lead bromide perovskite is analysed using a Kratos AXIS spectrometer. A comparison of the data is made after the removal of adventitious carbon with the Gas Cluster Ion Source (GCIS) to interpret how the work function of the material is affected.