10.1021/acs.jpcc.5b07728.s001 Haipeng Xie Haipeng Xie Xiaoliang Liu Xiaoliang Liu Lu Lyu Lu Lyu Dongmei Niu Dongmei Niu Qi Wang Qi Wang Jinsong Huang Jinsong Huang Yongli Gao Yongli Gao Effects of Precursor Ratios and Annealing on Electronic Structure and Surface Composition of CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> Perovskite Films American Chemical Society 2016 precursor ratio core level shift annealing MAPbI 3 film CH 3NH Perovskite FilmsThe CH 3NH XPS core level analysis UPS MAPbI 3 film shift binding energy 2016-01-14 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Effects_of_Precursor_Ratios_and_Annealing_on_Electronic_Structure_and_Surface_Composition_of_CH_sub_3_sub_NH_sub_3_sub_PbI_sub_3_sub_Perovskite_Films/2088097 The electronic structure and surface composition of CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> (MAPbI<sub>3</sub>) films fabricated by one-step method with different precursor ratios of PbI<sub>2</sub> to CH<sub>3</sub>NH<sub>3</sub>I (PbI<sub>2</sub>/MAI) have been investigated with ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). It is found that the core levels of all components in the MAPbI<sub>3</sub> film shift toward lower binding energy with decreasing the precursor ratio of PbI<sub>2</sub>/MAI, indicating that the electronic structures of the MAPbI<sub>3</sub> film can be adjusted by the precursor ratio of PbI<sub>2</sub>/MAI. The elemental compositions of the MAPbI<sub>3</sub> film also depend on the precursor ratio and annealing process, and the compositions are strongly correlated to the electronic properties of the films. The electronic properties remain unchanged with an annealing at 110 °C. However, a core level shift of 0.5 eV toward higher binding energy is observed with an annealing at 150 °C, together with noticeable composition change from the XPS core level analysis. The distribution of all chemical components in the MAPbI<sub>3</sub> film is further investigated with angle-resolved XPS (AR-XPS). It is observed that annealing at 150 °C leads to relatively shallow distribution variations of I and Pb in the MAPbI<sub>3</sub> film, accompanied by infiltration of metallic Pb into the bulk.