jp5b07728_si_001.pdf (232.55 kB)
Effects of Precursor Ratios and Annealing on Electronic Structure and Surface Composition of CH3NH3PbI3 Perovskite Films
journal contribution
posted on 2016-01-14, 00:00 authored by Haipeng Xie, Xiaoliang Liu, Lu Lyu, Dongmei Niu, Qi Wang, Jinsong Huang, Yongli GaoThe electronic structure and surface
composition of CH3NH3PbI3 (MAPbI3) films fabricated
by one-step method with different precursor ratios of PbI2 to CH3NH3I (PbI2/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 MAPbI3 film shift toward
lower binding energy with decreasing the precursor ratio of PbI2/MAI, indicating that the electronic structures of the MAPbI3 film can be adjusted by the precursor ratio of PbI2/MAI. The elemental compositions of the MAPbI3 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 MAPbI3 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 MAPbI3 film, accompanied
by infiltration of metallic Pb into the bulk.