Photoemission Spectroscopy Studies of Methylammonium Lead Iodide Perovskite Thin Films and Interfaces

Organometal halide perovskites have recently emerged as promising materials for fundamentally low- cost, high-performance optoelectronics. In this thesis, we utilize thermal co-evaporation of PbI2 and CH3NH3 I to fabricate thin films of CH3NH3PbI3 . We first investigate the effect of stoichiometry on some of its structural, optical and electronic properties. Then, we study the energy level alignment of CH3NH3PbI3 with 6 organic semiconductors, revealing good agreement between the data and the theory of vacuum level alignment. Finally, the interface formed between CH3NH3PbI3 and MoO3 is examined. The findings suggest migration of iodide species into the oxide layer, resulting in deterioration of its chemical and electronic properties. Insertion of an organic interlayer is shown to mitigate these undesirable effects. The results of this work could be of use in device engineering, where knowledge of such interfacial phenomena is of utmost importance in achieving optimized device structures.M.A.S