Hybrid Metal Halides: Advancing Optoelectronic Materials

Will investigate the introduction of an additional large cation (A cation) in the halide perovskite structure which leads to the disruption of the 3D perovskite framework, giving rise to 2D structures where the A cation intercalates between discrete perovskite layers. This class of perovskite materials, known as Ruddlesden-Popper (RP) perovskites, possess distinctively different physical properties com- pared to the 3D perovskites as a result of quantum confinement effects originating from the di- mensional reduction of the crystal structure. The unique configuration of the orderly alternating inorganic and inorganic layers in RP perovskites gives rise to an electronic structure known as quantum wells. The quantum wells are formed by the isolated perovskite layers that are electron- ically insulated from one another by the physical barriers provided by the organic spacers. The Ruddlesden-Popper layered materials can form relatively efficient solar cells despite their layered structure. We will investigate the properites of these materials in detail to find the key property responsible for the high performance of the solar cells. We will grow thin films of several of the layered Ruddlesden-Popper compounds with mixed organic cations (butylam- monium (BA) and methylammonium (MA)) and carry out grazing incidence wide angle X-ray scattering (GIWAXS) at Stanford Synchrotron Research Laboratory.