Afshan Jamshaid, Scanning Probe Microscopy Studies of Metal Halide Perovskite Materials
Speaker: Afshan Jamshaid, Energy Materials and Surface Sciences (Qi) Unit
Title: Scanning Probe Microscopy Studies of Metal Halide Perovskite Materials
Abstract: Presently, no atomic scale research has been done on organic-inorganic polycrystalline perovskite (photovoltaic) material (MAPbI3=CH3NH3PbI3) interfaced with TiO2, silicon (Si) or silver (Ag) substrates for photovoltaic applications. Also, the influence of dopants on the electronic and optical properties of perovskite is still under intensive debates. Dopants have been suggested to resolve the thermal instability and degradation problems of perovskite. Instabilities and degradation occur in perovskite materials due to their interaction with water, oxygen, etc. A fundamental understanding of the origin of the dopants interactions with perovskite materials would provide useful insight to the design of stable and high performance perovskite (PVSK) solar cells for production at the industrial scale. Perovskite thin films with dopants will be fabricated using molecular beam epitaxy (thermal evaporation) in Ultra High Vacuum chambers (UHV). Low-temperature Scanning Tunneling Microscopy (LT-STM) will be used for atomic scale 2D imaging. Also, Scanning Tunneling Spectroscopy (STS), X-Ray Photoelectron Spectroscopy (XPS), Ultraviolet Photoelectron Spectroscopy (UPS) and Inverse Photoemission spectroscopy (IPES) will be used for characterizing the PVSK electronic properties. To solve the instabilities and degradation problems in perovskite materials for stable solar cells, I propose an original approach that consists of revealing the underlying fundamental processes at the origin of the instabilities and degradation processes in PVSK at the atomic scale. In addition, I will provide the experimental understanding of how the electronic and optical properties of polycrystalline perovskite material can be affected by different dopants such as PbCl2, RbI, KI, NaI, CsI, and LiI. The influence of the interface will be analyzed by using different substrates (TiO2, Ag, Au, and Si) because these substrates have a different conductivity and may play a crucial role in instabilities of perovskite solar cells. This study will provide the insight on the unique perovskite material instabilities issues and that associated with degradation problems in solar cells.