Tailoring Structure, Energy Levels and Spin Properties of Hybrid Perovskites with Help from Large-Scale Hybrid DFT

Hybrid perovskites, especially low-dimensional ones, are opening new avenues of energy band, light emission, and spin properties by simultaneously tuning the organic and inorganic components. First-principles approaches are particularly useful to fill in fundamental information on energy bands and their properties, which are otherwise only indirectly accessible in experiment. Using a large-scale spin-orbit coupled hybrid density functional approach in the FHI-aims code (able to handle periodic unit cells of many thousands of atoms), the talk addresses energy band alignment and their spin properties across a large space of experimentally synthesized low-dimensional perovskites, in which hydrogen bonding plays a key structure-shaping role. In X-ray diffraction, hydrogen positions can be difficult to refine precisely and a simple density functional theory based post-relaxation of hydrogen positions only is shown to greatly improve the precision of hydrogen positions. Band structure calculations then reveal how targeted hydrogen bonding patters in low-dimensional perovskites can maximize properties of interest, e.g., the spin splitting energies of lead iodide based compounds. Additionally, electronic doping and lead-free low-dimensional perovskites will also be discussed.
This talk would not be possible without the large developer community of the FHI-aims code, as well as close collaborations with numerous colleagues in the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center funded by the Office of Basic Energy Sciences, Office of Science within the U.S. Department of Energy and in NSF Award Number DMR-2323803.